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vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure 

Greg Thelen reported recent Johannes's stack diet patch makes kernel hang.
 His test is following.

  mount -t cgroup none /cgroups -o memory
  mkdir /cgroups/cg1
  echo $$ > /cgroups/cg1/tasks
  dd bs=1024 count=1024 if=/dev/null of=/data/foo
  echo $$ > /cgroups/tasks
  echo 1 > /cgroups/cg1/memory.force_empty

Actually, This OOM hard to try logic have been corrupted since following
two years old patch.

	commit a41f24ea9f
	Author: Nishanth Aravamudan <nacc@us.ibm.com>
	Date:   Tue Apr 29 00:58:25 2008 -0700

	    page allocator: smarter retry of costly-order allocations

Original intention was "return success if the system have shrinkable zones
though priority==0 reclaim was failure".  But the above patch changed to
"return nr_reclaimed if .....".  Oh, That forgot nr_reclaimed may be 0 if
priority==0 reclaim failure.

And Johannes's patch 0aeb2339e5 ("vmscan: remove all_unreclaimable scan
control") made it more corrupt.  Originally, priority==0 reclaim failure
on memcg return 0, but this patch changed to return 1.  It totally
confused memcg.

This patch fixes it completely.

Reported-by: Greg Thelen <gthelen@google.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: Greg Thelen <gthelen@google.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro 2010-06-04 14:15:05 -07:00 committed by Linus Torvalds
parent 9e506f7adc
commit bb21c7ce18
1 changed files with 16 additions and 13 deletions
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29
mm/vmscan.c
View File

@ -1724,13 +1724,13 @@ 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 int shrink_zones(int priority, struct zonelist *zonelist,
static bool shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc)
{
enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
struct zoneref *z;
struct zone *zone;
int progress = 0;
bool all_unreclaimable = true;
for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
sc->nodemask) {
@ -1757,9 +1757,9 @@ static int shrink_zones(int priority, struct zonelist *zonelist,
}
shrink_zone(priority, zone, sc);
progress = 1;
all_unreclaimable = false;
}
return progress;
return all_unreclaimable;
}
/*
@ -1782,7 +1782,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
struct scan_control *sc)
{
int priority;
unsigned long ret = 0;
bool all_unreclaimable;
unsigned long total_scanned = 0;
struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long lru_pages = 0;
@ -1813,7 +1813,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
sc->nr_scanned = 0;
if (!priority)
disable_swap_token();
ret = shrink_zones(priority, zonelist, sc);
all_unreclaimable = shrink_zones(priority, zonelist, sc);
/*
* Don't shrink slabs when reclaiming memory from
* over limit cgroups
@ -1826,10 +1826,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
}
}
total_scanned += sc->nr_scanned;
if (sc->nr_reclaimed >= sc->nr_to_reclaim) {
ret = sc->nr_reclaimed;
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
goto out;
}
/*
* Try to write back as many pages as we just scanned. This
@ -1849,9 +1847,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
priority < DEF_PRIORITY - 2)
congestion_wait(BLK_RW_ASYNC, HZ/10);
}
/* top priority shrink_zones still had more to do? don't OOM, then */
if (ret && scanning_global_lru(sc))
ret = sc->nr_reclaimed;
out:
/*
* Now that we've scanned all the zones at this priority level, note
@ -1877,7 +1873,14 @@ out:
delayacct_freepages_end();
put_mems_allowed();
return ret;
if (sc->nr_reclaimed)
return sc->nr_reclaimed;
/* top priority shrink_zones still had more to do? don't OOM, then */
if (scanning_global_lru(sc) && !all_unreclaimable)
return 1;
return 0;
}
unsigned long try_to_free_pages(struct zonelist *zonelist, int order,