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    SubjectRe: [patch -mm 2/9 v2] oom: sacrifice child with highest badness score for parent
    On Mon, Feb 15, 2010 at 02:20:03PM -0800, David Rientjes wrote:
    > When a task is chosen for oom kill, the oom killer first attempts to
    > sacrifice a child not sharing its parent's memory instead.
    > Unfortunately, this often kills in a seemingly random fashion based on
    > the ordering of the selected task's child list. Additionally, it is not
    > guaranteed at all to free a large amount of memory that we need to
    > prevent additional oom killing in the very near future.
    > Instead, we now only attempt to sacrifice the worst child not sharing its
    > parent's memory, if one exists. The worst child is indicated with the
    > highest badness() score. This serves two advantages: we kill a
    > memory-hogging task more often, and we allow the configurable
    > /proc/pid/oom_adj value to be considered as a factor in which child to
    > kill.
    > Reviewers may observe that the previous implementation would iterate
    > through the children and attempt to kill each until one was successful
    > and then the parent if none were found while the new code simply kills
    > the most memory-hogging task or the parent. Note that the only time
    > oom_kill_task() fails, however, is when a child does not have an mm or
    > has a /proc/pid/oom_adj of OOM_DISABLE. badness() returns 0 for both
    > cases, so the final oom_kill_task() will always succeed.
    > Acked-by: Rik van Riel <>
    > Reviewed-by: KAMEZAWA Hiroyuki <>
    > Reviewed-by: Minchan Kim <>
    > Reviewed-by: KOSAKI Motohiro <>
    > Signed-off-by: David Rientjes <>
    Acked-by: Nick Piggin <>

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