On Wed, May 18, 2011 at 1:17 AM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > On Wed, May 18, 2011 at 4:22 AM, Andrew Lutomirski <luto@xxxxxxx> wrote: >>> No, thanks. However it would be valuable if you can retry with this >>> patch _alone_ (without the "if (need_resched()) return false;" change, >>> as I don't see how it helps your case). >>> >>> @@ -2286,7 +2290,7 @@ static bool sleeping_prematurely(pg_data_t >>> *pgdat, int order, long remaining, >>> * must be balanced >>> */ >>> if (order) >>> - return pgdat_balanced(pgdat, balanced, classzone_idx); >>> + return !pgdat_balanced(pgdat, balanced, classzone_idx); >>> else >>> return !all_zones_ok; >>> } >> >> Done. >> >> I logged in, added swap, and ran a program that allocated 1900MB of >> RAM and memset it. The system lagged a bit but survived. kswapd >> showed 10% CPU (which is odd, IMO, since I'm using aesni-intel and I >> think that all the crypt happens in kworker when aesni-intel is in >> use). > > I think kswapd could use 10% enough for reclaim. > >> >> Then I started Firefox, loaded gmail, and ran test_mempressure.sh. >> Kaboom! (I.e. system was hung) SysRq-F saved the system and produced > > Hang? > It means you see softhangup of kswapd? or mouse/keyboard doesn't move? Mouse and keyboard dead. > Andrew, Could you test this patch with !pgdat_balanced patch? > I think we shouldn't see OOM message if we have lots of free swap space. > > == CUT_HERE == > diff --git a/mm/vmscan.c b/mm/vmscan.c > index f73b865..cc23f04 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1341,10 +1341,6 @@ static inline bool > should_reclaim_stall(unsigned long nr_taken, > if (current_is_kswapd()) > return false; > > - /* Only stall on lumpy reclaim */ > - if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) > - return false; > - > /* If we have relaimed everything on the isolated list, no stall */ > if (nr_freed == nr_taken) > return false; > > > > Then, if you don't see any unnecessary OOM but still see the hangup, > could you apply this patch based on previous? With this patch, I started GNOME and Firefox, turned on swap, and ran test_mempressure.sh 1500 1400 1. Instant panic (or OOPS and hang or something -- didn't get the top part). Picture attached -- it looks like memcg might be involved. I'm running F15, so it might even be doing something. I won't be able to get netconsole dumps until next week because I'm out of town and only have this one computer here. I haven't tried the other patch. Also, the !pgdat_balanced fix plus the if (need_resched()) return false patch just hung once on 2.6.37-rc9. I don't know what triggered it. Maybe yum. --Andy
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