path: root/mm
diff options
authorMichal Hocko <mhocko@suse.cz>2015-03-12 16:25:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-03-12 18:46:07 -0700
commite009d5dc0a94a7133e5f1c083732d760bfd038e6 (patch)
tree844948083016ecb8fe5f7b346c5bada45f34defd /mm
parentdrivers/rtc/rtc-s3c.c: add .needs_src_clk to s3c6410 RTC data (diff)
mm, oom: do not fail __GFP_NOFAIL allocation if oom killer is disabled
Tetsuo Handa has pointed out that __GFP_NOFAIL allocations might fail after OOM killer is disabled if the allocation is performed by a kernel thread. This behavior was introduced from the very beginning by 7f33d49a2ed5 ("mm, PM/Freezer: Disable OOM killer when tasks are frozen"). This means that the basic contract for the allocation request is broken and the context requesting such an allocation might blow up unexpectedly. There are basically two ways forward. 1) move oom_killer_disable after kernel threads are frozen. This has a risk that the OOM victim wouldn't be able to finish because it would depend on an already frozen kernel thread. This would be really tricky to debug. 2) do not fail GFP_NOFAIL allocation no matter what and risk a potential Freezable kernel threads will loop and fail the suspend. Incidental allocations after kernel threads are frozen will at least dump a warning - if we are lucky and the serial console is still active of course... This patch implements the later option because it is safer. We would see warning rather than allocation failures for the kernel threads which would blow up otherwise and have a higher chances to identify __GFP_NOFAIL users from deeper pm code. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: David Rientjes <rientjes@gooogle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7abfa70cdc1a..40e29429e7b0 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2373,7 +2373,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
goto out;
/* Exhausted what can be done so it's blamo time */
- if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false))
+ if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false)
+ || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
*did_some_progress = 1;
oom_zonelist_unlock(ac->zonelist, gfp_mask);