Re: [PATCH 6/5] oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: 2016-02-20 02:32:13
Also in:
lkml
Michal Hocko wrote:
On Wed 17-02-16 10:48:55, Michal Hocko wrote:quoted
Hi Andrew, although this can be folded into patch 5 (mm-oom_reaper-implement-oom-victims-queuing.patch) I think it would be better to have it separate and revert after we sort out the proper oom_kill_allocating_task behavior or handle exclusion at oom_reaper level.An alternative would be something like the following. It is definitely less hackish but it steals one bit in mm->flags. We do not seem to be in shortage there now but who knows. Does this sound better? Later changes might even consider the flag for the victim selection and ignore those which already have the flag set. But I didn't think about it more to form a patch yet.
This sounds better than "can_oom_reap = !sysctl_oom_kill_allocating_task;".
quoted hunk ↗ jump to hunk
@@ -740,6 +740,10 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, /* Get a reference to safely compare mm after task_unlock(victim) */ mm = victim->mm; atomic_inc(&mm->mm_count); + + /* Make sure we do not try to oom reap the mm multiple times */ + can_oom_reap = !test_and_set_bit(MMF_OOM_KILLED, &mm->flags); + /* * We should send SIGKILL before setting TIF_MEMDIE in order to prevent * the OOM victim from depleting the memory reserves from the user
But as of this line we don't know whether this mm is reapable.
Shouldn't this be done like
static void wake_oom_reaper(struct task_struct *tsk)
{
/* Make sure we do not try to oom reap the mm multiple times */
if (!oom_reaper_th || !test_and_set_bit(MMF_OOM_KILLED, &mm->flags))
return;
get_task_struct(tsk);
spin_lock(&oom_reaper_lock);
list_add(&tsk->oom_reaper_list, &oom_reaper_list);
spin_unlock(&oom_reaper_lock);
wake_up(&oom_reaper_wait);
}
?
Moreover, why don't you do like
struct mm_struct {
(...snipped...)
struct list_head oom_reaper_list;
(...snipped...)
}
than
struct task_struct {
(...snipped...)
struct list_head oom_reaper_list;
(...snipped...)
}
so that we can update all ->oom_score_adj using this mm_struct for handling
crazy combo ( http://lkml.kernel.org/r/20160204163113.GF14425@dhcp22.suse.cz ) ?
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