Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check should take ->mm into account

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From: David Rientjes

Subject: Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check should take ->mm into account

Date: Tuesday, June 1, 2010 - 1:39 pm

On Mon, 31 May 2010, KOSAKI Motohiro wrote:

quoted text> From: Oleg Nesterov <oleg@redhat.com>
> Subject: oom: select_bad_process: PF_EXITING check should take ->mm into account
> 
> select_bad_process() checks PF_EXITING to detect the task which is going
> to release its memory, but the logic is very wrong.
> 
> 	- a single process P with the dead group leader disables
> 	  select_bad_process() completely, it will always return
> 	  ERR_PTR() while P can live forever
> 
> 	- if the PF_EXITING task has already released its ->mm
> 	  it doesn't make sense to expect it is goiing to free
> 	  more memory (except task_struct/etc)
> 
> Change the code to ignore the PF_EXITING tasks without ->mm.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Acked-by: David Rientjes <rientjes@google.com>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [rebase to latest -mm]

This is already pushed in my oom killer rewrite as patch 13/18 "oom: avoid 
race for oom killed tasks detaching mm prior to exit".

It's not vital to merge now because causing the oom killer to temporarily 
become a no-op before it can fully exit even though it has already 
detached its memory only delays killing another task until it exits and 
there's nothing in the way of that exiting while it's still under 
PF_EXITING.
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Messages in current thread:

[PATCH 1/5] oom: select_bad_process: check PF_KTHREAD inst ..., KOSAKI Motohiro, (Mon May 31, 2:33 am)

[PATCH 2/5] oom: select_bad_process: PF_EXITING check shou ..., KOSAKI Motohiro, (Mon May 31, 2:35 am)

[PATCH 3/5] oom: introduce find_lock_task_mm() to fix !mm ..., KOSAKI Motohiro, (Mon May 31, 2:36 am)

[PATCH 4/5] oom: the points calculation of child processes ..., KOSAKI Motohiro, (Mon May 31, 2:37 am)

[PATCH 5/5] oom: __oom_kill_task() must use find_lock_task ..., KOSAKI Motohiro, (Mon May 31, 2:38 am)

Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check ..., Oleg Nesterov, (Mon May 31, 9:43 am)

Re: [PATCH 4/5] oom: the points calculation of child proce ..., Oleg Nesterov, (Mon May 31, 9:56 am)

Re: [PATCH 4/5] oom: the points calculation of child proce ..., KOSAKI Motohiro, (Mon May 31, 4:48 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., KAMEZAWA Hiroyuki, (Mon May 31, 5:54 pm)

Re: [PATCH 3/5] oom: introduce find_lock_task_mm() to fix ..., KAMEZAWA Hiroyuki, (Mon May 31, 5:57 pm)

Re: [PATCH 5/5] oom: __oom_kill_task() must use find_lock_ ..., KAMEZAWA Hiroyuki, (Mon May 31, 6:02 pm)

Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check ..., KOSAKI Motohiro, (Mon May 31, 6:10 pm)

Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check ..., Oleg Nesterov, (Tue Jun 1, 1:18 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., David Rientjes, (Tue Jun 1, 1:36 pm)

Re: [PATCH 2/5] oom: select_bad_process: PF_EXITING check ..., David Rientjes, (Tue Jun 1, 1:39 pm)

Re: [PATCH 3/5] oom: introduce find_lock_task_mm() to fix ..., David Rientjes, (Tue Jun 1, 1:42 pm)

Re: [PATCH 5/5] oom: __oom_kill_task() must use find_lock_ ..., David Rientjes, (Tue Jun 1, 1:44 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., Oleg Nesterov, (Tue Jun 1, 2:20 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., David Rientjes, (Tue Jun 1, 2:26 pm)

[PATCH] oom: remove PF_EXITING check completely, KOSAKI Motohiro, (Wed Jun 2, 6:54 am)

[PATCH] oom: Make coredump interruptible, KOSAKI Motohiro, (Wed Jun 2, 6:54 am)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., KOSAKI Motohiro, (Wed Jun 2, 6:54 am)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., Minchan Kim, (Wed Jun 2, 8:32 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Wed Jun 2, 8:42 am)

Re: [PATCH] oom: remove PF_EXITING check completely, Oleg Nesterov, (Wed Jun 2, 8:54 am)

Re: [PATCH 3/5] oom: introduce find_lock_task_mm() to fix ..., Minchan Kim, (Wed Jun 2, 9:05 am)

Re: [PATCH] oom: Make coredump interruptible, Roland McGrath, (Wed Jun 2, 10:29 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Wed Jun 2, 10:53 am)

Re: [PATCH] oom: Make coredump interruptible, Roland McGrath, (Wed Jun 2, 11:58 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Wed Jun 2, 1:38 pm)

Re: [PATCH] oom: remove PF_EXITING check completely, David Rientjes, (Wed Jun 2, 2:02 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., David Rientjes, (Wed Jun 2, 2:09 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., Oleg Nesterov, (Wed Jun 2, 2:33 pm)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., David Rientjes, (Wed Jun 2, 2:46 pm)

Re: [PATCH] oom: remove PF_EXITING check completely, KOSAKI Motohiro, (Wed Jun 2, 9:48 pm)

Re: [PATCH] oom: remove PF_EXITING check completely, David Rientjes, (Wed Jun 2, 11:29 pm)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Thu Jun 3, 7:03 am)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., Oleg Nesterov, (Thu Jun 3, 7:27 am)

Re: [PATCH 1/5] oom: select_bad_process: check PF_KTHREAD ..., David Rientjes, (Thu Jun 3, 1:11 pm)

Re: [PATCH] oom: Make coredump interruptible, KOSAKI Motohiro, (Fri Jun 4, 3:54 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Fri Jun 4, 4:27 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Fri Jun 4, 4:34 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Wed Jun 9, 12:53 pm)

Re: [PATCH] oom: Make coredump interruptible, David Rientjes, (Wed Jun 9, 1:41 pm)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Wed Jun 9, 2:03 pm)

Re: [PATCH] oom: Make coredump interruptible, KOSAKI Motohiro, (Sun Jun 13, 4:24 am)

Re: [PATCH] oom: Make coredump interruptible, Oleg Nesterov, (Sun Jun 13, 8:53 am)

uninterruptible CLONE_VFORK (Was: oom: Make coredump inter ..., Oleg Nesterov, (Sun Jun 13, 10:13 am)

Re: [PATCH] oom: Make coredump interruptible, Roland McGrath, (Sun Jun 13, 5:26 pm)

Re: [PATCH] oom: Make coredump interruptible, Roland McGrath, (Sun Jun 13, 5:36 pm)

Re: uninterruptible CLONE_VFORK (Was: oom: Make coredump i ..., Roland McGrath, (Sun Jun 13, 5:56 pm)

Re: uninterruptible CLONE_VFORK (Was: oom: Make coredump i ..., Oleg Nesterov, (Mon Jun 14, 9:33 am)

Re: uninterruptible CLONE_VFORK (Was: oom: Make coredump i ..., Roland McGrath, (Mon Jun 14, 12:17 pm)

Re: uninterruptible CLONE_VFORK (Was: oom: Make coredump i ..., Oleg Nesterov, (Mon Jun 28, 10:33 am)

Re: uninterruptible CLONE_VFORK (Was: oom: Make coredump i ..., Roland McGrath, (Mon Jun 28, 11:04 am)