On Fri 08-07-16 01:06:12, Tetsuo Handa wrote:
> >From 2da51204250a2f1127792f98c12436771c07b67d Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Date: Fri, 8 Jul 2016 00:41:38 +0900
> Subject: [PATCH 5/6] mm,oom: Remove OOM_SCAN_ABORT case and signal_struct->oom_victims.
>
> Since oom_has_pending_mm() controls whether to select next OOM victim,
> we no longer need to abort OOM victim selection loop using OOM_SCAN_ABORT
> case. Also, since signal_struct->oom_victims was used only for allowing
> oom_scan_process_thread() to return OOM_SCAN_ABORT, we no longer need to
> use signal_struct->oom_victims.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Yes this looks good!
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> include/linux/oom.h | 1 -
> include/linux/sched.h | 1 -
> mm/memcontrol.c | 8 --------
> mm/oom_kill.c | 26 +-------------------------
> 4 files changed, 1 insertion(+), 35 deletions(-)
>
> diff --git a/include/linux/oom.h b/include/linux/oom.h
> index cb3f041..27be4ba 100644
> --- a/include/linux/oom.h
> +++ b/include/linux/oom.h
> @@ -49,7 +49,6 @@ enum oom_constraint {
> enum oom_scan_t {
> OOM_SCAN_OK, /* scan thread and find its badness */
> OOM_SCAN_CONTINUE, /* do not consider thread for oom kill */
> - OOM_SCAN_ABORT, /* abort the iteration and return */
> OOM_SCAN_SELECT, /* always select this thread first */
> };
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index c0efd80..2f57cf1c 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -670,7 +670,6 @@ struct signal_struct {
> atomic_t sigcnt;
> atomic_t live;
> int nr_threads;
> - atomic_t oom_victims; /* # of TIF_MEDIE threads in this thread group */
> struct list_head thread_head;
>
> wait_queue_head_t wait_chldexit; /* for wait4() */
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5043324..6afe1c5 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1262,14 +1262,6 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
> /* fall through */
> case OOM_SCAN_CONTINUE:
> continue;
> - case OOM_SCAN_ABORT:
> - css_task_iter_end(&it);
> - mem_cgroup_iter_break(memcg, iter);
> - if (chosen)
> - put_task_struct(chosen);
> - /* Set a dummy value to return "true". */
> - chosen = (void *) 1;
> - goto unlock;
> case OOM_SCAN_OK:
> break;
> };
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 223e1fe..b6b79ae 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -304,25 +304,6 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
> return OOM_SCAN_CONTINUE;
>
> /*
> - * This task already has access to memory reserves and is being killed.
> - * Don't allow any other task to have access to the reserves unless
> - * the task has MMF_OOM_REAPED because chances that it would release
> - * any memory is quite low.
> - */
> - if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) {
> - struct task_struct *p = find_lock_task_mm(task);
> - enum oom_scan_t ret = OOM_SCAN_ABORT;
> -
> - if (p) {
> - if (test_bit(MMF_OOM_REAPED, &p->mm->flags))
> - ret = OOM_SCAN_CONTINUE;
> - task_unlock(p);
> - }
> -
> - return ret;
> - }
> -
> - /*
> * If task is allocating a lot of memory and has been marked to be
> * killed first if it triggers an oom, then select it.
> */
> @@ -354,9 +335,6 @@ static struct task_struct *select_bad_process(struct oom_control *oc,
> /* fall through */
> case OOM_SCAN_CONTINUE:
> continue;
> - case OOM_SCAN_ABORT:
> - rcu_read_unlock();
> - return (struct task_struct *)(-1UL);
> case OOM_SCAN_OK:
> break;
> };
> @@ -626,7 +604,6 @@ void mark_oom_victim(struct task_struct *tsk)
> /* OOM killer might race with memcg OOM */
> if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
> return;
> - atomic_inc(&tsk->signal->oom_victims);
> /*
> * Make sure that the task is woken up from uninterruptible sleep
> * if it is frozen because OOM killer wouldn't be able to free
> @@ -659,7 +636,6 @@ void exit_oom_victim(struct task_struct *tsk)
> {
> if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
> return;
> - atomic_dec(&tsk->signal->oom_victims);
>
> if (!atomic_dec_return(&oom_victims))
> wake_up_all(&oom_victims_wait);
> @@ -1012,7 +988,7 @@ bool out_of_memory(struct oom_control *oc)
> dump_header(oc, NULL);
> panic("Out of memory and no killable processes...\n");
> }
> - if (p && p != (void *)-1UL) {
> + if (p) {
> oom_kill_process(oc, p, points, totalpages, "Out of memory");
> /*
> * Give the killed process a good chance to exit before trying
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
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