Commit 1be334e5 authored Nov 05, 2019 by Johannes Weiner Committed by Linus Torvalds Nov 06, 2019

mm/page_alloc.c: ratelimit allocation failure warnings more aggressively

While investigating a bug related to higher atomic allocation failures,
we noticed the failure warnings positively drowning the console, and in
our case trigger lockup warnings because of a serial console too slow to
handle all that output.

But even if we had a faster console, it's unclear what additional
information the current level of repetition provides.

Allocation failures happen for three reasons: The machine is OOM, the VM
is failing to handle reasonable requests, or somebody is making
unreasonable requests (and didn't acknowledge their opportunism with
__GFP_NOWARN).  Having the memory dump, a callstack, and the ratelimit
stats on skipped failure warnings should provide enough information to
let users/admins/developers know whether something is wrong and point
them in the right direction for debugging, bpftracing etc.

Limit allocation failure warnings to one spew every ten seconds.

Link: http://lkml.kernel.org/r/20191028194906.26899-1-hannes@cmpxchg.org


Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ec649c9d

mm/page_alloc.c

+1 −6

Original line number	Diff line number	Diff line
		@@ -3728,10 +3728,6 @@ try_this_zone:
		static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask)
		{
		unsigned int filter = SHOW_MEM_FILTER_NODES;
		static DEFINE_RATELIMIT_STATE(show_mem_rs, HZ, 1);

		if (!__ratelimit(&show_mem_rs))
		return;

		/*
		* This documents exceptions given to allocations in certain
		@@ -3752,8 +3748,7 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t nodemask, const char fmt, ...)
		{
		struct va_format vaf;
		va_list args;
		static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL,
		DEFAULT_RATELIMIT_BURST);
		static DEFINE_RATELIMIT_STATE(nopage_rs, 10*HZ, 1);

		if ((gfp_mask & __GFP_NOWARN) \|\| !__ratelimit(&nopage_rs))
		return;

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