mm/memblock: debug: don't free reserved array if !ARCH_DISCARD_MEMBLOCK

Now the Nobootmem allocator will always try to free memory allocated for
reserved memory regions (free_low_memory_core_early()) without taking
into to account current memblock debugging configuration
(CONFIG_ARCH_DISCARD_MEMBLOCK and CONFIG_DEBUG_FS state).

As result if:

 - CONFIG_DEBUG_FS defined
 - CONFIG_ARCH_DISCARD_MEMBLOCK not defined;
 - reserved memory regions array have been resized during boot

then:

 - memory allocated for reserved memory regions array will be freed to
   buddy allocator;
 - debug_fs entry "sys/kernel/debug/memblock/reserved" will show garbage
   instead of state of memory reservations.  like:
   0: 0x98393bc0..0x9a393bbf
   1: 0xff120000..0xff11ffff
   2: 0x00000000..0xffffffff

Hence, do not free memory allocated for reserved memory regions if
defined(CONFIG_DEBUG_FS) && !defined(CONFIG_ARCH_DISCARD_MEMBLOCK).

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memblock.c b/mm/memblock.c
index 6a2a48a122a91928561677f7b66b329aab0dc201..de4d9c352fd64dfd8a072db1504c6b3bbd9bbf15 100644 (file)
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -269,6 +269,19 @@ phys_addr_t __init_memblock get_allocated_memblock_reserved_regions_info(
        if (memblock.reserved.regions == memblock_reserved_init_regions)
                return 0;
 
+       /*
+        * Don't allow nobootmem allocator to free reserved memory regions
+        * array if
+        *  - CONFIG_DEBUG_FS is enabled;
+        *  - CONFIG_ARCH_DISCARD_MEMBLOCK is not enabled;
+        *  - reserved memory regions array have been resized during boot.
+        * Otherwise debug_fs entry "sys/kernel/debug/memblock/reserved"
+        * will show garbage instead of state of memory reservations.
+        */
+       if (IS_ENABLED(CONFIG_DEBUG_FS) &&
+           !IS_ENABLED(CONFIG_ARCH_DISCARD_MEMBLOCK))
+               return 0;
+
        *addr = __pa(memblock.reserved.regions);
 
        return PAGE_ALIGN(sizeof(struct memblock_region) *