Michal Hocko wrote: > From: Michal Hocko <[email protected]> > > Currently we do warn only about allocation failures but small > allocations are basically nofail and they might loop in the page > allocator for a long time. Especially when the reclaim cannot make > any progress - e.g. GFP_NOFS cannot invoke the oom killer and rely on > a different context to make a forward progress in case there is a lot > memory used by filesystems. > > Give us at least a clue when something like this happens and warn about > allocations which take more than 10s. Print the basic allocation context > information along with the cumulative time spent in the allocation as > well as the allocation stack. Repeat the warning after every 10 seconds so > that we know that the problem is permanent rather than ephemeral. > > Signed-off-by: Michal Hocko <[email protected]> > --- > mm/page_alloc.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 969ffc97045b..73f60ad6315f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3495,6 +3495,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int > order, > enum compact_result compact_result; > int compaction_retries = 0; > int no_progress_loops = 0; > + unsigned long alloc_start = jiffies; > + unsigned int stall_timeout = 10 * HZ; > > /* > * In the slowpath, we sanity check order to avoid ever trying to > @@ -3650,6 +3652,14 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int > order, > if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_REPEAT)) > goto nopage; > > + /* Make sure we know about allocations which stall for too long */ > + if (time_after(jiffies, alloc_start + stall_timeout)) { > + warn_alloc(gfp_mask,
I expect "gfp_mask & ~__GFP_NOWARN" rather than "gfp_mask" here. Otherwise, we can't get a clue for __GFP_NOWARN allocations. > + "page alloction stalls for %ums, order:%u\n", > + jiffies_to_msecs(jiffies-alloc_start), order); > + stall_timeout += 10 * HZ; > + } > + > if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, > did_some_progress > 0, &no_progress_loops)) > goto retry; > -- > 2.9.3
