On Sunday, September 12, 2010, Minchan Kim wrote: > Adnrew, Please drop my old version and merge this verstion. > (old : vmscan-check-all_unreclaimable-in-direct-reclaim-path.patch) > > * Changelog from v2 > * remove inline - suggested by Andrew > * add function desription - suggeseted by Adnrew > > == CUT HERE == For the record, this commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6715045ddc7472a22be5e49d4047d2d89b391f45 is reported to fix the problem without the $subject patch (see http://lkml.org/lkml/2010/9/11/129). So, I'm not sure if it's still necessary to special case this particular situation? Thanks, Rafael > Subject: [PATCH v2] vmscan: check all_unreclaimable in direct reclaim path > > M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his > 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771) > Also he was bisected first bad commit is below > > commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c > Author: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Date: Fri Jun 4 14:15:05 2010 -0700 > > vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure > > At first impression, this seemed very strange because the above commit only > chenged function return value and hibernate_preallocate_memory() ignore > return value of shrink_all_memory(). But it's related. > > Now, page allocation from hibernation code may enter infinite loop if > the system has highmem. The reasons are that vmscan don't care enough > OOM case when oom_killer_disabled. > > The problem sequence is following as. > > 1. hibernation > 2. oom_disable > 3. alloc_pages > 4. do_try_to_free_pages > if (scanning_global_lru(sc) && !all_unreclaimable) > return 1; > > If kswapd is not freezed, it would set zone->all_unreclaimable to 1 and then > shrink_zones maybe return true(ie, all_unreclaimable is true). > so at last, alloc_pages could go to _nopage_. If it is, it should have no problem. > > This patch adds all_unreclaimable check to protect in direct reclaim path, too. > It can care of hibernation OOM case and help bailout all_unreclaimable case slightly. > > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: M. Vefa Bicakci <bicave@xxxxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxx > Acked-by: Rafael J. Wysocki <rjw@xxxxxxx> > Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > --- > mm/vmscan.c | 46 ++++++++++++++++++++++++++++++++++++++-------- > 1 files changed, 38 insertions(+), 8 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7870893..ecae0ef 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1877,12 +1877,11 @@ static void shrink_zone(int priority, struct zone *zone, > * If a zone is deemed to be full of pinned pages then just give it a light > * scan then give up on it. > */ > -static bool shrink_zones(int priority, struct zonelist *zonelist, > +static void shrink_zones(int priority, struct zonelist *zonelist, > struct scan_control *sc) > { > struct zoneref *z; > struct zone *zone; > - bool all_unreclaimable = true; > > for_each_zone_zonelist_nodemask(zone, z, zonelist, > gfp_zone(sc->gfp_mask), sc->nodemask) { > @@ -1900,8 +1899,41 @@ static bool shrink_zones(int priority, struct zonelist *zonelist, > } > > shrink_zone(priority, zone, sc); > - all_unreclaimable = false; > } > +} > + > +static bool zone_reclaimable(struct zone *zone) > +{ > + return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; > +} > + > +/* > + * As hibernation is going on, kswapd is freezed so that it can't mark > + * the zone into all_unreclaimable. It can't handle OOM during hibernation. > + * So let's check zone's unreclaimable in direct reclaim as well as kswapd. > + */ > +static bool all_unreclaimable(struct zonelist *zonelist, > + struct scan_control *sc) > +{ > + struct zoneref *z; > + struct zone *zone; > + bool all_unreclaimable = true; > + > + if (!scanning_global_lru(sc)) > + return false; > + > + for_each_zone_zonelist_nodemask(zone, z, zonelist, > + gfp_zone(sc->gfp_mask), sc->nodemask) { > + if (!populated_zone(zone)) > + continue; > + if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) > + continue; > + if (zone_reclaimable(zone)) { > + all_unreclaimable = false; > + break; > + } > + } > + > return all_unreclaimable; > } > > @@ -1925,7 +1957,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > struct scan_control *sc) > { > int priority; > - bool all_unreclaimable; > unsigned long total_scanned = 0; > struct reclaim_state *reclaim_state = current->reclaim_state; > struct zoneref *z; > @@ -1942,7 +1973,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > sc->nr_scanned = 0; > if (!priority) > disable_swap_token(); > - all_unreclaimable = shrink_zones(priority, zonelist, sc); > + shrink_zones(priority, zonelist, sc); > /* > * Don't shrink slabs when reclaiming memory from > * over limit cgroups > @@ -2004,7 +2035,7 @@ out: > return sc->nr_reclaimed; > > /* top priority shrink_zones still had more to do? don't OOM, then */ > - if (scanning_global_lru(sc) && !all_unreclaimable) > + if (!all_unreclaimable(zonelist, sc)) > return 1; > > return 0; > @@ -2270,8 +2301,7 @@ loop_again: > total_scanned += sc.nr_scanned; > if (zone->all_unreclaimable) > continue; > - if (nr_slab == 0 && > - zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) > + if (nr_slab == 0 && !zone_reclaimable(zone)) > zone->all_unreclaimable = 1; > /* > * If we've done a decent amount of scanning and > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . 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