On 2020/07/16 2:30, David Rientjes wrote:
> But regardless of whether we present previous data to the user in the
> kernel log or not, we've determined that oom killing a process is a
> serious matter and go to any lengths possible to avoid having to do it.
> For us, that means waiting until the "point of no return" to either go
> ahead with oom killing a process or aborting and retrying the charge.
>
> I don't think moving the mem_cgroup_margin() check to out_of_memory()
> right before printing the oom info and killing the process is a very
> invasive patch. Any strong preference against doing it that way? I think
> moving the check as late as possible to save a process from being killed
> when racing with an exiter or killed process (including perhaps current)
> has a pretty clear motivation.
>
How about ignoring MMF_OOM_SKIP for once? I think this has almost same
effect as moving the mem_cgroup_margin() check to out_of_memory()
right before printing the oom info and killing the process.
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 48e0db54d838..88170af3b9eb 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -322,7 +322,8 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
* any memory is quite low.
*/
if (!is_sysrq_oom(oc) && tsk_is_oom_victim(task)) {
- if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags))
+ if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags) &&
+ !test_and_clear_bit(MMF_OOM_REAP_QUEUED, &task->signal->oom_mm->flags))
goto next;
goto abort;
}
@@ -658,7 +659,8 @@ static int oom_reaper(void *unused)
static void wake_oom_reaper(struct task_struct *tsk)
{
/* mm is already queued? */
- if (test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags))
+ if (test_bit(MMF_OOM_SKIP, &tsk->signal->oom_mm->flags) ||
+ test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags))
return;
get_task_struct(tsk);
