On Sun, Sep 05, 2010 at 11:40:37PM +0900, Minchan Kim wrote: > 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: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rjw@xxxxxxx> > Cc: M. Vefa Bicakci <bicave@xxxxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxx > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> > --- > mm/vmscan.c | 33 +++++++++++++++++++++++++++------ > 1 files changed, 27 insertions(+), 6 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index f620ab3..53b23a7 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1893,12 +1893,11 @@ 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) { > @@ -1916,8 +1915,31 @@ static bool shrink_zones(int priority, struct zonelist *zonelist, > } > > shrink_zone(priority, zone, sc); > - all_unreclaimable = false; > } > +} > + > +static inline 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->pages_scanned < (zone_reclaimable_pages(zone) * 6)) { Small nitpick: kswapd does the same check against the magic number, could you move it into a separate function? zone_reclaimable()? Otherwise, Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx> > + all_unreclaimable = false; > + break; > + } > + } > + > return all_unreclaimable; > } > > @@ -1941,7 +1963,6 @@ 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; > @@ -1958,7 +1979,7 @@ 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 > @@ -2020,7 +2041,7 @@ 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; > -- > 1.7.0.5 > > -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>