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>

diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index 49d7c997fa1ee7f759b5ba319bb57be464f0bd47..e50b95c25868f15f101e97176a8665391b9e71da 100644 (file)
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -871,6 +871,11 @@ PAGE_SIZE multiple when read back.
 
                Amount of memory used in network transmission buffers
 
+         shmem
+
+               Amount of cached filesystem data that is swap-backed,
+               such as tmpfs, shm segments, shared anonymous mmap()s
+
          file_mapped
 
                Amount of cached filesystem data mapped with mmap()

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index bb7250c45cb8356b03df2d4b9f1325dc6e30069b..c5ebb32fef49cd1521720e5f71dcfe5a3f40ee50 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -46,6 +46,7 @@ enum mem_cgroup_stat_index {
        MEM_CGROUP_STAT_CACHE,          /* # of pages charged as cache */
        MEM_CGROUP_STAT_RSS,            /* # of pages charged as anon rss */
        MEM_CGROUP_STAT_RSS_HUGE,       /* # of pages charged as anon huge */
+       MEM_CGROUP_STAT_SHMEM,          /* # of pages charged as shmem */
        MEM_CGROUP_STAT_FILE_MAPPED,    /* # of pages charged as file rss */
        MEM_CGROUP_STAT_DIRTY,          /* # of dirty pages in page cache */
        MEM_CGROUP_STAT_WRITEBACK,      /* # of pages under writeback */

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2bd7541d7c11231431c060ca6cfe84a89f096fe3..490d5b4676c1a09b204d76d652f41802afa298c7 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -104,6 +104,7 @@ static const char * const mem_cgroup_stat_names[] = {
        "cache",
        "rss",
        "rss_huge",
+       "shmem",
        "mapped_file",
        "dirty",
        "writeback",
@@ -608,9 +609,13 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
        if (PageAnon(page))
                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
                                nr_pages);
-       else
+       else {
                __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
                                nr_pages);
+               if (PageSwapBacked(page))
+                       __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SHMEM],
+                                      nr_pages);
+       }
 
        if (compound) {
                VM_BUG_ON_PAGE(!PageTransHuge(page), page);
@@ -5208,6 +5213,8 @@ static int memory_stat_show(struct seq_file *m, void *v)
        seq_printf(m, "sock %llu\n",
                   (u64)stat[MEMCG_SOCK] * PAGE_SIZE);
 
+       seq_printf(m, "shmem %llu\n",
+                  (u64)stat[MEM_CGROUP_STAT_SHMEM] * PAGE_SIZE);
        seq_printf(m, "file_mapped %llu\n",
                   (u64)stat[MEM_CGROUP_STAT_FILE_MAPPED] * PAGE_SIZE);
        seq_printf(m, "file_dirty %llu\n",
@@ -5476,8 +5483,8 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg,
 
 static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
                           unsigned long nr_anon, unsigned long nr_file,
-                          unsigned long nr_huge, unsigned long nr_kmem,
-                          struct page *dummy_page)
+                          unsigned long nr_kmem, unsigned long nr_huge,
+                          unsigned long nr_shmem, struct page *dummy_page)
 {
        unsigned long nr_pages = nr_anon + nr_file + nr_kmem;
        unsigned long flags;
@@ -5495,6 +5502,7 @@ static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
        __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS], nr_anon);
        __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_CACHE], nr_file);
        __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], nr_huge);
+       __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_SHMEM], nr_shmem);
        __this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT], pgpgout);
        __this_cpu_add(memcg->stat->nr_page_events, nr_pages);
        memcg_check_events(memcg, dummy_page);
@@ -5507,6 +5515,7 @@ static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
 static void uncharge_list(struct list_head *page_list)
 {
        struct mem_cgroup *memcg = NULL;
+       unsigned long nr_shmem = 0;
        unsigned long nr_anon = 0;
        unsigned long nr_file = 0;
        unsigned long nr_huge = 0;
@@ -5539,9 +5548,9 @@ static void uncharge_list(struct list_head *page_list)
                if (memcg != page->mem_cgroup) {
                        if (memcg) {
                                uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-                                              nr_huge, nr_kmem, page);
-                               pgpgout = nr_anon = nr_file =
-                                       nr_huge = nr_kmem = 0;
+                                              nr_kmem, nr_huge, nr_shmem, page);
+                               pgpgout = nr_anon = nr_file = nr_kmem = 0;
+                               nr_huge = nr_shmem = 0;
                        }
                        memcg = page->mem_cgroup;
                }
@@ -5555,8 +5564,11 @@ static void uncharge_list(struct list_head *page_list)
                        }
                        if (PageAnon(page))
                                nr_anon += nr_pages;
-                       else
+                       else {
                                nr_file += nr_pages;
+                               if (PageSwapBacked(page))
+                                       nr_shmem += nr_pages;
+                       }
                        pgpgout++;
                } else {
                        nr_kmem += 1 << compound_order(page);
@@ -5568,7 +5580,7 @@ static void uncharge_list(struct list_head *page_list)
 
        if (memcg)
                uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
-                              nr_huge, nr_kmem, page);
+                              nr_kmem, nr_huge, nr_shmem, page);
 }
 
 /**