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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 bisected
the regression to

  commit bb21c7ce18
  Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
  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 freozen, 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.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reported-by: M. Vefa Bicakci <bicave@superonline.com>
Reported-by: <caiqian@redhat.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: <caiqian@redhat.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2010-09-22 13:05:01 -07:00 committed by Linus Torvalds
parent eba93fcc34
commit d1908362ae
1 changed files with 35 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
mm/vmscan.c
View File

@ -1804,12 +1804,11 @@ 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) {
@ -1827,8 +1826,38 @@ 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;
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;
}
@ -1852,7 +1881,6 @@ 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;
@ -1869,7 +1897,7 @@ 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
@ -1931,7 +1959,7 @@ 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 (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))
return 1;
return 0;
@ -2197,8 +2225,7 @@ 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