Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933136AbbLRAPY (ORCPT ); Thu, 17 Dec 2015 19:15:24 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:52752 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932140AbbLRAPX (ORCPT ); Thu, 17 Dec 2015 19:15:23 -0500 Date: Thu, 17 Dec 2015 16:15:21 -0800 From: Andrew Morton To: Michal Hocko Cc: Mel Gorman , Tetsuo Handa , David Rientjes , Linus Torvalds , Oleg Nesterov , Hugh Dickins , Andrea Argangeli , Rik van Riel , , LKML , Michal Hocko Subject: Re: [PATCH 1/2] mm, oom: introduce oom reaper Message-Id: <20151217161521.57fb536085aca377cb93fe1e@linux-foundation.org> In-Reply-To: <1450204575-13052-1-git-send-email-mhocko@kernel.org> References: <1450204575-13052-1-git-send-email-mhocko@kernel.org> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3392 Lines: 119 On Tue, 15 Dec 2015 19:36:15 +0100 Michal Hocko wrote: > This patch reduces the probability of such a lockup by introducing a > specialized kernel thread (oom_reaper) CONFIG_MMU=n: slub.c:(.text+0x4184): undefined reference to `tlb_gather_mmu' slub.c:(.text+0x41bc): undefined reference to `unmap_page_range' slub.c:(.text+0x41d8): undefined reference to `tlb_finish_mmu' I did the below so I can get an mmotm out the door, but hopefully there's a cleaner way. --- a/mm/oom_kill.c~mm-oom-introduce-oom-reaper-fix-3 +++ a/mm/oom_kill.c @@ -415,6 +415,7 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_victi bool oom_killer_disabled __read_mostly; +#ifdef CONFIG_MMU /* * OOM Reaper kernel thread which tries to reap the memory used by the OOM * victim (if that is possible) to help the OOM killer to move on. @@ -517,6 +518,27 @@ static void wake_oom_reaper(struct mm_st mmdrop(mm); } +static int __init oom_init(void) +{ + oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper"); + if (IS_ERR(oom_reaper_th)) { + pr_err("Unable to start OOM reaper %ld. Continuing regardless\n", + PTR_ERR(oom_reaper_th)); + oom_reaper_th = NULL; + } else { + struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; + + /* + * Make sure our oom reaper thread will get scheduled when + * ASAP and that it won't get preempted by malicious userspace. + */ + sched_setscheduler(oom_reaper_th, SCHED_FIFO, ¶m); + } + return 0; +} +module_init(oom_init) +#endif + /** * mark_oom_victim - mark the given task as OOM victim * @tsk: task to mark @@ -626,7 +648,9 @@ void oom_kill_process(struct oom_control unsigned int victim_points = 0; static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); +#ifdef CONFIG_MMU bool can_oom_reap = true; +#endif /* * If the task is already exiting, don't alarm the sysadmin or kill @@ -719,6 +743,7 @@ void oom_kill_process(struct oom_control continue; if (is_global_init(p)) continue; +#ifdef CONFIG_MMU if (unlikely(p->flags & PF_KTHREAD) || p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { /* @@ -729,13 +754,16 @@ void oom_kill_process(struct oom_control can_oom_reap = false; continue; } - +#endif do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); } rcu_read_unlock(); +#ifdef CONFIG_MMU if (can_oom_reap) wake_oom_reaper(mm); +#endif + mmdrop(mm); put_task_struct(victim); } @@ -887,23 +915,3 @@ void pagefault_out_of_memory(void) mutex_unlock(&oom_lock); } - -static int __init oom_init(void) -{ - oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper"); - if (IS_ERR(oom_reaper_th)) { - pr_err("Unable to start OOM reaper %ld. Continuing regardless\n", - PTR_ERR(oom_reaper_th)); - oom_reaper_th = NULL; - } else { - struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; - - /* - * Make sure our oom reaper thread will get scheduled when - * ASAP and that it won't get preempted by malicious userspace. - */ - sched_setscheduler(oom_reaper_th, SCHED_FIFO, ¶m); - } - return 0; -} -module_init(oom_init) _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/