Messages in this thread Patch in this message | | | Date | Tue, 3 May 2011 21:38:39 -0400 (EDT) | From | CAI Qian <> | Subject | Re: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable() |
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----- Original Message ----- > On 03/05/2011 06:20 PM, Minchan Kim wrote: > > On Sat, Mar 05, 2011 at 02:44:16PM +0300, Andrey Vagin wrote: > >> Check zone->all_unreclaimable in all_unreclaimable(), otherwise the > >> kernel may hang up, because shrink_zones() will do nothing, but > >> all_unreclaimable() will say, that zone has reclaimable pages. > >> > >> do_try_to_free_pages() > >> shrink_zones() > >> for_each_zone > >> if (zone->all_unreclaimable) > >> continue > >> if !all_unreclaimable(zonelist, sc) > >> return 1 > >> > >> __alloc_pages_slowpath() > >> retry: > >> did_some_progress = do_try_to_free_pages(page) > >> ... > >> if (!page&& did_some_progress) > >> retry; > >> > >> Signed-off-by: Andrey Vagin<avagin@openvz.org> > >> --- > >> mm/vmscan.c | 2 ++ > >> 1 files changed, 2 insertions(+), 0 deletions(-) > >> > >> diff --git a/mm/vmscan.c b/mm/vmscan.c > >> index 6771ea7..1c056f7 100644 > >> --- a/mm/vmscan.c > >> +++ b/mm/vmscan.c > >> @@ -2002,6 +2002,8 @@ static bool all_unreclaimable(struct zonelist > >> *zonelist, > >> > >> for_each_zone_zonelist_nodemask(zone, z, zonelist, > >> gfp_zone(sc->gfp_mask), sc->nodemask) { > >> + if (zone->all_unreclaimable) > >> + continue; > >> if (!populated_zone(zone)) > >> continue; > >> if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) > > > > zone_reclaimable checks it. Isn't it enough? > I sent one more patch [PATCH] mm: skip zombie in OOM-killer. > This two patches are enough. > > Does the hang up really happen or see it by code review? > Yes. You can reproduce it for help the attached python program. It's > not > very clever:) > It make the following actions in loop: > 1. fork > 2. mmap > 3. touch memory > 4. read memory > 5. munmmap > > >> -- > >> 1.7.1 I have tested this for the latest mainline kernel using the reproducer attached, the system just hung or deadlock after oom. The whole oom trace is here. http://people.redhat.com/qcai/oom.log
Did I miss anything?import sys, time, mmap, os from subprocess import Popen, PIPE import random
global mem_size
def info(msg): pid = os.getpid() print >> sys.stderr, "%s: %s" % (pid, msg) sys.stderr.flush()
def memory_loop(cmd = "a"): """ cmd may be: c: check memory else: touch memory """ c = 0 for j in xrange(0, mem_size): if cmd == "c": if f[j<<12] != chr(j % 255): info("Data corruption") sys.exit(1) else: f[j<<12] = chr(j % 255)
while True: pid = os.fork() if (pid != 0): mem_size = random.randint(0, 56 * 4096) f = mmap.mmap(-1, mem_size << 12, mmap.MAP_ANONYMOUS|mmap.MAP_PRIVATE) memory_loop() memory_loop("c") f.close()
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