From: Michal Hocko <mhocko@kernel.org> To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: linux-mm@kvack.org, rientjes@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, oleg@redhat.com Subject: Re: [PATCH 2/3] oom, oom_reaper: Try to reap tasks which skip regular OOM killer path Date: Fri, 8 Apr 2016 13:50:33 +0200 [thread overview] Message-ID: <20160408115033.GH29820@dhcp22.suse.cz> (raw) In-Reply-To: <201604082019.EDH52671.OJHQFMStOFLVOF@I-love.SAKURA.ne.jp> On Fri 08-04-16 20:19:28, Tetsuo Handa wrote: > Tetsuo Handa wrote: > > Michal Hocko wrote: > > > @@ -694,6 +746,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, > > > task_lock(p); > > > if (p->mm && task_will_free_mem(p)) { > > > mark_oom_victim(p); > > > + try_oom_reaper(p); > > > task_unlock(p); > > > put_task_struct(p); > > > return; > > > @@ -873,6 +926,7 @@ bool out_of_memory(struct oom_control *oc) > > > if (current->mm && > > > (fatal_signal_pending(current) || task_will_free_mem(current))) { > > > mark_oom_victim(current); > > > + try_oom_reaper(current); > > > return true; > > > } > > > > > oom_reaper() will need to do "tsk->oom_reaper_list = NULL;" due to > > if (tsk == oom_reaper_list || tsk->oom_reaper_list) > return; > > test in wake_oom_reaper() if "[PATCH 3/3] mm, oom_reaper: clear > TIF_MEMDIE for all tasks queued for oom_reaper" will select the same > thread again. true, will update my patch. > Though I think we should not allow the OOM killer to select the same > thread again. > > > > > Why don't you call try_oom_reaper() from the shortcuts in > > mem_cgroup_out_of_memory() as well? > > I looked at next-20160408 but I again came to think that we should remove > these shortcuts (something like a patch shown bottom). feel free to send the patch with the full description. But I would really encourage you to check the history to learn why those have been added and describe why those concerns are not valid/important anymore. Your way of throwing a large patch based on an extreme load which is basically DoSing the machine is not the ideal one. I do respect your different opinion. It is well possible that you are right here and you can convince all the reviewers that your changes are safe. I would be more than happy to drop my smaller steps approach then. But I will be honest with you, you haven't convinced me yet and I have seen so many subtle issues in this code area that the risk is really non trivial for any larger changes. This is the primary reason I am doing small steps each focusing on a single improvement which can be argued about and is known to help a particular case without introducing a risk of different problems. I am not the maintainer so it is not up to me to select the right approach. -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: linux-mm@kvack.org, rientjes@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, oleg@redhat.com Subject: Re: [PATCH 2/3] oom, oom_reaper: Try to reap tasks which skip regular OOM killer path Date: Fri, 8 Apr 2016 13:50:33 +0200 [thread overview] Message-ID: <20160408115033.GH29820@dhcp22.suse.cz> (raw) In-Reply-To: <201604082019.EDH52671.OJHQFMStOFLVOF@I-love.SAKURA.ne.jp> On Fri 08-04-16 20:19:28, Tetsuo Handa wrote: > Tetsuo Handa wrote: > > Michal Hocko wrote: > > > @@ -694,6 +746,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, > > > task_lock(p); > > > if (p->mm && task_will_free_mem(p)) { > > > mark_oom_victim(p); > > > + try_oom_reaper(p); > > > task_unlock(p); > > > put_task_struct(p); > > > return; > > > @@ -873,6 +926,7 @@ bool out_of_memory(struct oom_control *oc) > > > if (current->mm && > > > (fatal_signal_pending(current) || task_will_free_mem(current))) { > > > mark_oom_victim(current); > > > + try_oom_reaper(current); > > > return true; > > > } > > > > > oom_reaper() will need to do "tsk->oom_reaper_list = NULL;" due to > > if (tsk == oom_reaper_list || tsk->oom_reaper_list) > return; > > test in wake_oom_reaper() if "[PATCH 3/3] mm, oom_reaper: clear > TIF_MEMDIE for all tasks queued for oom_reaper" will select the same > thread again. true, will update my patch. > Though I think we should not allow the OOM killer to select the same > thread again. > > > > > Why don't you call try_oom_reaper() from the shortcuts in > > mem_cgroup_out_of_memory() as well? > > I looked at next-20160408 but I again came to think that we should remove > these shortcuts (something like a patch shown bottom). feel free to send the patch with the full description. But I would really encourage you to check the history to learn why those have been added and describe why those concerns are not valid/important anymore. Your way of throwing a large patch based on an extreme load which is basically DoSing the machine is not the ideal one. I do respect your different opinion. It is well possible that you are right here and you can convince all the reviewers that your changes are safe. I would be more than happy to drop my smaller steps approach then. But I will be honest with you, you haven't convinced me yet and I have seen so many subtle issues in this code area that the risk is really non trivial for any larger changes. This is the primary reason I am doing small steps each focusing on a single improvement which can be argued about and is known to help a particular case without introducing a risk of different problems. I am not the maintainer so it is not up to me to select the right approach. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-04-08 11:50 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-06 14:13 [PATCH 0/3] oom reaper follow ups v1 Michal Hocko 2016-04-06 14:13 ` Michal Hocko 2016-04-06 14:13 ` [PATCH 1/3] mm, oom: move GFP_NOFS check to out_of_memory Michal Hocko 2016-04-06 14:13 ` Michal Hocko 2016-04-06 14:13 ` [PATCH 2/3] oom, oom_reaper: Try to reap tasks which skip regular OOM killer path Michal Hocko 2016-04-06 14:13 ` Michal Hocko 2016-04-07 11:38 ` Tetsuo Handa 2016-04-07 11:38 ` Tetsuo Handa 2016-04-08 11:19 ` Tetsuo Handa 2016-04-08 11:19 ` Tetsuo Handa 2016-04-08 11:50 ` Michal Hocko [this message] 2016-04-08 11:50 ` Michal Hocko 2016-04-09 4:39 ` [PATCH 2/3] oom, oom_reaper: Try to reap tasks which skipregular " Tetsuo Handa 2016-04-09 4:39 ` Tetsuo Handa 2016-04-11 12:02 ` Michal Hocko 2016-04-11 12:02 ` Michal Hocko 2016-04-11 13:26 ` [PATCH 2/3] oom, oom_reaper: Try to reap tasks which skip regular " Tetsuo Handa 2016-04-11 13:26 ` Tetsuo Handa 2016-04-11 13:43 ` Michal Hocko 2016-04-11 13:43 ` Michal Hocko 2016-04-13 11:08 ` Tetsuo Handa 2016-04-13 11:08 ` Tetsuo Handa 2016-04-08 11:34 ` Michal Hocko 2016-04-08 11:34 ` Michal Hocko 2016-04-08 13:14 ` Michal Hocko 2016-04-08 13:14 ` Michal Hocko 2016-04-06 14:13 ` [PATCH 3/3] mm, oom_reaper: clear TIF_MEMDIE for all tasks queued for oom_reaper Michal Hocko 2016-04-06 14:13 ` Michal Hocko 2016-04-07 11:55 ` Tetsuo Handa 2016-04-07 11:55 ` Tetsuo Handa 2016-04-08 11:34 ` Michal Hocko 2016-04-08 11:34 ` Michal Hocko 2016-04-16 2:51 ` Tetsuo Handa 2016-04-17 11:54 ` Michal Hocko 2016-04-18 11:59 ` Tetsuo Handa 2016-04-19 14:17 ` Michal Hocko 2016-04-19 15:07 ` Tetsuo Handa 2016-04-19 19:32 ` Michal Hocko 2016-04-08 13:07 ` Michal Hocko 2016-04-08 13:07 ` Michal Hocko
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20160408115033.GH29820@dhcp22.suse.cz \ --to=mhocko@kernel.org \ --cc=akpm@linux-foundation.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=oleg@redhat.com \ --cc=penguin-kernel@I-love.SAKURA.ne.jp \ --cc=rientjes@google.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.