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    Subject[PATCH 09/12] oom: remove PF_EXITING check completely
    Date
    Currently, PF_EXITING check is completely broken. because 1) It only
    care main-thread and ignore sub-threads 2) If user enable core-dump
    feature, it can makes deadlock because the task during coredump ignore
    SIGKILL.

    The deadlock is certenaly worst result, then, minor PF_EXITING
    optimization worth is relatively ignorable.

    This patch removes it.

    Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Acked-by: Oleg Nesterov <oleg@redhat.com>
    ---
    mm/oom_kill.c | 27 ---------------------------
    1 files changed, 0 insertions(+), 27 deletions(-)

    diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    index 6360c56..5d723fb 100644
    --- a/mm/oom_kill.c
    +++ b/mm/oom_kill.c
    @@ -302,24 +302,6 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
    if (test_tsk_thread_flag(p, TIF_MEMDIE))
    return ERR_PTR(-1UL);

    - /*
    - * This is in the process of releasing memory so wait for it
    - * to finish before killing some other task by mistake.
    - *
    - * However, if p is the current task, we allow the 'kill' to
    - * go ahead if it is exiting: this will simply set TIF_MEMDIE,
    - * which will allow it to gain access to memory reserves in
    - * the process of exiting and releasing its resources.
    - * Otherwise we could get an easy OOM deadlock.
    - */
    - if (p->flags & PF_EXITING) {
    - if (p != current)
    - return ERR_PTR(-1UL);
    -
    - chosen = p;
    - *ppoints = ULONG_MAX;
    - }
    -
    points = badness(p, uptime.tv_sec);
    if (points > *ppoints || !chosen) {
    chosen = p;
    @@ -444,15 +426,6 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
    if (printk_ratelimit())
    dump_header(p, gfp_mask, order, mem);

    - /*
    - * If the task is already exiting, don't alarm the sysadmin or kill
    - * its children or threads, just set TIF_MEMDIE so it can die quickly
    - */
    - if (p->flags & PF_EXITING) {
    - __oom_kill_process(p, mem, 0);
    - return 0;
    - }
    -
    printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
    message, task_pid_nr(p), p->comm, points);

    --
    1.6.5.2




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