Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 20 Aug 2020 16:04:52 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/1] mm, oom_adj: don't loop through tasks in __set_oom_adj when not necessary |
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On 08/20, Eric W. Biederman wrote: > > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1139,6 +1139,10 @@ static int exec_mmap(struct mm_struct *mm) > vmacache_flush(tsk); > task_unlock(tsk); > if (old_mm) { > + mm->oom_score_adj = old_mm->oom_score_adj; > + mm->oom_score_adj_min = old_mm->oom_score_adj_min; > + if (tsk->vfork_done) > + mm->oom_score_adj = tsk->vfork_oom_score_adj;
too late, ->vfork_done is NULL after mm_release().
And this can race with __set_oom_adj(). Yes, the current code is racy too, but this change adds another race, __set_oom_adj() could already observe ->mm != NULL and update mm->oom_score_adj.
Oleg.
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