tracing: Use strlcpy() instead of strcpy() in __trace_find_cmdline()

Strcpy is inherently not safe, and strlcpy() should be used instead.
__trace_find_cmdline() uses strcpy() because the comms saved must have a
terminating nul character, but it doesn't hurt to add the extra protection
of using strlcpy() instead of strcpy().

Link: http://lkml.kernel.org/r/1493806274-13936-1-git-send-email-amit.pundir@linaro.org
Signed-off-by: Amey Telawane <ameyt@codeaurora.org>
[AmitP: Cherry-picked this commit from CodeAurora kernel/msm-3.10
https://source.codeaurora.org/quic/la/kernel/msm-3.10/commit/?id=2161ae9a70b12cf18ac8e5952a20161ffbccb477]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
[ Updated change log and removed the "- 1" from len parameter ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Merge tag 'trace-v4.12' of git://git./linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "New features for this release:

   - Pretty much a full rewrite of the processing of function plugins.
     i.e. echo do_IRQ:stacktrace > set_ftrace_filter

   - The rewrite was needed to add plugins to be unique to tracing
     instances. i.e. mkdir instance/foo; cd instances/foo; echo
     do_IRQ:stacktrace > set_ftrace_filter The old way was written very
     hacky. This removes a lot of those hacks.

   - New "function-fork" tracing option. When set, pids in the
     set_ftrace_pid will have their children added when the processes
     with their pids listed in the set_ftrace_pid file forks.

   - Exposure of "maxactive" for kretprobe in kprobe_events

   - Allow for builtin init functions to be traced by the function
     tracer (via the kernel command line). Module init function tracing
     will come in the next release.

   - Added more selftests, and have selftests also test in an instance"

* tag 'trace-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (60 commits)
  ring-buffer: Return reader page back into existing ring buffer
  selftests: ftrace: Allow some event trigger tests to run in an instance
  selftests: ftrace: Have some basic tests run in a tracing instance too
  selftests: ftrace: Have event tests also run in an tracing instance
  selftests: ftrace: Make func_event_triggers and func_traceonoff_triggers tests do instances
  selftests: ftrace: Allow some tests to be run in a tracing instance
  tracing/ftrace: Allow for instances to trigger their own stacktrace probes
  tracing/ftrace: Allow for the traceonoff probe be unique to instances
  tracing/ftrace: Enable snapshot function trigger to work with instances
  tracing/ftrace: Allow instances to have their own function probes
  tracing/ftrace: Add a better way to pass data via the probe functions
  ftrace: Dynamically create the probe ftrace_ops for the trace_array
  tracing: Pass the trace_array into ftrace_probe_ops functions
  tracing: Have the trace_array hold the list of registered func probes
  ftrace: If the hash for a probe fails to update then free what was initialized
  ftrace: Have the function probes call their own function
  ftrace: Have each function probe use its own ftrace_ops
  ftrace: Have unregister_ftrace_function_probe_func() return a value
  ftrace: Add helper function ftrace_hash_move_and_update_ops()
  ftrace: Remove data field from ftrace_func_probe structure
  ...

Merge branch 'for-linus' of git://git./linux/kernel/git/pmladek/printk

Pull printk updates from Petr Mladek:

 - There is a situation when early console is not deregistered because
   the preferred one matches a wrong entry. It caused messages to appear
   twice.

   This is the 2nd attempt to fix it. The first one was wrong, see the
   commit c6c7d83b9c9e ('Revert "console: don't prefer first registered
   if DT specifies stdout-path"').

   The fix is coupled with some small code clean up. Well, the console
   registration code would deserve a big one. We need to think about it.

 - Do not lose information about the preemtive context when the console
   semaphore is re-taken.

 - Do not block CPU hotplug when someone else is already pushing
   messages to the console.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: fix double printing with earlycon
  printk: rename selected_console -> preferred_console
  printk: fix name/type/scope of preferred_console var
  printk: Correctly handle preemption in console_unlock()
  printk: use console_trylock() in console_cpu_notify()

Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:

 - a few misc things

 - most of MM

 - KASAN updates

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (102 commits)
  kasan: separate report parts by empty lines
  kasan: improve double-free report format
  kasan: print page description after stacks
  kasan: improve slab object description
  kasan: change report header
  kasan: simplify address description logic
  kasan: change allocation and freeing stack traces headers
  kasan: unify report headers
  kasan: introduce helper functions for determining bug type
  mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page
  mm: hwpoison: call shake_page() unconditionally
  mm/swapfile.c: fix swap space leak in error path of swap_free_entries()
  mm/gup.c: fix access_ok() argument type
  mm/truncate: avoid pointless cleancache_invalidate_inode() calls.
  mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty
  fs/block_dev: always invalidate cleancache in invalidate_bdev()
  fs: fix data invalidation in the cleancache during direct IO
  zram: reduce load operation in page_same_filled
  zram: use zram_free_page instead of open-coded
  zram: introduce zram data accessor
  ...

kasan: separate report parts by empty lines

Makes the report easier to read.

Link: http://lkml.kernel.org/r/20170302134851.101218-10-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: improve double-free report format

Changes double-free report header from

  BUG: Double free or freeing an invalid pointer
  Unexpected shadow byte: 0xFB

to

  BUG: KASAN: double-free or invalid-free in kmalloc_oob_left+0xe5/0xef

This makes a bug uniquely identifiable by the first report line.  To
account for removing of the unexpected shadow value, print shadow bytes
at the end of the report as in reports for other kinds of bugs.

Link: http://lkml.kernel.org/r/20170302134851.101218-9-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: print page description after stacks

Moves page description after the stacks since it's less important.

Link: http://lkml.kernel.org/r/20170302134851.101218-8-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: improve slab object description

Changes slab object description from:

  Object at ffff880068388540, in cache kmalloc-128 size: 128

to:

  The buggy address belongs to the object at ffff880068388540
   which belongs to the cache kmalloc-128 of size 128
  The buggy address is located 123 bytes inside of
   128-byte region [ffff880068388540, ffff8800683885c0)

Makes it more explanatory and adds information about relative offset of
the accessed address to the start of the object.

Link: http://lkml.kernel.org/r/20170302134851.101218-7-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: change report header

Change report header format from:

  BUG: KASAN: use-after-free in unwind_get_return_address+0x28a/0x2c0 at addr ffff880069437950
  Read of size 8 by task insmod/3925

to:

  BUG: KASAN: use-after-free in unwind_get_return_address+0x28a/0x2c0
  Read of size 8 at addr ffff880069437950 by task insmod/3925

The exact access address is not usually important, so move it to the
second line.  This also makes the header look visually balanced.

Link: http://lkml.kernel.org/r/20170302134851.101218-6-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: simplify address description logic

Simplify logic for describing a memory address.  Add addr_to_page()
helper function.

Makes the code easier to follow.

Link: http://lkml.kernel.org/r/20170302134851.101218-5-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: change allocation and freeing stack traces headers

Change stack traces headers from:

  Allocated:
  PID = 42

to:

  Allocated by task 42:

Makes the report one line shorter and look better.

Link: http://lkml.kernel.org/r/20170302134851.101218-4-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: unify report headers

Unify KASAN report header format for different kinds of bad memory
accesses.  Makes the code simpler.

Link: http://lkml.kernel.org/r/20170302134851.101218-3-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kasan: introduce helper functions for determining bug type

Patch series "kasan: improve error reports", v2.

This patchset improves KASAN reports by making them easier to read and a
little more detailed.  Also improves mm/kasan/report.c readability.

Effectively changes a use-after-free report to:

  ==================================================================
  BUG: KASAN: use-after-free in kmalloc_uaf+0xaa/0xb6 [test_kasan]
  Write of size 1 at addr ffff88006aa59da8 by task insmod/3951

  CPU: 1 PID: 3951 Comm: insmod Tainted: G    B           4.10.0+ #84
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
   dump_stack+0x292/0x398
   print_address_description+0x73/0x280
   kasan_report.part.2+0x207/0x2f0
   __asan_report_store1_noabort+0x2c/0x30
   kmalloc_uaf+0xaa/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc2
  RIP: 0033:0x7f22cfd0b9da
  RSP: 002b:00007ffe69118a78 EFLAGS: 00000206 ORIG_RAX: 00000000000000af
  RAX: ffffffffffffffda RBX: 0000555671242090 RCX: 00007f22cfd0b9da
  RDX: 00007f22cffcaf88 RSI: 000000000004df7e RDI: 00007f22d0399000
  RBP: 00007f22cffcaf88 R08: 0000000000000003 R09: 0000000000000000
  R10: 00007f22cfd07d0a R11: 0000000000000206 R12: 0000555671243190
  R13: 000000000001fe81 R14: 0000000000000000 R15: 0000000000000004

  Allocated by task 3951:
   save_stack_trace+0x16/0x20
   save_stack+0x43/0xd0
   kasan_kmalloc+0xad/0xe0
   kmem_cache_alloc_trace+0x82/0x270
   kmalloc_uaf+0x56/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc2

  Freed by task 3951:
   save_stack_trace+0x16/0x20
   save_stack+0x43/0xd0
   kasan_slab_free+0x72/0xc0
   kfree+0xe8/0x2b0
   kmalloc_uaf+0x85/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc

  The buggy address belongs to the object at ffff88006aa59da0
   which belongs to the cache kmalloc-16 of size 16
  The buggy address is located 8 bytes inside of
   16-byte region [ffff88006aa59da0, ffff88006aa59db0)
  The buggy address belongs to the page:
  page:ffffea0001aa9640 count:1 mapcount:0 mapping:          (null) index:0x0
  flags: 0x100000000000100(slab)
  raw: 0100000000000100 0000000000000000 0000000000000000 0000000180800080
  raw: ffffea0001abe380 0000000700000007 ffff88006c401b40 0000000000000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   ffff88006aa59c80: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc
   ffff88006aa59d00: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc
  >ffff88006aa59d80: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
                                    ^
   ffff88006aa59e00: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
   ffff88006aa59e80: fb fb fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc
  ==================================================================

from:

  ==================================================================
  BUG: KASAN: use-after-free in kmalloc_uaf+0xaa/0xb6 [test_kasan] at addr ffff88006c4dcb28
  Write of size 1 by task insmod/3984
  CPU: 1 PID: 3984 Comm: insmod Tainted: G    B           4.10.0+ #83
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
   dump_stack+0x292/0x398
   kasan_object_err+0x1c/0x70
   kasan_report.part.1+0x20e/0x4e0
   __asan_report_store1_noabort+0x2c/0x30
   kmalloc_uaf+0xaa/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc2
  RIP: 0033:0x7feca0f779da
  RSP: 002b:00007ffdfeae5218 EFLAGS: 00000206 ORIG_RAX: 00000000000000af
  RAX: ffffffffffffffda RBX: 000055a064c13090 RCX: 00007feca0f779da
  RDX: 00007feca1236f88 RSI: 000000000004df7e RDI: 00007feca1605000
  RBP: 00007feca1236f88 R08: 0000000000000003 R09: 0000000000000000
  R10: 00007feca0f73d0a R11: 0000000000000206 R12: 000055a064c14190
  R13: 000000000001fe81 R14: 0000000000000000 R15: 0000000000000004
  Object at ffff88006c4dcb20, in cache kmalloc-16 size: 16
  Allocated:
  PID = 3984
   save_stack_trace+0x16/0x20
   save_stack+0x43/0xd0
   kasan_kmalloc+0xad/0xe0
   kmem_cache_alloc_trace+0x82/0x270
   kmalloc_uaf+0x56/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc2
  Freed:
  PID = 3984
   save_stack_trace+0x16/0x20
   save_stack+0x43/0xd0
   kasan_slab_free+0x73/0xc0
   kfree+0xe8/0x2b0
   kmalloc_uaf+0x85/0xb6 [test_kasan]
   kmalloc_tests_init+0x4f/0xa48 [test_kasan]
   do_one_initcall+0xf3/0x390
   do_init_module+0x215/0x5d0
   load_module+0x54de/0x82b0
   SYSC_init_module+0x3be/0x430
   SyS_init_module+0x9/0x10
   entry_SYSCALL_64_fastpath+0x1f/0xc2
  Memory state around the buggy address:
   ffff88006c4dca00: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
   ffff88006c4dca80: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
  >ffff88006c4dcb00: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
                                    ^
   ffff88006c4dcb80: fb fb fc fc 00 00 fc fc fb fb fc fc fb fb fc fc
   ffff88006c4dcc00: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
  ==================================================================

This patch (of 9):

Introduce get_shadow_bug_type() function, which determines bug type
based on the shadow value for a particular kernel address.  Introduce
get_wild_bug_type() function, which determines bug type for addresses
which don't have a corresponding shadow value.

Link: http://lkml.kernel.org/r/20170302134851.101218-2-andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page

Memory error handler calls try_to_unmap() for error pages in various
states.  If the error page is a mlocked page, error handling could fail
with "still referenced by 1 users" message.  This is because the page is
linked to and stays in lru cache after the following call chain.

  try_to_unmap_one
    page_remove_rmap
      clear_page_mlock
        putback_lru_page
          lru_cache_add

memory_failure() calls shake_page() to hanlde the similar issue, but
current code doesn't cover because shake_page() is called only before
try_to_unmap().  So this patches adds shake_page().

Fixes: 23a003bfd23ea9ea0b7756b920e51f64b284b468 ("mm/madvise: pass return code of memory_failure() to userspace")
Link: http://lkml.kernel.org/r/20170417055948.GM31394@yexl-desktop
Link: http://lkml.kernel.org/r/1493197841-23986-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Xiaolong Ye <xiaolong.ye@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: hwpoison: call shake_page() unconditionally

shake_page() is called before going into core error handling code in
order to ensure that the error page is flushed from lru_cache lists
where pages stay during transferring among LRU lists.

But currently it's not fully functional because when the page is linked
to lru_cache by calling activate_page(), its PageLRU flag is set and
shake_page() is skipped.  The result is to fail error handling with
"still referenced by 1 users" message.

When the page is linked to lru_cache by isolate_lru_page(), its PageLRU
is clear, so that's fine.

This patch makes shake_page() unconditionally called to avoild the
failure.

Fixes: 23a003bfd23ea9ea0b7756b920e51f64b284b468 ("mm/madvise: pass return code of memory_failure() to userspace")
Link: http://lkml.kernel.org/r/20170417055948.GM31394@yexl-desktop
Link: http://lkml.kernel.org/r/1493197841-23986-2-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Xiaolong Ye <xiaolong.ye@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c: fix swap space leak in error path of swap_free_entries()

In swapcache_free_entries(), if swap_info_get_cont() returns NULL,
something wrong occurs for the swap entry.  But we should still continue
to free the following swap entries in the array instead of skip them to
avoid swap space leak.  This is just problem in error path, where system
may be in an inconsistent state, but it is still good to fix it.

Link: http://lkml.kernel.org/r/20170421124739.24534-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/gup.c: fix access_ok() argument type

MIPS just got changed to only accept a pointer argument for access_ok(),
causing one warning in drivers/scsi/pmcraid.c.  I tried changing x86 the
same way and found the same warning in __get_user_pages_fast() and
nowhere else in the kernel during randconfig testing:

  mm/gup.c: In function '__get_user_pages_fast':
  mm/gup.c:1578:6: error: passing argument 1 of '__chk_range_not_ok' makes pointer from integer without a cast [-Werror=int-conversion]

It would probably be a good idea to enforce type-safety in general, so
let's change this file to not cause a warning if we do that.

I don't know why the warning did not appear on MIPS.

Fixes: 2667f50e8b81 ("mm: introduce a general RCU get_user_pages_fast()")
Link: http://lkml.kernel.org/r/20170421162659.3314521-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/truncate: avoid pointless cleancache_invalidate_inode() calls.

cleancache_invalidate_inode() called truncate_inode_pages_range() and
invalidate_inode_pages2_range() twice - on entry and on exit.  It's
stupid and waste of time.  It's enough to call it once at exit.

Link: http://lkml.kernel.org/r/20170424164135.22350-5-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty

If mapping is empty (both ->nrpages and ->nrexceptional is zero) we can
avoid pointless lookups in empty radix tree and bail out immediately
after cleancache invalidation.

Link: http://lkml.kernel.org/r/20170424164135.22350-4-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/block_dev: always invalidate cleancache in invalidate_bdev()

invalidate_bdev() calls cleancache_invalidate_inode() iff ->nrpages != 0
which doen't make any sense.

Make sure that invalidate_bdev() always calls cleancache_invalidate_inode()
regardless of mapping->nrpages value.

Fixes: c515e1fd361c ("mm/fs: add hooks to support cleancache")
Link: http://lkml.kernel.org/r/20170424164135.22350-3-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: fix data invalidation in the cleancache during direct IO

Patch series "Properly invalidate data in the cleancache", v2.

We've noticed that after direct IO write, buffered read sometimes gets
stale data which is coming from the cleancache.  The reason for this is
that some direct write hooks call call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero, so we may not invalidate
data in the cleancache.

Another odd thing is that we check only for ->nrpages and don't check
for ->nrexceptional, but invalidate_inode_pages2[_range] also
invalidates exceptional entries as well.  So we invalidate exceptional
entries only if ->nrpages != 0? This doesn't feel right.

 - Patch 1 fixes direct IO writes by removing ->nrpages check.
 - Patch 2 fixes similar case in invalidate_bdev().
     Note: I only fixed conditional cleancache_invalidate_inode() here.
       Do we also need to add ->nrexceptional check in into invalidate_bdev()?

 - Patches 3-4: some optimizations.

This patch (of 4):

Some direct IO write fs hooks call invalidate_inode_pages2[_range]()
conditionally iff mapping->nrpages is not zero.  This can't be right,
because invalidate_inode_pages2[_range]() also invalidate data in the
cleancache via cleancache_invalidate_inode() call.  So if page cache is
empty but there is some data in the cleancache, buffered read after
direct IO write would get stale data from the cleancache.

Also it doesn't feel right to check only for ->nrpages because
invalidate_inode_pages2[_range] invalidates exceptional entries as well.

Fix this by calling invalidate_inode_pages2[_range]() regardless of
nrpages state.

Note: nfs,cifs,9p doesn't need similar fix because the never call
cleancache_get_page() (nor directly, nor via mpage_readpage[s]()), so
they are not affected by this bug.

Fixes: c515e1fd361c ("mm/fs: add hooks to support cleancache")
Link: http://lkml.kernel.org/r/20170424164135.22350-2-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Kuznetsov <kuznet@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nikolay Borisov <n.borisov.lkml@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: reduce load operation in page_same_filled

In page_same_filled function, all elements in the page is compared with
next index value.  The current comparison routine compares the (i)th and
(i+1)th values of the page.

In this case, two load operaions occur for each comparison.  But if we
store first value of the page stores at 'val' variable and using it to
compare with others, the load opearation is reduced.  It reduce load
operation per page by up to 64times.

Link: http://lkml.kernel.org/r/1488428104-7257-1-git-send-email-sangwoo2.park@lge.com
Signed-off-by: Sangwoo Park <sangwoo2.park@lge.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: use zram_free_page instead of open-coded

The zram_free_page already handles NULL handle case and same page so use
it to reduce error probability.  (Acutaully, I made a mistake when I
handled same page feature)

Link: http://lkml.kernel.org/r/1492052365-16169-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: introduce zram data accessor

With element, sometime I got confused handle and element access.  It
might be my bad but I think it's time to introduce accessor to prevent
future idiot like me.  This patch is just clean-up patch so it shouldn't
change any behavior.

Link: http://lkml.kernel.org/r/1492052365-16169-6-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: remove zram_meta structure

It's redundant now.  Instead, remove it and use zram structure directly.

Link: http://lkml.kernel.org/r/1492052365-16169-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: use zram_slot_lock instead of raw bit_spin_lock op

With this clean-up phase, I want to use zram's wrapper function to lock
table access which is more consistent with other zram's functions.

Link: http://lkml.kernel.org/r/1492052365-16169-4-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: partial IO refactoring

For architecture(PAGE_SIZE > 4K), zram have supported partial IO.
However, the mixed code for handling normal/partial IO is too mess,
error-prone to modify IO handler functions with upcoming feature so this
patch aims for cleaning up zram's IO handling functions.

Link: http://lkml.kernel.org/r/1492052365-16169-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram: handle multiple pages attached bio's bvec

Patch series "zram clean up", v2.

This patchset aims to clean up zram .

[1] clean up multiple pages's bvec handling.
[2] clean up partial IO handling
[3-6] clean up zram via using accessor and removing pointless structure.

With [2-6] applied, we can get a few hundred bytes as well as huge
readibility enhance.

x86: 708 byte save

    add/remove: 1/1 grow/shrink: 0/11 up/down: 478/-1186 (-708)
    function                                     old     new   delta
    zram_special_page_read                         -     478    +478
    zram_reset_device                            317     314      -3
    mem_used_max_store                           131     128      -3
    compact_store                                 96      93      -3
    mm_stat_show                                 203     197      -6
    zram_add                                     719     712      -7
    zram_slot_free_notify                        229     214     -15
    zram_make_request                            819     803     -16
    zram_meta_free                               128     111     -17
    zram_free_page                               180     151     -29
    disksize_store                               432     361     -71
    zram_decompress_page.isra                    504       -    -504
    zram_bvec_rw                                2592    2080    -512
    Total: Before=25350773, After=25350065, chg -0.00%

ppc64: 231 byte save

    add/remove: 2/0 grow/shrink: 1/9 up/down: 681/-912 (-231)
    function                                     old     new   delta
    zram_special_page_read                         -     480    +480
    zram_slot_lock                                 -     200    +200
    vermagic                                      39      40      +1
    mm_stat_show                                 256     248      -8
    zram_meta_free                               200     184     -16
    zram_add                                     944     912     -32
    zram_free_page                               348     308     -40
    disksize_store                               572     492     -80
    zram_decompress_page                         664     564    -100
    zram_slot_free_notify                        292     160    -132
    zram_make_request                           1132    1000    -132
    zram_bvec_rw                                2768    2396    -372
    Total: Before=17565825, After=17565594, chg -0.00%

This patch (of 6):

Johannes Thumshirn reported system goes the panic when using NVMe over
Fabrics loopback target with zram.

The reason is zram expects each bvec in bio contains a single page
but nvme can attach a huge bulk of pages attached to the bio's bvec
so that zram's index arithmetic could be wrong so that out-of-bound
access makes system panic.

[1] in mainline solved solved the problem by limiting max_sectors with
SECTORS_PER_PAGE but it makes zram slow because bio should split with
each pages so this patch makes zram aware of multiple pages in a bvec
so it could solve without any regression(ie, bio split).

[1] 0bc315381fe9, zram: set physical queue limits to avoid array out of
    bounds accesses

Link: http://lkml.kernel.org/r/20170413134057.GA27499@bbox
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Johannes Thumshirn <jthumshirn@suse.de>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, page_alloc: remove debug_guardpage_minorder() test in warn_alloc()

Commit c0a32fc5a2e4 ("mm: more intensive memory corruption debugging")
changed to check debug_guardpage_minorder() > 0 when reporting
allocation failures.  The reasoning was

  When we use guard page to debug memory corruption, it shrinks
  available pages to 1/2, 1/4, 1/8 and so on, depending on parameter
  value. In such case memory allocation failures can be common and
  printing errors can flood dmesg. If somebody debug corruption,
  allocation failures are not the things he/she is interested about.

but this is misguided.

Allocation requests with __GFP_NOWARN flag by definition do not cause
flooding of allocation failure messages.  Allocation requests with
__GFP_NORETRY flag likely also have __GFP_NOWARN flag.  Costly
allocation requests likely also have __GFP_NOWARN flag.

Allocation requests without __GFP_DIRECT_RECLAIM flag likely also have
__GFP_NOWARN flag or __GFP_HIGH flag.  Non-costly allocation requests
with __GFP_DIRECT_RECLAIM flag basically retry forever due to the "too
small to fail" memory-allocation rule.

Therefore, as a whole, shrinking available pages by
debug_guardpage_minorder= kernel boot parameter might cause flooding of
OOM killer messages but unlikely causes flooding of allocation failure
messages.  Let's remove debug_guardpage_minorder() > 0 check which would
likely be pointless.

Link: http://lkml.kernel.org/r/1491910035-4231-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c: add page flag description in error paths

It helps to provide page flag description along with the raw value in
error paths during soft offline process.  From sample experiments

Before the patch:

  soft offline: 0x6100: migration failed 1, type 3ffff800008018
  soft offline: 0x7400: migration failed 1, type 3ffff800008018

After the patch:

  soft offline: 0x5900: migration failed 1, type 3ffff800008018 (uptodate|dirty|head)
  soft offline: 0x6c00: migration failed 1, type 3ffff800008018 (uptodate|dirty|head)

Link: http://lkml.kernel.org/r/20170409023829.10788-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/madvise: move up the behavior parameter validation

madvise_behavior_valid() should be called before acting upon the
behavior parameter.  Hence move up the function.  This also includes
MADV_SOFT_OFFLINE and MADV_HWPOISON options as valid behavior parameter
for the system call madvise().

Link: http://lkml.kernel.org/r/20170418052844.24891-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/madvise.c: clean up MADV_SOFT_OFFLINE and MADV_HWPOISON

This cleans up handling MADV_SOFT_OFFLINE and MADV_HWPOISON called
through madvise() system call.

* madvise_memory_failure() was misleading to accommodate handling of
  both memory_failure() as well as soft_offline_page() functions.
  Basically it handles memory error injection from user space which
  can go either way as memory failure or soft offline. Renamed as
  madvise_inject_error() instead.

* Renamed struct page pointer 'p' to 'page'.

* pr_info() was essentially printing PFN value but it said 'page'
  which was misleading. Made the process virtual address explicit.

Before the patch:

Soft offlining page 0x15e3e at 0x3fff8c230000
Soft offlining page 0x1f3 at 0x3fffa0da0000
Soft offlining page 0x744 at 0x3fff7d200000
Soft offlining page 0x1634d at 0x3fff95e20000
Soft offlining page 0x16349 at 0x3fff95e30000
Soft offlining page 0x1d6 at 0x3fff9e8b0000
Soft offlining page 0x5f3 at 0x3fff91bd0000

Injecting memory failure for page 0x15c8b at 0x3fff83280000
Injecting memory failure for page 0x16190 at 0x3fff83290000
Injecting memory failure for page 0x740 at 0x3fff9a2e0000
Injecting memory failure for page 0x741 at 0x3fff9a2f0000

After the patch:

Soft offlining pfn 0x1484e at process virtual address 0x3fff883c0000
Soft offlining pfn 0x1484f at process virtual address 0x3fff883d0000
Soft offlining pfn 0x14850 at process virtual address 0x3fff883e0000
Soft offlining pfn 0x14851 at process virtual address 0x3fff883f0000
Soft offlining pfn 0x14852 at process virtual address 0x3fff88400000
Soft offlining pfn 0x14853 at process virtual address 0x3fff88410000
Soft offlining pfn 0x14854 at process virtual address 0x3fff88420000
Soft offlining pfn 0x1521c at process virtual address 0x3fff6bc70000

Injecting memory failure for pfn 0x10fcf at process virtual address 0x3fff86310000
Injecting memory failure for pfn 0x10fd0 at process virtual address 0x3fff86320000
Injecting memory failure for pfn 0x10fd1 at process virtual address 0x3fff86330000
Injecting memory failure for pfn 0x10fd2 at process virtual address 0x3fff86340000
Injecting memory failure for pfn 0x10fd3 at process virtual address 0x3fff86350000
Injecting memory failure for pfn 0x10fd4 at process virtual address 0x3fff86360000
Injecting memory failure for pfn 0x10fd5 at process virtual address 0x3fff86370000

Link: http://lkml.kernel.org/r/20170410084701.11248-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation: vm, add hugetlbfs reservation overview

Adding a brief overview of hugetlbfs reservation design and
implementation as an aid to those making code modifications in this
area.

Link: http://lkml.kernel.org/r/1491586995-13085-1-git-send-email-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, swap: remove unused function prototype

This is a code cleanup patch, no functionality changes.  There are 2
unused function prototype in swap.h, they are removed.

Link: http://lkml.kernel.org/r/20170405071017.23677-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcontrol: use node page state naming scheme for memcg

The memory controllers stat function names are awkwardly long and
arbitrarily different from the zone and node stat functions.

The current interface is named:

  mem_cgroup_read_stat()
  mem_cgroup_update_stat()
  mem_cgroup_inc_stat()
  mem_cgroup_dec_stat()
  mem_cgroup_update_page_stat()
  mem_cgroup_inc_page_stat()
  mem_cgroup_dec_page_stat()

This patch renames it to match the corresponding node stat functions:

  memcg_page_state() [node_page_state()]
  mod_memcg_state() [mod_node_state()]
  inc_memcg_state() [inc_node_state()]
  dec_memcg_state() [dec_node_state()]
  mod_memcg_page_state() [mod_node_page_state()]
  inc_memcg_page_state() [inc_node_page_state()]
  dec_memcg_page_state() [dec_node_page_state()]

Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcontrol: re-use node VM page state enum

The current duplication is a high-maintenance mess, and it's painful to
add new items or query memcg state from the rest of the VM.

This increases the size of the stat array marginally, but we should aim
to track all these stats on a per-cgroup level anyway.

Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcontrol: re-use global VM event enum

The current duplication is a high-maintenance mess, and it's painful to
add new items.

This increases the size of the event array, but we'll eventually want
most of the VM events tracked on a per-cgroup basis anyway.

Link: http://lkml.kernel.org/r/20170404220148.28338-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcontrol: clean up memory.events counting function

We only ever count single events, drop the @nr parameter.  Rename the
function accordingly.  Remove low-information kerneldoc.

Link: http://lkml.kernel.org/r/20170404220148.28338-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: vmscan: fix IO/refault regression in cache workingset transition

Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file
list") we noticed bigger IO spikes during changes in cache access
patterns.

The patch in question shrunk the inactive list size to leave more room
for the current workingset in the presence of streaming IO.  However,
workingset transitions that previously happened on the inactive list are
now pushed out of memory and incur more refaults to complete.

This patch disables active list protection when refaults are being
observed.  This accelerates workingset transitions, and allows more of
the new set to establish itself from memory, without eating into the
ability to protect the established workingset during stable periods.

The workloads that were measurably affected for us were hit pretty bad
by it, with refault/majfault rates doubling and tripling during cache
transitions, and the machines sustaining half-hour periods of 100% IO
utilization, where they'd previously have sub-minute peaks at 60-90%.

Stateful services that handle user data tend to be more conservative
with kernel upgrades.  As a result we hit most page cache issues with
some delay, as was the case here.

The severity seemed to warrant a stable tag.

Fixes: 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list")
Link: http://lkml.kernel.org/r/20170404220052.27593-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org> [4.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mmap: replace SHM_HUGE_MASK with MAP_HUGE_MASK inside mmap_pgoff

Commit 091d0d55b286 ("shm: fix null pointer deref when userspace
specifies invalid hugepage size") had replaced MAP_HUGE_MASK with
SHM_HUGE_MASK.  Though both of them contain the same numeric value of
0x3f, MAP_HUGE_MASK flag sounds more appropriate than the other one in
the context.  Hence change it back.

Link: http://lkml.kernel.org/r/20170404045635.616-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

oom: improve oom disable handling

Tetsuo has reported that sysrq triggered OOM killer will print a
misleading information when no tasks are selected:

  sysrq: SysRq : Manual OOM execution
  Out of memory: Kill process 4468 ((agetty)) score 0 or sacrifice child
  Killed process 4468 ((agetty)) total-vm:43704kB, anon-rss:1760kB, file-rss:0kB, shmem-rss:0kB
  sysrq: SysRq : Manual OOM execution
  Out of memory: Kill process 4469 (systemd-cgroups) score 0 or sacrifice child
  Killed process 4469 (systemd-cgroups) total-vm:10704kB, anon-rss:120kB, file-rss:0kB, shmem-rss:0kB
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled

The real reason is that there are no eligible tasks for the OOM killer
to select but since commit 7c5f64f84483 ("mm: oom: deduplicate victim
selection code for memcg and global oom") the semantic of out_of_memory
has changed without updating moom_callback.

This patch updates moom_callback to tell that no task was eligible which
is the case for both oom killer disabled and no eligible tasks.  In
order to help distinguish first case from the second add printk to both
oom_killer_{enable,disable}.  This information is useful on its own
because it might help debugging potential memory allocation failures.

Fixes: 7c5f64f84483 ("mm: oom: deduplicate victim selection code for memcg and global oom")
Link: http://lkml.kernel.org/r/20170404134705.6361-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

userfaultfd: selftest: combine all cases into a single executable

Currently, selftest for userfaultfd is compiled three times: for
anonymous, shared and hugetlb memory.  Let's combine all the cases into
a single executable which will have a command line option for selection
of the test type.

Link: http://lkml.kernel.org/r/1490869741-5913-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: fix spelling error

Fix variable name error in comments. No code changes.

Link: http://lkml.kernel.org/r/20170403161655.5081-1-haolee.swjtu@gmail.com
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swap_slots.c: add warning if swap slots cache failed to initialize

Add a warning diagnostics to user if we failed to allocate swap slots
cache and use it.

[akpm@linux-foundation.org: use WARN_ONCE return value, fix grammar in message]
Link: http://lkml.kernel.org/r/20170328234827.GA10107@linux.intel.com
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/migrate.h: add arg names to prototype

It is preferred, and the rest of migrate.h gets it right.

Link: http://lkml.kernel.org/r/1490336009-8024-1-git-send-email-pushkar.iit@gmail.com
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: enable page poisoning early at boot

On SPARSEMEM systems page poisoning is enabled after buddy is up,
because of the dependency on page extension init.  This causes the pages
released by free_all_bootmem not to be poisoned.  This either delays or
misses the identification of some issues because the pages have to
undergo another cycle of alloc-free-alloc for any corruption to be
detected.

Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON
flag.  Since all the free pages will now be poisoned, the flag need not
be verified before checking the poison during an alloc.

[vinmenon@codeaurora.org: fix Kconfig]
Link: http://lkml.kernel.org/r/1490878002-14423-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, swap: avoid lock swap_avail_lock when held cluster lock

Cluster lock is used to protect the swap_cluster_info and corresponding
elements in swap_info_struct->swap_map[].  But it is found that now in
scan_swap_map_slots(), swap_avail_lock may be acquired when cluster lock
is held.  This does no good except making the locking more complex and
improving the potential locking contention, because the
swap_info_struct->lock is used to protect the data structure operated in
the code already.  Fix this via moving the corresponding operations in
scan_swap_map_slots() out of cluster lock.

Link: http://lkml.kernel.org/r/20170317064635.12792-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, swap: improve readability via make spin_lock/unlock balanced

This is just a cleanup patch, no functionality change.

In cluster_list_add_tail(), spin_lock_nested() is used to lock the
cluster, while unlock_cluster() is used to unlock the cluster.  To
improve the code readability, use spin_unlock() directly to unlock the
cluster.

Link: http://lkml.kernel.org/r/20170317064635.12792-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, swap: fix comment in __read_swap_cache_async

Commit cbab0e4eec29 ("swap: avoid read_swap_cache_async() race to
deadlock while waiting on discard I/O completion") fixed a deadlock in
read_swap_cache_async().  Because at that time, in swap allocation path,
a swap entry may be set as SWAP_HAS_CACHE, then wait for discarding to
complete before the page for the swap entry is added to the swap cache.

But in commit 815c2c543d3a ("swap: make swap discard async"), the
discarding for swap become asynchronous, waiting for discarding to
complete will be done before the swap entry is set as SWAP_HAS_CACHE.
So the comments in code is incorrect now.  This patch fixes the
comments.

The cond_resched() added in the commit cbab0e4eec29 is not necessary now
too.  But if we added some sleep in swap allocation path in the future,
there may be some hard to debug/reproduce deadlock bug.  So it is kept.

Link: http://lkml.kernel.org/r/20170317064635.12792-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove SWAP_[SUCCESS|AGAIN|FAIL]

There is no user for it.  Remove it.

[minchan@kernel.org: use false instead of SWAP_FAIL]
Link: http://lkml.kernel.org/r/20170316053313.GA19241@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-11-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: make rmap_one boolean function

rmap_one's return value controls whether rmap_work should contine to
scan other ptes or not so it's target for changing to boolean.  Return
true if the scan should be continued.  Otherwise, return false to stop
the scanning.

This patch makes rmap_one's return value to boolean.

Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: make rmap_walk() return void

There is no user of the return value from rmap_walk() and friends so
this patch makes them void-returning functions.

Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: make ttu's return boolean

try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for
boolean return.  This patch changes it.

Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove SWAP_AGAIN in ttu

In 2002, [1] introduced SWAP_AGAIN.  At that time, try_to_unmap_one used
spin_trylock(&mm->page_table_lock) so it's really easy to contend and
fail to hold a lock so SWAP_AGAIN to keep LRU status makes sense.

However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN so
remove SWAP_AGAIN and just return SWAP_FAIL.

[1] c48c43e, minimal rmap

Link: http://lkml.kernel.org/r/1489555493-14659-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove SWAP_MLOCK in ttu

ttu doesn't need to return SWAP_MLOCK.  Instead, just return SWAP_FAIL
because it means the page is not-swappable so it should move to another
LRU list(active or unevictable).  putback friends will move it to right
list depending on the page's LRU flag.

Link: http://lkml.kernel.org/r/1489555493-14659-6-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: make try_to_munlock() return void

try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped the page has
VM_LOCKED flag.  In that time, VM set PG_mlocked to the page if the page
is not pte-mapped THP which cannot be mlocked, either.

With that, __munlock_isolated_page can use PageMlocked to check whether
try_to_munlock is successful or not without relying on try_to_munlock's
retval.  It helps to make try_to_unmap/try_to_unmap_one simple with
upcoming patches.

[minchan@kernel.org: remove PG_Mlocked VM_BUG_ON check]
Link: http://lkml.kernel.org/r/20170411025615.GA6545@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove SWAP_MLOCK check for SWAP_SUCCESS in ttu

If the page is mapped and rescue in try_to_unmap_one, the
page_mapcount() of a page cannot be zero, so the page_mapcount check in
try_to_unmap is enough to return SWAP_SUCCESS.  IOW, SWAP_MLOCK check is
redundant so remove it.

Link: http://lkml.kernel.org/r/1489555493-14659-4-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove SWAP_DIRTY in ttu

If we found lazyfree page is dirty, try_to_unmap_one can just
SetPageSwapBakced in there like PG_mlocked page and just return with
SWAP_FAIL which is very natural because the page is not swappable right
now so that vmscan can activate it.  There is no point to introduce new
return value SWAP_DIRTY in try_to_unmap at the moment.

Link: http://lkml.kernel.org/r/1489555493-14659-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove unncessary ret in page_referenced

Nobody uses ret variable. Remove it.

Link: http://lkml.kernel.org/r/1489555493-14659-2-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmscan: more restrictive condition for retry in do_try_to_free_pages

By reviewing code, I find that when enter do_try_to_free_pages, the
may_thrash is always clear, and it will retry shrink zones to tap
cgroup's reserves memory by setting may_thrash when the former
shrink_zones reclaim nothing.

However, when memcg is disabled or on legacy hierarchy, or there do not
have any memcg protected by low limit, it should not do this useless
retry at all, for we do not have any cgroup's reserves memory to tap,
and we have already done hard work but made no progress, which as Michal
pointed out in former version, we are trying hard to control the retry
logical of page alloctor, and the current additional round of reclaim is
just lame.

Therefore, to avoid this unneeded retrying and make code more readable,
we remove the may_thrash field in scan_control, instead, introduce
memcg_low_reclaim and memcg_low_skipped, and only retry when
memcg_low_skipped, by setting memcg_low_reclaim.

[xieyisheng1@huawei.com: remove may_thrash field, introduce mem_cgroup_reclaim]
Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com
Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Suggested-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/compaction: ignore block suitable after check large free page

By reviewing code, I find that if the migrate target is a large free
page and we ignore suitable, it may splite large target free page into
smaller block which is not good for defrag.  So move the ignore block
suitable after check large free page.

As Vlastimil pointed out in RFC version that this patch is just based on
logical analyses which might be better for future-proofing the function
and it is most likely won't have any visible effect right now, for
direct compaction shouldn't have to be called if there's a
>=pageblock_order page already available.

Link: http://lkml.kernel.org/r/1489490743-5364-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/sparse: refine usemap_size() a little

The current implementation calculates usemap_size in two steps:
    * calculate number of bytes to cover these bits
    * calculate number of "unsigned long" to cover these bytes

It would be more clear by:
    * calculate number of "unsigned long" to cover these bits
    * multiple it with sizeof(unsigned long)

This patch refine usemap_size() a little to make it more easy to
understand.

Link: http://lkml.kernel.org/r/20170310043713.96871-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: page_alloc: __GFP_NOWARN shouldn't suppress stall warnings

__GFP_NOWARN, which is usually added to avoid warnings from callsites
that expect to fail and have fallbacks, currently also suppresses
allocation stall warnings.  These trigger when an allocation is stuck
inside the allocator for 10 seconds or longer.

But there is no class of allocations that can get legitimately stuck in
the allocator for this long.  This always indicates a problem.

Always emit stall warnings.  Restrict __GFP_NOWARN to alloc failures.

Link: http://lkml.kernel.org/r/20170125181150.GA16398@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx

kswapd is woken to reclaim a node based on a failed allocation request
from any eligible zone.  Once reclaiming in balance_pgdat(), it will
continue reclaiming until there is an eligible zone available for the
zone it was woken for.  kswapd tracks what zone it was recently woken
for in pgdat->kswapd_classzone_idx.  If it has not been woken recently,
this zone will be 0.

However, the decision on whether to sleep is made on
kswapd_classzone_idx which is 0 without a recent wakeup request and that
classzone does not account for lowmem reserves.  This allows kswapd to
sleep when a low small zone such as ZONE_DMA is balanced for a GFP_DMA
request even if a stream of allocations cannot use that zone.  While
kswapd may be woken again shortly in the near future there are two
consequences -- the pgdat bits that control congestion are cleared
prematurely and direct reclaim is more likely as kswapd slept
prematurely.

This patch flips kswapd_classzone_idx to default to MAX_NR_ZONES (an
invalid index) when there has been no recent wakeups.  If there are no
wakeups, it'll decide whether to sleep based on the highest possible
zone available (MAX_NR_ZONES - 1).  It then becomes critical that the
"pgdat balanced" decisions during reclaim and when deciding to sleep are
the same.  If there is a mismatch, kswapd can stay awake continually
trying to balance tiny zones.

simoop was used to evaluate it again.  Two of the preparation patches
regressed the workload so they are included as the second set of
results.  Otherwise this patch looks artifically excellent

                                         4.11.0-rc1            4.11.0-rc1            4.11.0-rc1
                                            vanilla              clear-v2          keepawake-v2
Amean    p50-Read             21670074.18 (  0.00%) 19786774.76 (  8.69%) 22668332.52 ( -4.61%)
Amean    p95-Read             25456267.64 (  0.00%) 24101956.27 (  5.32%) 26738688.00 ( -5.04%)
Amean    p99-Read             29369064.73 (  0.00%) 27691872.71 (  5.71%) 30991404.52 ( -5.52%)
Amean    p50-Write                1390.30 (  0.00%)     1011.91 ( 27.22%)      924.91 ( 33.47%)
Amean    p95-Write              412901.57 (  0.00%)    34874.98 ( 91.55%)     1362.62 ( 99.67%)
Amean    p99-Write             6668722.09 (  0.00%)   575449.60 ( 91.37%)    16854.04 ( 99.75%)
Amean    p50-Allocation          78714.31 (  0.00%)    84246.26 ( -7.03%)    74729.74 (  5.06%)
Amean    p95-Allocation         175533.51 (  0.00%)   400058.43 (-127.91%)   101609.74 ( 42.11%)
Amean    p99-Allocation         247003.02 (  0.00%) 10905600.00 (-4315.17%)   125765.57 ( 49.08%)

With this patch on top, write and allocation latencies are massively
improved.  The read latencies are slightly impaired but it's worth
noting that this is mostly due to the IO scheduler and not directly
related to reclaim.  The vmstats are a bit of a mix but the relevant
ones are as follows;

                            4.10.0-rc7  4.10.0-rc7  4.10.0-rc7
                          mmots-20170209 clear-v1r25keepawake-v1r25
Swap Ins                             0           0           0
Swap Outs                            0         608           0
Direct pages scanned           6910672     3132699     6357298
Kswapd pages scanned          57036946    82488665    56986286
Kswapd pages reclaimed        55993488    63474329    55939113
Direct pages reclaimed         6905990     2964843     6352115
Kswapd efficiency                  98%         76%         98%
Kswapd velocity              12494.375   17597.507   12488.065
Direct efficiency                  99%         94%         99%
Direct velocity               1513.835     668.306    1393.148
Page writes by reclaim           0.000 4410243.000       0.000
Page writes file                     0     4409635           0
Page writes anon                     0         608           0
Page reclaim immediate         1036792    14175203     1042571

                            4.11.0-rc1  4.11.0-rc1  4.11.0-rc1
                               vanilla  clear-v2  keepawake-v2
Swap Ins                             0          12           0
Swap Outs                            0         838           0
Direct pages scanned           6579706     3237270     6256811
Kswapd pages scanned          61853702    79961486    54837791
Kswapd pages reclaimed        60768764    60755788    53849586
Direct pages reclaimed         6579055     2987453     6256151
Kswapd efficiency                  98%         75%         98%
Page writes by reclaim           0.000 4389496.000       0.000
Page writes file                     0     4388658           0
Page writes anon                     0         838           0
Page reclaim immediate         1073573    14473009      982507

Swap-outs are equivalent to baseline.

Direct reclaim is reduced but not eliminated.  It's worth noting that
there are two periods of direct reclaim for this workload.  The first is
when it switches from preparing the files for the actual test itself.
It's a lot of file IO followed by a lot of allocs that reclaims heavily
for a brief window.  While direct reclaim is lower with clear-v2, it is
due to kswapd scanning aggressively and trying to reclaim the world
which is not the right thing to do.  With the patches applied, there is
still direct reclaim but the phase change from "creating work files" to
starting multiple threads that allocate a lot of anonymous memory faster
than kswapd can reclaim.

Scanning/reclaim efficiency is restored by this patch.

Page writes from reclaim context are back at 0 which is ideal.

Pages immediately reclaimed after IO completes is slightly improved but
it is expected this will vary slightly.

On UMA, there is almost no change so this is not expected to be a
universal win.

[mgorman@suse.de: fix ->kswapd_classzone_idx initialization]
Link: http://lkml.kernel.org/r/20170406174538.5msrznj6nt6qpbx5@suse.de
Link: http://lkml.kernel.org/r/20170309075657.25121-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, vmscan: only clear pgdat congested/dirty/writeback state when balanced

A pgdat tracks if recent reclaim encountered too many dirty, writeback
or congested pages.  The flags control whether kswapd writes pages back
from reclaim context, tags pages for immediate reclaim when IO
completes, whether processes block on wait_iff_congested and whether
kswapd blocks when too many pages marked for immediate reclaim are
encountered.

The state is cleared in a check function with side-effects.  With the
patch "mm, vmscan: fix zone balance check in prepare_kswapd_sleep", the
timing of when the bits get cleared changed.  Due to the way the check
works, it'll clear the bits if ZONE_DMA is balanced for a GFP_DMA
allocation because it does not account for lowmem reserves properly.

For the simoop workload, kswapd is not stalling when it should due to
the premature clearing, writing pages from reclaim context like crazy
and generally being unhelpful.

This patch resets the pgdat bits related to page reclaim only when
kswapd is going to sleep.  The comparison with simoop is then

                                         4.11.0-rc1            4.11.0-rc1            4.11.0-rc1
                                            vanilla           fixcheck-v2              clear-v2
Amean    p50-Read             21670074.18 (  0.00%) 20464344.18 (  5.56%) 19786774.76 (  8.69%)
Amean    p95-Read             25456267.64 (  0.00%) 25721423.64 ( -1.04%) 24101956.27 (  5.32%)
Amean    p99-Read             29369064.73 (  0.00%) 30174230.76 ( -2.74%) 27691872.71 (  5.71%)
Amean    p50-Write                1390.30 (  0.00%)     1395.28 ( -0.36%)     1011.91 ( 27.22%)
Amean    p95-Write              412901.57 (  0.00%)    37737.74 ( 90.86%)    34874.98 ( 91.55%)
Amean    p99-Write             6668722.09 (  0.00%)   666489.04 ( 90.01%)   575449.60 ( 91.37%)
Amean    p50-Allocation          78714.31 (  0.00%)    86286.22 ( -9.62%)    84246.26 ( -7.03%)
Amean    p95-Allocation         175533.51 (  0.00%)   351812.27 (-100.42%)   400058.43 (-127.91%)
Amean    p99-Allocation         247003.02 (  0.00%)  6291171.56 (-2447.00%) 10905600.00 (-4315.17%)

Read latency is improved, write latency is mostly improved but
allocation latency is regressed.  kswapd is still reclaiming
inefficiently, pages are being written back from writeback context and a
host of other issues.  However, given the change, it needed to be
spelled out why the side-effect was moved.

Link: http://lkml.kernel.org/r/20170309075657.25121-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, vmscan: fix zone balance check in prepare_kswapd_sleep

Patch series "Reduce amount of time kswapd sleeps prematurely", v2.

The series is unusual in that the first patch fixes one problem and
introduces other issues that are noted in the changelog.  Patch 2 makes
a minor modification that is worth considering on its own but leaves the
kernel in a state where it behaves badly.  It's not until patch 3 that
there is an improvement against baseline.

This was mostly motivated by examining Chris Mason's "simoop" benchmark
which puts the VM under similar pressure to HADOOP.  It has been
reported that the benchmark has regressed severely during the last
number of releases.  While I cannot reproduce all the same problems
Chris experienced due to hardware limitations, there was a number of
problems on a 2-socket machine with a single disk.

simoop latencies
                                         4.11.0-rc1            4.11.0-rc1
                                            vanilla          keepawake-v2
Amean    p50-Read             21670074.18 (  0.00%) 22668332.52 ( -4.61%)
Amean    p95-Read             25456267.64 (  0.00%) 26738688.00 ( -5.04%)
Amean    p99-Read             29369064.73 (  0.00%) 30991404.52 ( -5.52%)
Amean    p50-Write                1390.30 (  0.00%)      924.91 ( 33.47%)
Amean    p95-Write              412901.57 (  0.00%)     1362.62 ( 99.67%)
Amean    p99-Write             6668722.09 (  0.00%)    16854.04 ( 99.75%)
Amean    p50-Allocation          78714.31 (  0.00%)    74729.74 (  5.06%)
Amean    p95-Allocation         175533.51 (  0.00%)   101609.74 ( 42.11%)
Amean    p99-Allocation         247003.02 (  0.00%)   125765.57 ( 49.08%)

These are latencies.  Read/write are threads reading fixed-size random
blocks from a simulated database.  The allocation latency is mmaping and
faulting regions of memory.  The p50, 95 and p99 reports the worst
latencies for 50% of the samples, 95% and 99% respectively.

For example, the report indicates that while the test was running 99% of
writes completed 99.75% faster.  It's worth noting that on a UMA machine
that no difference in performance with simoop was observed so milage
will vary.

It's noted that there is a slight impact to read latencies but it's
mostly due to IO scheduler decisions and offset by the large reduction
in other latencies.

This patch (of 3):

The check in prepare_kswapd_sleep needs to match the one in
balance_pgdat since the latter will return as soon as any one of the
zones in the classzone is above the watermark.  This is specially
important for higher order allocations since balance_pgdat will
typically reset the order to zero relying on compaction to create the
higher order pages.  Without this patch, prepare_kswapd_sleep fails to
wake up kcompactd since the zone balance check fails.

It was first reported against 4.9.7 that kswapd is failing to wake up
kcompactd due to a mismatch in the zone balance check between
balance_pgdat() and prepare_kswapd_sleep().

balance_pgdat() returns as soon as a single zone satisfies the
allocation but prepare_kswapd_sleep() requires all zones to do +the
same.  This causes prepare_kswapd_sleep() to never succeed except in the
order == 0 case and consequently, wakeup_kcompactd() is never called.
For the machine that originally motivated this patch, the state of
compaction from /proc/vmstat looked this way after a day and a half +of
uptime:

compact_migrate_scanned 240496
compact_free_scanned 76238632
compact_isolated 123472
compact_stall 1791
compact_fail 29
compact_success 1762
compact_daemon_wake 0

After applying the patch and about 10 hours of uptime the state looks
like this:

compact_migrate_scanned 59927299
compact_free_scanned 2021075136
compact_isolated 640926
compact_stall 4
compact_fail 2
compact_success 2
compact_daemon_wake 5160

Further notes from Mel that motivated him to pick this patch up and
resend it;

It was observed for the simoop workload (pressures the VM similar to
HADOOP) that kswapd was failing to keep ahead of direct reclaim.  The
investigation noted that there was a need to rationalise kswapd
decisions to reclaim with kswapd decisions to sleep.  With this patch on
a 2-socket box, there was a 49% reduction in direct reclaim scanning.

However, the impact otherwise is extremely negative.  Kswapd reclaim
efficiency dropped from 98% to 76%.  simoop has three latency-related
metrics for read, write and allocation (an anonymous mmap and fault).

                                         4.11.0-rc1            4.11.0-rc1
                                            vanilla           fixcheck-v2
Amean    p50-Read             21670074.18 (  0.00%) 20464344.18 (  5.56%)
Amean    p95-Read             25456267.64 (  0.00%) 25721423.64 ( -1.04%)
Amean    p99-Read             29369064.73 (  0.00%) 30174230.76 ( -2.74%)
Amean    p50-Write                1390.30 (  0.00%)     1395.28 ( -0.36%)
Amean    p95-Write              412901.57 (  0.00%)    37737.74 ( 90.86%)
Amean    p99-Write             6668722.09 (  0.00%)   666489.04 ( 90.01%)
Amean    p50-Allocation          78714.31 (  0.00%)    86286.22 ( -9.62%)
Amean    p95-Allocation         175533.51 (  0.00%)   351812.27 (-100.42%)
Amean    p99-Allocation         247003.02 (  0.00%)  6291171.56 (-2447.00%)

Of greater concern is that the patch causes swapping and page writes
from kswapd context rose from 0 pages to 4189753 pages during the hour
the workload ran for.  By and large, the patch has very bad behaviour
but easily missed as the impact on a UMA machine is negligible.

This patch is included with the data in case a bisection leads to this
area.  This patch is also a pre-requisite for the rest of the series.

Link: http://lkml.kernel.org/r/20170309075657.25121-2-mgorman@techsingularity.net
Signed-off-by: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: do not use double negation for testing page flags

With the discussion[1], I found it seems there are every PageFlags
functions return bool at this moment so we don't need double negation
any more.  Although it's not a problem to keep it, it makes future users
confused to use double negation for them, too.

Remove such possibility.

[1] https://marc.info/?l=linux-kernel&m=148881578820434

Frankly sepaking, I like every PageFlags to return bool instead of int.
It will make it clear.  AFAIR, Chen Gang had tried it but don't know why
it was not merged at that time.

http://lkml.kernel.org/r/1469336184-1904-1-git-send-email-chengang@emindsoft.com.cn

Link: http://lkml.kernel.org/r/1488868597-32222-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove rodata_test_data export, add pr_fmt

Since commit 3ad38ceb2769 ("x86/mm: Remove CONFIG_DEBUG_NX_TEST"),
nothing is using the exported rodata_test_data variable, so drop the
export.

This additionally updates the pr_fmt to avoid redundant strings and
adjusts some whitespace.

Link: http://lkml.kernel.org/r/20170307005313.GA85809@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: tighten up the fault path a little

The round_up() macro generates a couple of unnecessary instructions
in this usage:

    48cd:       49 8b 47 50             mov    0x50(%r15),%rax
    48d1:       48 83 e8 01             sub    $0x1,%rax
    48d5:       48 0d ff 0f 00 00       or     $0xfff,%rax
    48db:       48 83 c0 01             add    $0x1,%rax
    48df:       48 c1 f8 0c             sar    $0xc,%rax
    48e3:       48 39 c3                cmp    %rax,%rbx
    48e6:       72 2e                   jb     4916 <filemap_fault+0x96>

If we change round_up() to ((x) + __round_mask(x, y)) & ~__round_mask(x, y)
then GCC can see through it and remove the mask (because that would be
dead code given the subsequent shift):

    48cd:       49 8b 47 50             mov    0x50(%r15),%rax
    48d1:       48 05 ff 0f 00 00       add    $0xfff,%rax
    48d7:       48 c1 e8 0c             shr    $0xc,%rax
    48db:       48 39 c3                cmp    %rax,%rbx
    48de:       72 2e                   jb     490e <filemap_fault+0x8e>

But that's problematic because we'd evaluate 'y' twice.  Converting
round_up into an inline function prevents it from being used in other
definitions.  The easiest thing to do is just change these three usages
of round_up to use DIV_ROUND_UP.  Also add an unlikely() because GCC's
heuristic is wrong in this case.

Link: http://lkml.kernel.org/r/20170207192812.5281-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

jbd2: make the whole kjournald2 kthread NOFS safe

kjournald2 is central to the transaction commit processing.  As such any
potential allocation from this kernel thread has to be GFP_NOFS.  Make
sure to mark the whole kernel thread GFP_NOFS by the memalloc_nofs_save.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170306131408.9828-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

jbd2: mark the transaction context with the scope GFP_NOFS context

now that we have memalloc_nofs_{save,restore} api we can mark the whole
transaction context as implicitly GFP_NOFS.  All allocations will
automatically inherit GFP_NOFS this way.  This means that we do not have
to mark any of those requests with GFP_NOFS and moreover all the
ext4_kv[mz]alloc(GFP_NOFS) are also safe now because even the hardcoded
GFP_KERNEL allocations deep inside the vmalloc will be NOFS now.

[akpm@linux-foundation.org: tweak comments]
Link: http://lkml.kernel.org/r/20170306131408.9828-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio*

kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
API to prevent from reclaim recursion into the fs because vmalloc can
invoke unconditional GFP_KERNEL allocations and these functions might be
called from the NOFS contexts.  The memalloc_noio_save will enforce
GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
unnecessary.  Let's use memalloc_nofs_{save,restore} instead as it
should provide exactly what we need here - implicit GFP_NOFS context.

Link: http://lkml.kernel.org/r/20170306131408.9828-6-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: introduce memalloc_nofs_{save,restore} API

GFP_NOFS context is used for the following 5 reasons currently:

 - to prevent from deadlocks when the lock held by the allocation
   context would be needed during the memory reclaim

 - to prevent from stack overflows during the reclaim because the
   allocation is performed from a deep context already

 - to prevent lockups when the allocation context depends on other
   reclaimers to make a forward progress indirectly

 - just in case because this would be safe from the fs POV

 - silence lockdep false positives

Unfortunately overuse of this allocation context brings some problems to
the MM.  Memory reclaim is much weaker (especially during heavy FS
metadata workloads), OOM killer cannot be invoked because the MM layer
doesn't have enough information about how much memory is freeable by the
FS layer.

In many cases it is far from clear why the weaker context is even used
and so it might be used unnecessarily.  We would like to get rid of
those as much as possible.  One way to do that is to use the flag in
scopes rather than isolated cases.  Such a scope is declared when really
necessary, tracked per task and all the allocation requests from within
the context will simply inherit the GFP_NOFS semantic.

Not only this is easier to understand and maintain because there are
much less problematic contexts than specific allocation requests, this
also helps code paths where FS layer interacts with other layers (e.g.
crypto, security modules, MM etc...) and there is no easy way to convey
the allocation context between the layers.

Introduce memalloc_nofs_{save,restore} API to control the scope of
GFP_NOFS allocation context.  This is basically copying
memalloc_noio_{save,restore} API we have for other restricted allocation
context GFP_NOIO.  The PF_MEMALLOC_NOFS flag already exists and it is
just an alias for PF_FSTRANS which has been xfs specific until recently.
There are no more PF_FSTRANS users anymore so let's just drop it.

PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS
implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO.  memalloc_noio_flags
is renamed to current_gfp_context because it now cares about both
PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts.  Xfs code paths preserve
their semantic.  kmem_flags_convert() doesn't need to evaluate the flag
anymore.

This patch shouldn't introduce any functional changes.

Let's hope that filesystems will drop direct GFP_NOFS (resp.  ~__GFP_FS)
usage as much as possible and only use a properly documented
memalloc_nofs_{save,restore} checkpoints where they are appropriate.

[akpm@linux-foundation.org: fix comment typo, reflow comment]
Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS

xfs has defined PF_FSTRANS to declare a scope GFP_NOFS semantic quite
some time ago.  We would like to make this concept more generic and use
it for other filesystems as well.  Let's start by giving the flag a more
generic name PF_MEMALLOC_NOFS which is in line with an exiting
PF_MEMALLOC_NOIO already used for the same purpose for GFP_NOIO
contexts.  Replace all PF_FSTRANS usage from the xfs code in the first
step before we introduce a full API for it as xfs uses the flag directly
anyway.

This patch doesn't introduce any functional change.

Link: http://lkml.kernel.org/r/20170306131408.9828-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lockdep: allow to disable reclaim lockup detection

The current implementation of the reclaim lockup detection can lead to
false positives and those even happen and usually lead to tweak the code
to silence the lockdep by using GFP_NOFS even though the context can use
__GFP_FS just fine.

See

  http://lkml.kernel.org/r/20160512080321.GA18496@dastard

as an example.

  =================================
  [ INFO: inconsistent lock state ]
  4.5.0-rc2+ #4 Tainted: G           O
  ---------------------------------
  inconsistent {RECLAIM_FS-ON-R} -> {IN-RECLAIM_FS-W} usage.
  kswapd0/543 [HC0[0]:SC0[0]:HE1:SE1] takes:

  (&xfs_nondir_ilock_class){++++-+}, at: xfs_ilock+0x177/0x200 [xfs]

  {RECLAIM_FS-ON-R} state was registered at:
    mark_held_locks+0x79/0xa0
    lockdep_trace_alloc+0xb3/0x100
    kmem_cache_alloc+0x33/0x230
    kmem_zone_alloc+0x81/0x120 [xfs]
    xfs_refcountbt_init_cursor+0x3e/0xa0 [xfs]
    __xfs_refcount_find_shared+0x75/0x580 [xfs]
    xfs_refcount_find_shared+0x84/0xb0 [xfs]
    xfs_getbmap+0x608/0x8c0 [xfs]
    xfs_vn_fiemap+0xab/0xc0 [xfs]
    do_vfs_ioctl+0x498/0x670
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x12/0x6f

         CPU0
         ----
    lock(&xfs_nondir_ilock_class);
    <Interrupt>
      lock(&xfs_nondir_ilock_class);

   *** DEADLOCK ***

  3 locks held by kswapd0/543:

  stack backtrace:
  CPU: 0 PID: 543 Comm: kswapd0 Tainted: G           O    4.5.0-rc2+ #4
  Call Trace:
   lock_acquire+0xd8/0x1e0
   down_write_nested+0x5e/0xc0
   xfs_ilock+0x177/0x200 [xfs]
   xfs_reflink_cancel_cow_range+0x150/0x300 [xfs]
   xfs_fs_evict_inode+0xdc/0x1e0 [xfs]
   evict+0xc5/0x190
   dispose_list+0x39/0x60
   prune_icache_sb+0x4b/0x60
   super_cache_scan+0x14f/0x1a0
   shrink_slab.part.63.constprop.79+0x1e9/0x4e0
   shrink_zone+0x15e/0x170
   kswapd+0x4f1/0xa80
   kthread+0xf2/0x110
   ret_from_fork+0x3f/0x70

To quote Dave:
 "Ignoring whether reflink should be doing anything or not, that's a
  "xfs_refcountbt_init_cursor() gets called both outside and inside
  transactions" lockdep false positive case. The problem here is lockdep
  has seen this allocation from within a transaction, hence a GFP_NOFS
  allocation, and now it's seeing it in a GFP_KERNEL context. Also note
  that we have an active reference to this inode.

  So, because the reclaim annotations overload the interrupt level
  detections and it's seen the inode ilock been taken in reclaim
  ("interrupt") context, this triggers a reclaim context warning where
  it thinks it is unsafe to do this allocation in GFP_KERNEL context
  holding the inode ilock..."

This sounds like a fundamental problem of the reclaim lock detection.
It is really impossible to annotate such a special usecase IMHO unless
the reclaim lockup detection is reworked completely.  Until then it is
much better to provide a way to add "I know what I am doing flag" and
mark problematic places.  This would prevent from abusing GFP_NOFS flag
which has a runtime effect even on configurations which have lockdep
disabled.

Introduce __GFP_NOLOCKDEP flag which tells the lockdep gfp tracking to
skip the current allocation request.

While we are at it also make sure that the radix tree doesn't
accidentaly override tags stored in the upper part of the gfp_mask.

Link: http://lkml.kernel.org/r/20170306131408.9828-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lockdep: teach lockdep about memalloc_noio_save

Patch series "scope GFP_NOFS api", v5.

This patch (of 7):

Commit 21caf2fc1931 ("mm: teach mm by current context info to not do I/O
during memory allocation") added the memalloc_noio_(save|restore)
functions to enable people to modify the MM behavior by disabling I/O
during memory allocation.

This was further extended in commit 934f3072c17c ("mm: clear __GFP_FS
when PF_MEMALLOC_NOIO is set").

memalloc_noio_* functions prevent allocation paths recursing back into
the filesystem without explicitly changing the flags for every
allocation site.

However, lockdep hasn't been keeping up with the changes and it entirely
misses handling the memalloc_noio adjustments.  Instead, it is left to
the callers of __lockdep_trace_alloc to call the function after they
have shaven the respective GFP flags which can lead to false positives:

  =================================
   [ INFO: inconsistent lock state ]
   4.10.0-nbor #134 Not tainted
   ---------------------------------
   inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
   fsstress/3365 [HC0[0]:SC0[0]:HE1:SE1] takes:
    (&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230
   {IN-RECLAIM_FS-W} state was registered at:
     __lock_acquire+0x62a/0x17c0
     lock_acquire+0xc5/0x220
     down_write_nested+0x4f/0x90
     xfs_ilock+0x141/0x230
     xfs_reclaim_inode+0x12a/0x320
     xfs_reclaim_inodes_ag+0x2c8/0x4e0
     xfs_reclaim_inodes_nr+0x33/0x40
     xfs_fs_free_cached_objects+0x19/0x20
     super_cache_scan+0x191/0x1a0
     shrink_slab+0x26f/0x5f0
     shrink_node+0xf9/0x2f0
     kswapd+0x356/0x920
     kthread+0x10c/0x140
     ret_from_fork+0x31/0x40
   irq event stamp: 173777
   hardirqs last  enabled at (173777): __local_bh_enable_ip+0x70/0xc0
   hardirqs last disabled at (173775): __local_bh_enable_ip+0x37/0xc0
   softirqs last  enabled at (173776): _xfs_buf_find+0x67a/0xb70
   softirqs last disabled at (173774): _xfs_buf_find+0x5db/0xb70

   other info that might help us debug this:
    Possible unsafe locking scenario:

          CPU0
          ----
     lock(&xfs_nondir_ilock_class);
     <Interrupt>
       lock(&xfs_nondir_ilock_class);

    *** DEADLOCK ***

   4 locks held by fsstress/3365:
    #0:  (sb_writers#10){++++++}, at: mnt_want_write+0x24/0x50
    #1:  (&sb->s_type->i_mutex_key#12){++++++}, at: vfs_setxattr+0x6f/0xb0
    #2:  (sb_internal#2){++++++}, at: xfs_trans_alloc+0xfc/0x140
    #3:  (&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230

   stack backtrace:
   CPU: 0 PID: 3365 Comm: fsstress Not tainted 4.10.0-nbor #134
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
   Call Trace:
    kmem_cache_alloc_node_trace+0x3a/0x2c0
    vm_map_ram+0x2a1/0x510
    _xfs_buf_map_pages+0x77/0x140
    xfs_buf_get_map+0x185/0x2a0
    xfs_attr_rmtval_set+0x233/0x430
    xfs_attr_leaf_addname+0x2d2/0x500
    xfs_attr_set+0x214/0x420
    xfs_xattr_set+0x59/0xb0
    __vfs_setxattr+0x76/0xa0
    __vfs_setxattr_noperm+0x5e/0xf0
    vfs_setxattr+0xae/0xb0
    setxattr+0x15e/0x1a0
    path_setxattr+0x8f/0xc0
    SyS_lsetxattr+0x11/0x20
    entry_SYSCALL_64_fastpath+0x23/0xc6

Let's fix this by making lockdep explicitly do the shaving of respective
GFP flags.

Fixes: 934f3072c17c ("mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set")
Link: http://lkml.kernel.org/r/20170306131408.9828-2-mhocko@kernel.org
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, vmstat: suppress pcp stats for unpopulated zones in zoneinfo

After "mm, vmstat: print non-populated zones in zoneinfo",
/proc/zoneinfo will show unpopulated zones.

The per-cpu pageset statistics are not relevant for unpopulated zones
and can be potentially lengthy, so supress them when they are not
interesting.

Also moves lowmem reserve protection information above pcp stats since
it is relevant for all zones per vm.lowmem_reserve_ratio.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703061400500.46428@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, vmstat: print non-populated zones in zoneinfo

Initscripts can use the information (protection levels) from
/proc/zoneinfo to configure vm.lowmem_reserve_ratio at boot.

vm.lowmem_reserve_ratio is an array of ratios for each configured zone
on the system.  If a zone is not populated on an arch, /proc/zoneinfo
suppresses its output.

This results in there not being a 1:1 mapping between the set of zones
emitted by /proc/zoneinfo and the zones configured by
vm.lowmem_reserve_ratio.

This patch shows statistics for non-populated zones in /proc/zoneinfo.
The zones exist and hold a spot in the vm.lowmem_reserve_ratio array.
Without this patch, it is not possible to determine which index in the
array controls which zone if one or more zones on the system are not
populated.

Remaining users of walk_zones_in_node() are unchanged.  Files such as
/proc/pagetypeinfo require certain zone data to be initialized properly
for display, which is not done for unpopulated zones.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703031451310.98023@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: use is_migrate_isolate_page() to simplify the code

Use is_migrate_isolate_page() to simplify the code, no functional
changes.

Link: http://lkml.kernel.org/r/58B94FB1.8020802@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: use is_migrate_highatomic() to simplify the code

Introduce two helpers, is_migrate_highatomic() and is_migrate_highatomic_page().

Simplify the code, no functional changes.

[akpm@linux-foundation.org: use static inlines rather than macros, per mhocko]
Link: http://lkml.kernel.org/r/58B94F15.6060606@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, swap: Fix a race in free_swap_and_cache()

Before using cluster lock in free_swap_and_cache(), the
swap_info_struct->lock will be held during freeing the swap entry and
acquiring page lock, so the page swap count will not change when testing
page information later.  But after using cluster lock, the cluster lock
(or swap_info_struct->lock) will be held only during freeing the swap
entry.  So before acquiring the page lock, the page swap count may be
changed in another thread.  If the page swap count is not 0, we should
not delete the page from the swap cache.  This is fixed via checking
page swap count again after acquiring the page lock.

I found the race when I review the code, so I didn't trigger the race
via a test program.  If the race occurs for an anonymous page shared by
multiple processes via fork, multiple pages will be allocated and
swapped in from the swap device for the previously shared one page.
That is, the user-visible runtime effect is more memory will be used and
the access latency for the page will be higher, that is, the performance
regression.

Link: http://lkml.kernel.org/r/20170301143905.12846-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: memcontrol: provide shmem statistics

Cgroups currently don't report how much shmem they use, which can be
useful data to have, in particular since shmem is included in the
cache/file item while being reclaimed like anonymous memory.

Add a counter to track shmem pages during charging and uncharging.

Link: http://lkml.kernel.org/r/20170221164343.32252-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Chris Down <cdown@fb.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

proc: show MADV_FREE pages info in smaps

Show MADV_FREE pages info of each vma in smaps.  The interface is for
diganose or monitoring purpose, userspace could use it to understand
what happens in the application.  Since userspace could dirty MADV_FREE
pages without notice from kernel, this interface is the only place we
can get accurate accounting info about MADV_FREE pages.

[mhocko@kernel.org: update Documentation/filesystems/proc.txt]
Link: http://lkml.kernel.org/r/89efde633559de1ec07444f2ef0f4963a97a2ce8.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: enable MADV_FREE for swapless system

Now MADV_FREE pages can be easily reclaimed even for swapless system.
We can safely enable MADV_FREE for all systems.

Link: http://lkml.kernel.org/r/155648585589300bfae1d45078e7aebb3d988b87.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: fix lazyfree BUG_ON check in try_to_unmap_one()

If a page is swapbacked, it means it should be in swapcache in
try_to_unmap_one's path.

If a page is !swapbacked, it mean it shouldn't be in swapcache in
try_to_unmap_one's path.

Check both two cases all at once and if it fails, warn and return
SWAP_FAIL.  Such bug never mean we should shut down the kernel.

[minchan@kernel.org: do not use VM_WARN_ON_ONCE as if condition[
Link: http://lkml.kernel.org/r/20170309060226.GB854@bbox
Link: http://lkml.kernel.org/r/20170307055551.GC29458@bbox
Signed-off-by: Minchan Kim <minchan@kernel.org>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: reclaim MADV_FREE pages

When memory pressure is high, we free MADV_FREE pages.  If the pages are
not dirty in pte, the pages could be freed immediately.  Otherwise we
can't reclaim them.  We put the pages back to anonumous LRU list (by
setting SwapBacked flag) and the pages will be reclaimed in normal
swapout way.

We use normal page reclaim policy.  Since MADV_FREE pages are put into
inactive file list, such pages and inactive file pages are reclaimed
according to their age.  This is expected, because we don't want to
reclaim too many MADV_FREE pages before used once pages.

Based on Minchan's original patch

[minchan@kernel.org: clean up lazyfree page handling]
Link: http://lkml.kernel.org/r/20170303025237.GB3503@bbox
Link: http://lkml.kernel.org/r/14b8eb1d3f6bf6cc492833f183ac8c304e560484.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: move MADV_FREE pages into LRU_INACTIVE_FILE list

madv()'s MADV_FREE indicate pages are 'lazyfree'.  They are still
anonymous pages, but they can be freed without pageout.  To distinguish
these from normal anonymous pages, we clear their SwapBacked flag.

MADV_FREE pages could be freed without pageout, so they pretty much like
used once file pages.  For such pages, we'd like to reclaim them once
there is memory pressure.  Also it might be unfair reclaiming MADV_FREE
pages always before used once file pages and we definitively want to
reclaim the pages before other anonymous and file pages.

To speed up MADV_FREE pages reclaim, we put the pages into
LRU_INACTIVE_FILE list.  The rationale is LRU_INACTIVE_FILE list is tiny
nowadays and should be full of used once file pages.  Reclaiming
MADV_FREE pages will not have much interfere of anonymous and active
file pages.  And the inactive file pages and MADV_FREE pages will be
reclaimed according to their age, so we don't reclaim too many MADV_FREE
pages too.  Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also
means we can reclaim the pages without swap support.  This idea is
suggested by Johannes.

This patch doesn't move MADV_FREE pages to LRU_INACTIVE_FILE list yet to
avoid bisect failure, next patch will do it.

The patch is based on Minchan's original patch.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/2f87063c1e9354677b7618c647abde77b07561e5.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: don't assume anonymous pages have SwapBacked flag

There are a few places the code assumes anonymous pages should have
SwapBacked flag set.  MADV_FREE pages are anonymous pages but we are
going to add them to LRU_INACTIVE_FILE list and clear SwapBacked flag
for them.  The assumption doesn't hold any more, so fix them.

Link: http://lkml.kernel.org/r/3945232c0df3dd6c4ef001976f35a95f18dcb407.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: delete unnecessary TTU_* flags

Patch series "mm: fix some MADV_FREE issues", v5.

We are trying to use MADV_FREE in jemalloc.  Several issues are found.
Without solving the issues, jemalloc can't use the MADV_FREE feature.

 - Doesn't support system without swap enabled. Because if swap is off,
   we can't or can't efficiently age anonymous pages. And since
   MADV_FREE pages are mixed with other anonymous pages, we can't
   reclaim MADV_FREE pages. In current implementation, MADV_FREE will
   fallback to MADV_DONTNEED without swap enabled. But in our
   environment, a lot of machines don't enable swap. This will prevent
   our setup using MADV_FREE.

 - Increases memory pressure. page reclaim bias file pages reclaim
   against anonymous pages. This doesn't make sense for MADV_FREE pages,
   because those pages could be freed easily and refilled with very
   slight penality. Even page reclaim doesn't bias file pages, there is
   still an issue, because MADV_FREE pages and other anonymous pages are
   mixed together. To reclaim a MADV_FREE page, we probably must scan a
   lot of other anonymous pages, which is inefficient. In our test, we
   usually see oom with MADV_FREE enabled and nothing without it.

 - Accounting. There are two accounting problems. We don't have a global
   accounting. If the system is abnormal, we don't know if it's a
   problem from MADV_FREE side. The other problem is RSS accounting.
   MADV_FREE pages are accounted as normal anon pages and reclaimed
   lazily, so application's RSS becomes bigger. This confuses our
   workloads. We have monitoring daemon running and if it finds
   applications' RSS becomes abnormal, the daemon will kill the
   applications even kernel can reclaim the memory easily.

To address the first the two issues, we can either put MADV_FREE pages
into a separate LRU list (Minchan's previous patches and V1 patches), or
put them into LRU_INACTIVE_FILE list (suggested by Johannes).  The
patchset use the second idea.  The reason is LRU_INACTIVE_FILE list is
tiny nowadays and should be full of used once file pages.  So we can
still efficiently reclaim MADV_FREE pages there without interference
with other anon and active file pages.  Putting the pages into inactive
file list also has an advantage which allows page reclaim to prioritize
MADV_FREE pages and used once file pages.  MADV_FREE pages are put into
the lru list and clear SwapBacked flag, so PageAnon(page) &&
!PageSwapBacked(page) will indicate a MADV_FREE pages.  These pages will
directly freed without pageout if they are clean, otherwise normal swap
will reclaim them.

For the third issue, the previous post adds global accounting and a
separate RSS count for MADV_FREE pages.  The problem is we never get
accurate accounting for MADV_FREE pages.  The pages are mapped to
userspace, can be dirtied without notice from kernel side.  To get
accurate accounting, we could write protect the page, but then there is
extra page fault overhead, which people don't want to pay.  Jemalloc
guys have concerns about the inaccurate accounting, so this post drops
the accounting patches temporarily.  The info exported to
/proc/pid/smaps for MADV_FREE pages are kept, which is the only place we
can get accurate accounting right now.

This patch (of 6):

Johannes pointed out TTU_LZFREE is unnecessary.  It's true because we
always have the flag set if we want to do an unmap.  For cases we don't
do an unmap, the TTU_LZFREE part of code should never run.

Also the TTU_UNMAP is unnecessary.  If no other flags set (for example,
TTU_MIGRATION), an unmap is implied.

The patch includes Johannes's cleanup and dead TTU_ACTION macro removal
code

Link: http://lkml.kernel.org/r/4be3ea1bc56b26fd98a54d0a6f70bec63f6d8980.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page-writeback.c: use setup_deferrable_timer

Use setup_deferrable_timer() instead of init_timer_deferrable() to
simplify the code.

Link: http://lkml.kernel.org/r/e8e3d4280a34facbc007346f31df833cec28801e.1488070291.git.geliangtang@gmail.com
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove unnecessary back-off function when retrying page reclaim

The backoff mechanism is not needed.  If we have MAX_RECLAIM_RETRIES
loops without progress, we'll OOM anyway; backing off might cut one or
two iterations off that in the rare OOM case.  If we have intermittent
success reclaiming a few pages, the backoff function gets reset also,
and so is of little help in these scenarios.

We might want a backoff function for when there IS progress, but not
enough to be satisfactory.  But this isn't that.  Remove it.

Link: http://lkml.kernel.org/r/20170228214007.5621-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Revert "mm, vmscan: account for skipped pages as a partial scan"

This reverts commit d7f05528eedb047efe2288cff777676b028747b6.

Now that reclaimability of a node is no longer based on the ratio
between pages scanned and theoretically reclaimable pages, we can remove
accounting tricks for pages skipped due to zone constraints.

Link: http://lkml.kernel.org/r/20170228214007.5621-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: delete NR_PAGES_SCANNED and pgdat_reclaimable()

NR_PAGES_SCANNED counts number of pages scanned since the last page free
event in the allocator.  This was used primarily to measure the
reclaimability of zones and nodes, and determine when reclaim should
give up on them.  In that role, it has been replaced in the preceding
patches by a different mechanism.

Being implemented as an efficient vmstat counter, it was automatically
exported to userspace as well.  It's however unlikely that anyone
outside the kernel is using this counter in any meaningful way.

Remove the counter and the unused pgdat_reclaimable().

Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: don't avoid high-priority reclaim on memcg limit reclaim

Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets")
sought to avoid high reclaim priorities for memcg by forcing it to scan
a minimum amount of pages when lru_pages >> priority yielded nothing.
This was done at a time when reclaim decisions like dirty throttling
were tied to the priority level.

Nowadays, the only meaningful thing still tied to priority dropping
below DEF_PRIORITY - 2 is gating whether laptop_mode=1 is generally
allowed to write.  But that is from an era where direct reclaim was
still allowed to call ->writepage, and kswapd nowadays avoids writes
until it's scanned every clean page in the system.  Potential changes to
how quick sc->may_writepage could trigger are of little concern.

Remove the force_scan stuff, as well as the ugly multi-pass target
calculation that it necessitated.

Link: http://lkml.kernel.org/r/20170228214007.5621-7-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: don't avoid high-priority reclaim on unreclaimable nodes

Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets")
sought to avoid high reclaim priorities for kswapd by forcing it to scan
a minimum amount of pages when lru_pages >> priority yielded nothing.

Commit b95a2f2d486d ("mm: vmscan: convert global reclaim to per-memcg
LRU lists"), due to switching global reclaim to a round-robin scheme
over all cgroups, had to restrict this forceful behavior to
unreclaimable zones in order to prevent massive overreclaim with many
cgroups.

The latter patch effectively neutered the behavior completely for all
but extreme memory pressure.  But in those situations we might as well
drop the reclaimers to lower priority levels.  Remove the check.

Link: http://lkml.kernel.org/r/20170228214007.5621-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove unnecessary reclaimability check from NUMA balancing target

NUMA balancing already checks the watermarks of the target node to
decide whether it's a suitable balancing target.  Whether the node is
reclaimable or not is irrelevant when we don't intend to reclaim.

Link: http://lkml.kernel.org/r/20170228214007.5621-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: remove seemingly spurious reclaimability check from laptop_mode gating

Commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of
nodes") allowed laptop_mode=1 to start writing not just when the
priority drops to DEF_PRIORITY - 2 but also when the node is
unreclaimable.

That appears to be a spurious change in this patch as I doubt the series
was tested with laptop_mode, and neither is that particular change
mentioned in the changelog.  Remove it, it's still recent.

Link: http://lkml.kernel.org/r/20170228214007.5621-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling

PF_MEMALLOC direct reclaimers get throttled on a node when the sum of
all free pages in each zone fall below half the min watermark.  During
the summation, we want to exclude zones that don't have reclaimables.
Checking the same pgdat over and over again doesn't make sense.

Fixes: 599d0c954f91 ("mm, vmscan: move LRU lists to node")
Link: http://lkml.kernel.org/r/20170228214007.5621-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: fix 100% CPU kswapd busyloop on unreclaimable nodes

Patch series "mm: kswapd spinning on unreclaimable nodes - fixes and
cleanups".

Jia reported a scenario in which the kswapd of a node indefinitely spins
at 100% CPU usage.  We have seen similar cases at Facebook.

The kernel's current method of judging its ability to reclaim a node (or
whether to back off and sleep) is based on the amount of scanned pages
in proportion to the amount of reclaimable pages.  In Jia's and our
scenarios, there are no reclaimable pages in the node, however, and the
condition for backing off is never met.  Kswapd busyloops in an attempt
to restore the watermarks while having nothing to work with.

This series reworks the definition of an unreclaimable node based not on
scanning but on whether kswapd is able to actually reclaim pages in
MAX_RECLAIM_RETRIES (16) consecutive runs.  This is the same criteria
the page allocator uses for giving up on direct reclaim and invoking the
OOM killer.  If it cannot free any pages, kswapd will go to sleep and
leave further attempts to direct reclaim invocations, which will either
make progress and re-enable kswapd, or invoke the OOM killer.

Patch #1 fixes the immediate problem Jia reported, the remainder are
smaller fixlets, cleanups, and overall phasing out of the old method.

Patch #6 is the odd one out.  It's a nice cleanup to get_scan_count(),
and directly related to #5, but in itself not relevant to the series.

If the whole series is too ambitious for 4.11, I would consider the
first three patches fixes, the rest cleanups.

This patch (of 9):

Jia He reports a problem with kswapd spinning at 100% CPU when
requesting more hugepages than memory available in the system:

$ echo 4000 >/proc/sys/vm/nr_hugepages

top - 13:42:59 up  3:37,  1 user,  load average: 1.09, 1.03, 1.01
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us, 12.5 sy,  0.0 ni, 85.5 id,  2.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:  31371520 total, 30915136 used,   456384 free,      320 buffers
KiB Swap:  6284224 total,   115712 used,  6168512 free.    48192 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
   76 root      20   0       0      0      0 R 100.0 0.000 217:17.29 kswapd3

At that time, there are no reclaimable pages left in the node, but as
kswapd fails to restore the high watermarks it refuses to go to sleep.

Kswapd needs to back away from nodes that fail to balance.  Up until
commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of
nodes") kswapd had such a mechanism.  It considered zones whose
theoretically reclaimable pages it had reclaimed six times over as
unreclaimable and backed away from them.  This guard was erroneously
removed as the patch changed the definition of a balanced node.

However, simply restoring this code wouldn't help in the case reported
here: there *are* no reclaimable pages that could be scanned until the
threshold is met.  Kswapd would stay awake anyway.

Introduce a new and much simpler way of backing off.  If kswapd runs
through MAX_RECLAIM_RETRIES (16) cycles without reclaiming a single
page, make it back off from the node.  This is the same number of shots
direct reclaim takes before declaring OOM.  Kswapd will go to sleep on
that node until a direct reclaimer manages to reclaim some pages, thus
proving the node reclaimable again.

[hannes@cmpxchg.org: check kswapd failure against the cumulative nr_reclaimed count]
Link: http://lkml.kernel.org/r/20170306162410.GB2090@cmpxchg.org
[shakeelb@google.com: fix condition for throttle_direct_reclaim]
Link: http://lkml.kernel.org/r/20170314183228.20152-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20170228214007.5621-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Jia He <hejianet@gmail.com>
Tested-by: Jia He <hejianet@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

slab: avoid IPIs when creating kmem caches

Each slab kmem cache has per cpu array caches.  The array caches are
created when the kmem_cache is created, either via kmem_cache_create()
or lazily when the first object is allocated in context of a kmem
enabled memcg.  Array caches are replaced by writing to /proc/slabinfo.

Array caches are protected by holding slab_mutex or disabling
interrupts.  Array cache allocation and replacement is done by
__do_tune_cpucache() which holds slab_mutex and calls
kick_all_cpus_sync() to interrupt all remote processors which confirms
there are no references to the old array caches.

IPIs are needed when replacing array caches.  But when creating a new
array cache, there's no need to send IPIs because there cannot be any
references to the new cache.  Outside of memcg kmem accounting these
IPIs occur at boot time, so they're not a problem.  But with memcg kmem
accounting each container can create kmem caches, so the IPIs are
wasteful.

Avoid unnecessary IPIs when creating array caches.

Test which reports the IPI count of allocating slab in 10000 memcg:

import os

def ipi_count():
with open("/proc/interrupts") as f:
for l in f:
if 'Function call interrupts' in l:
return int(l.split()[1])

def echo(val, path):
with open(path, "w") as f:
f.write(val)

n = 10000
os.chdir("/mnt/cgroup/memory")
pid = str(os.getpid())
a = ipi_count()
for i in range(n):
os.mkdir(str(i))
echo("1G\n", "%d/memory.limit_in_bytes" % i)
echo("1G\n", "%d/memory.kmem.limit_in_bytes" % i)
echo(pid, "%d/cgroup.procs" % i)
open("/tmp/x", "w").close()
os.unlink("/tmp/x")
b = ipi_count()
print "%d loops: %d => %d (+%d ipis)" % (n, a, b, b-a)
echo(pid, "cgroup.procs")
for i in range(n):
os.rmdir(str(i))

patched:   10000 loops: 1069 => 1170 (+101 ipis)
unpatched: 10000 loops: 1192 => 48933 (+47741 ipis)

Link: http://lkml.kernel.org/r/20170416214544.109476-1-gthelen@google.com
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>