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    Subject[BUGFIX][PATCH] vmscan: don't use return value trick when oom_killer_disabled
    Date
    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@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 two. 1) hibernate_preallocate_memory() call
    alloc_pages() wrong order 2) vmscan don't care enough OOM case when
    oom_killer_disabled.

    This patch only fix (2). Why is oom_killer_disabled so special?
    because when hibernation case, zone->all_unreclaimable never be turned on.
    hibernation freeze all tasks at first, then kswapd can't works in this
    case, and zone->all_unreclaimable is only turned from kswapd.

    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    Cc: M. Vefa Bicakci <bicave@superonline.com>
    Cc: stable@kernel.org
    Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    ---
    mm/vmscan.c | 3 ++-
    1 files changed, 2 insertions(+), 1 deletions(-)

    diff --git a/mm/vmscan.c b/mm/vmscan.c
    index c391c32..1919d8a 100644
    --- a/mm/vmscan.c
    +++ b/mm/vmscan.c
    @@ -40,6 +40,7 @@
    #include <linux/memcontrol.h>
    #include <linux/delayacct.h>
    #include <linux/sysctl.h>
    +#include <linux/oom.h>

    #include <asm/tlbflush.h>
    #include <asm/div64.h>
    @@ -1931,7 +1932,7 @@ 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 && !oom_killer_disabled)
    return 1;

    return 0;
    --
    1.6.5.2




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