From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm: throttle show_mem() from warn_alloc() Tetsuo has been stressing OOM killer path with many parallel allocation requests when he has noticed that it is not all that hard to swamp kernel logs with warn_alloc messages caused by allocation stalls. Even though the allocation stall message is triggered only once in 10s there might be many different tasks hitting it roughly around the same time. A big part of the output is show_mem() which can generate a lot of output even on a small machines. There is no reason to show the state of memory counter for each allocation stall, especially when multiple of them are reported in a short time period. Chances are that not much has changed since the last report. This patch simply rate limits show_mem called from warn_alloc to only dump something once per second. This should be enough to give us a clue why an allocation might be stalling while burst of warnings will not swamp log with too much data. While we are at it, extract all the show_mem related handling (filters) into a separate function warn_alloc_show_mem. This will make the code cleaner and as a bonus point we can distinguish which part of warn_alloc got throttled due to rate limiting as ___ratelimit dumps the caller. [akpm@xxxxxxxxxxxxxxxxxxxx: reduce scope of the ratelimit_states] Link: http://lkml.kernel.org/r/20161215101510.9030-1-mhocko@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff -puN mm/page_alloc.c~mm-throttle-show_mem-from-warn_alloc mm/page_alloc.c --- a/mm/page_alloc.c~mm-throttle-show_mem-from-warn_alloc +++ a/mm/page_alloc.c @@ -3007,18 +3007,12 @@ static inline bool should_suppress_show_ return ret; } -static DEFINE_RATELIMIT_STATE(nopage_rs, - DEFAULT_RATELIMIT_INTERVAL, - DEFAULT_RATELIMIT_BURST); - -void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) +static void warn_alloc_show_mem(gfp_t gfp_mask) { unsigned int filter = SHOW_MEM_FILTER_NODES; - struct va_format vaf; - va_list args; + static DEFINE_RATELIMIT_STATE(show_mem_rs, HZ, 1); - if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || - debug_guardpage_minorder() > 0) + if (should_suppress_show_mem() || !__ratelimit(&show_mem_rs)) return; /* @@ -3033,6 +3027,20 @@ void warn_alloc(gfp_t gfp_mask, const ch if (in_interrupt() || !(gfp_mask & __GFP_DIRECT_RECLAIM)) filter &= ~SHOW_MEM_FILTER_NODES; + show_mem(filter); +} + +void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) +{ + struct va_format vaf; + va_list args; + static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + + if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || + debug_guardpage_minorder() > 0) + return; + pr_warn("%s: ", current->comm); va_start(args, fmt); @@ -3044,8 +3052,7 @@ void warn_alloc(gfp_t gfp_mask, const ch pr_cont(", mode:%#x(%pGg)\n", gfp_mask, &gfp_mask); dump_stack(); - if (!should_suppress_show_mem()) - show_mem(filter); + warn_alloc_show_mem(gfp_mask); } static inline struct page * _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
