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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>
This commit is contained in:
Johannes Weiner 2019-11-05 21:16:51 -08:00 committed by Linus Torvalds
parent ec649c9d45
commit 1be334e5c0
1 changed files with 1 additions and 6 deletions
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7
mm/page_alloc.c
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@ -3728,10 +3728,6 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
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;