Messages in this thread | | | Subject | Re: [PATCH] mm: oom: Fix race condition between oom_badness and do_exit of task | From | "Kohli, Gaurav" <> | Date | Thu, 8 Mar 2018 10:21:26 +0530 |
| |
On 3/8/2018 2:26 AM, David Rientjes wrote:
> On Wed, 7 Mar 2018, Gaurav Kohli wrote: > >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c >> index 6fd9773..5f4cc4b 100644 >> --- a/mm/oom_kill.c >> +++ b/mm/oom_kill.c >> @@ -114,9 +114,11 @@ struct task_struct *find_lock_task_mm(struct task_struct *p) >> >> for_each_thread(p, t) { >> task_lock(t); >> + get_task_struct(t); >> if (likely(t->mm)) >> goto found; >> task_unlock(t); >> + put_task_struct(t); >> } >> t = NULL; >> found: > We hold rcu_read_lock() here, so perhaps only do get_task_struct() before > doing rcu_read_unlock() and we have a non-NULL t?
Here rcu_read_lock will not help, as our task may change due to below algo:
for_each_thread(p, t) { task_lock(t); + get_task_struct(t); if (likely(t->mm)) goto found; task_unlock(t); + put_task_struct(t)
So only we can increase usage counter here only at the current task.
I have seen you new patch, that seems valid to me and it will resolve our issue. Thanks for support.
Regards
Gaurav
> -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
| |