lkml.org 
[lkml]   [2010]   [Jun]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/5] oom: introduce find_lock_task_mm() to fix !mm false positives
    On Mon, 31 May 2010, KOSAKI Motohiro wrote:

    > From: Oleg Nesterov <oleg@redhat.com>
    > Subject: [PATCH 3/5] oom: introduce find_lock_task_mm() to fix !mm false positives
    >
    > Almost all ->mm == NUL checks in oom_kill.c are wrong.
    >
    > The current code assumes that the task without ->mm has already
    > released its memory and ignores the process. However this is not
    > necessarily true when this process is multithreaded, other live
    > sub-threads can use this ->mm.
    >
    > - Remove the "if (!p->mm)" check in select_bad_process(), it is
    > just wrong.
    >
    > - Add the new helper, find_lock_task_mm(), which finds the live
    > thread which uses the memory and takes task_lock() to pin ->mm
    >
    > - change oom_badness() to use this helper instead of just checking
    > ->mm != NULL.
    >
    > - As David pointed out, select_bad_process() must never choose the
    > task without ->mm, but no matter what badness() returns the
    > task can be chosen if nothing else has been found yet.
    >
    > Note! This patch is not enough, we need more changes.
    >
    > - badness() was fixed, but oom_kill_task() still ignores
    > the task without ->mm
    >
    > This will be addressed later.
    >
    > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    > Cc: David Rientjes <rientjes@google.com>
    > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [rebase
    > latest -mm and remove some obsoleted description]

    This is already pushed as part of my oom killer rewrite in patch 15/18
    "oom: introduce find_lock_task_mm to fix !mm false positives".


    \
     
     \ /
      Last update: 2010-06-01 22:45    [W:4.455 / U:0.380 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site