From 0f7896f12b6a3dae3ffccbebe8c954d954350f3d Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 3 May 2017 14:55:34 -0700 Subject: [PATCH] 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 Acked-by: Michal Hocko Cc: Stanislaw Gruszka Cc: Mel Gorman Cc: Andrea Arcangeli Cc: "Rafael J . Wysocki" Cc: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f1f225608413..1e2af704938d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3092,8 +3092,7 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...) static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); - if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || - debug_guardpage_minorder() > 0) + if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs)) return; pr_warn("%s: ", current->comm); -- 2.20.1