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[202.181.97.72]) by mx.google.com with ESMTPS id w198-v6si8520035oie.389.2018.06.07.04.01.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jun 2018 04:01:25 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) client-ip=202.181.97.72; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of penguin-kernel@i-love.sakura.ne.jp designates 202.181.97.72 as permitted sender) smtp.mailfrom=penguin-kernel@i-love.sakura.ne.jp Received: from fsav302.sakura.ne.jp (fsav302.sakura.ne.jp [153.120.85.133]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w57B0V0L033501; Thu, 7 Jun 2018 20:00:31 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav302.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav302.sakura.ne.jp); Thu, 07 Jun 2018 20:00:31 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav302.sakura.ne.jp) Received: from ccsecurity.localdomain (softbank126074194044.bbtec.net [126.74.194.44]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w57B0OPA033466 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 7 Jun 2018 20:00:30 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, Tetsuo Handa , David Rientjes , Johannes Weiner , Michal Hocko , Roman Gushchin , Tejun Heo , Vladimir Davydov Subject: [PATCH 4/4] mm, oom: Check pending victims earlier in out_of_memory(). Date: Thu, 7 Jun 2018 20:00:23 +0900 Message-Id: <1528369223-7571-4-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1528369223-7571-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> References: <1528369223-7571-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP The "mm, oom: cgroup-aware OOM killer" patchset is trying to introduce INFLIGHT_VICTIM in order to replace open-coded ((void *)-1UL). But (regarding CONFIG_MMU=y case) we have a list of inflight OOM victim threads which are connected to oom_reaper_list. Thus we can check whether there are inflight OOM victims before starting process/memcg list traversal. Since it is likely that only few threads are linked to oom_reaper_list, checking all victims' OOM domain will not matter. Thus, check whether there are inflight OOM victims before starting process/memcg list traversal and eliminate the "abort" path. Signed-off-by: Tetsuo Handa Cc: Roman Gushchin Cc: Michal Hocko Cc: Johannes Weiner Cc: Vladimir Davydov Cc: David Rientjes Cc: Tejun Heo --- include/linux/memcontrol.h | 9 ++--- mm/memcontrol.c | 18 +++------ mm/oom_kill.c | 99 +++++++++++++++++++++++++--------------------- 3 files changed, 64 insertions(+), 62 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index d99b71b..b9ee4f8 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -355,8 +355,8 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, struct mem_cgroup *, struct mem_cgroup_reclaim_cookie *); void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *); -int mem_cgroup_scan_tasks(struct mem_cgroup *, - int (*)(struct task_struct *, void *), void *); +void mem_cgroup_scan_tasks(struct mem_cgroup *memcg, + void (*fn)(struct task_struct *, void *), void *arg); static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) { @@ -806,10 +806,9 @@ static inline void mem_cgroup_iter_break(struct mem_cgroup *root, { } -static inline int mem_cgroup_scan_tasks(struct mem_cgroup *memcg, - int (*fn)(struct task_struct *, void *), void *arg) +static inline void mem_cgroup_scan_tasks(struct mem_cgroup *memcg, + void (*fn)(struct task_struct *, void *), void *arg) { - return 0; } static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1695f38..ba52fce 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -884,17 +884,14 @@ static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg) * @arg: argument passed to @fn * * This function iterates over tasks attached to @memcg or to any of its - * descendants and calls @fn for each task. If @fn returns a non-zero - * value, the function breaks the iteration loop and returns the value. - * Otherwise, it will iterate over all tasks and return 0. + * descendants and calls @fn for each task. * * This function must not be called for the root memory cgroup. */ -int mem_cgroup_scan_tasks(struct mem_cgroup *memcg, - int (*fn)(struct task_struct *, void *), void *arg) +void mem_cgroup_scan_tasks(struct mem_cgroup *memcg, + void (*fn)(struct task_struct *, void *), void *arg) { struct mem_cgroup *iter; - int ret = 0; BUG_ON(memcg == root_mem_cgroup); @@ -903,15 +900,10 @@ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg, struct task_struct *task; css_task_iter_start(&iter->css, 0, &it); - while (!ret && (task = css_task_iter_next(&it))) - ret = fn(task, arg); + while ((task = css_task_iter_next(&it))) + fn(task, arg); css_task_iter_end(&it); - if (ret) { - mem_cgroup_iter_break(memcg, iter); - break; - } } - return ret; } /** diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 5a6f1b1..0452a70 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -304,25 +304,13 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc) return CONSTRAINT_NONE; } -static int oom_evaluate_task(struct task_struct *task, void *arg) +static void oom_evaluate_task(struct task_struct *task, void *arg) { struct oom_control *oc = arg; unsigned long points; if (oom_unkillable_task(task, NULL, oc->nodemask)) - goto next; - - /* - * This task already has access to memory reserves and is being killed. - * Don't allow any other task to have access to the reserves unless - * the task has MMF_OOM_SKIP because chances that it would release - * any memory is quite low. - */ - if (!is_sysrq_oom(oc) && tsk_is_oom_victim(task)) { - if (test_bit(MMF_OOM_SKIP, &task->signal->oom_mm->flags)) - goto next; - goto abort; - } + return; /* * If task is allocating a lot of memory and has been marked to be @@ -335,29 +323,22 @@ static int oom_evaluate_task(struct task_struct *task, void *arg) points = oom_badness(task, NULL, oc->nodemask, oc->totalpages); if (!points || points < oc->chosen_points) - goto next; + return; /* Prefer thread group leaders for display purposes */ if (points == oc->chosen_points && thread_group_leader(oc->chosen)) - goto next; + return; select: if (oc->chosen) put_task_struct(oc->chosen); get_task_struct(task); oc->chosen = task; oc->chosen_points = points; -next: - return 0; -abort: - if (oc->chosen) - put_task_struct(oc->chosen); - oc->chosen = (void *)-1UL; - return 1; } /* * Simple selection loop. We choose the process with the highest number of - * 'points'. In case scan was aborted, oc->chosen is set to -1. + * 'points'. */ static void select_bad_process(struct oom_control *oc) { @@ -368,8 +349,7 @@ static void select_bad_process(struct oom_control *oc) rcu_read_lock(); for_each_process(p) - if (oom_evaluate_task(p, oc)) - break; + oom_evaluate_task(p, oc); rcu_read_unlock(); } @@ -476,7 +456,6 @@ bool process_shares_mm(struct task_struct *p, struct mm_struct *mm) */ static struct task_struct *oom_reaper_th; static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait); -static struct task_struct *oom_reaper_list; static DEFINE_SPINLOCK(oom_reaper_lock); /* @@ -606,14 +585,16 @@ static void oom_reap_task(struct task_struct *tsk) debug_show_all_locks(); done: - tsk->oom_reaper_list = NULL; - /* * Hide this mm from OOM killer because it has been either reaped or * somebody can't call up_write(mmap_sem). */ set_bit(MMF_OOM_SKIP, &mm->flags); + spin_lock(&oom_reaper_lock); + oom_reaper_th->oom_reaper_list = tsk->oom_reaper_list; + spin_unlock(&oom_reaper_lock); + /* Drop a reference taken by wake_oom_reaper */ put_task_struct(tsk); } @@ -621,14 +602,12 @@ static void oom_reap_task(struct task_struct *tsk) static int oom_reaper(void *unused) { while (true) { - struct task_struct *tsk = NULL; + struct task_struct *tsk; - wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL); + wait_event_freezable(oom_reaper_wait, + oom_reaper_th->oom_reaper_list != NULL); spin_lock(&oom_reaper_lock); - if (oom_reaper_list != NULL) { - tsk = oom_reaper_list; - oom_reaper_list = tsk->oom_reaper_list; - } + tsk = oom_reaper_th->oom_reaper_list; spin_unlock(&oom_reaper_lock); if (tsk) @@ -640,15 +619,18 @@ static int oom_reaper(void *unused) static void wake_oom_reaper(struct task_struct *tsk) { - /* tsk is already queued? */ - if (tsk == oom_reaper_list || tsk->oom_reaper_list) - return; - - get_task_struct(tsk); + struct task_struct *p = oom_reaper_th; spin_lock(&oom_reaper_lock); - tsk->oom_reaper_list = oom_reaper_list; - oom_reaper_list = tsk; + while (p != tsk && p->oom_reaper_list) + p = p->oom_reaper_list; + if (p == tsk) { + spin_unlock(&oom_reaper_lock); + return; + } + p->oom_reaper_list = tsk; + tsk->oom_reaper_list = NULL; + get_task_struct(tsk); spin_unlock(&oom_reaper_lock); trace_wake_reaper(tsk->pid); wake_up(&oom_reaper_wait); @@ -1010,6 +992,34 @@ int unregister_oom_notifier(struct notifier_block *nb) } EXPORT_SYMBOL_GPL(unregister_oom_notifier); +static bool oom_has_pending_victims(struct oom_control *oc) +{ +#ifdef CONFIG_MMU + struct task_struct *p; + + if (is_sysrq_oom(oc)) + return false; + /* + * Since oom_reap_task_mm()/exit_mmap() will set MMF_OOM_SKIP, let's + * wait for pending victims until MMF_OOM_SKIP is set. + */ + spin_lock(&oom_reaper_lock); + for (p = oom_reaper_th; p; p = p->oom_reaper_list) + if (!oom_unkillable_task(p, oc->memcg, oc->nodemask) && + !test_bit(MMF_OOM_SKIP, &p->signal->oom_mm->flags)) + break; + spin_unlock(&oom_reaper_lock); + return p != NULL; +#else + /* + * Since nobody except oom_kill_process() sets MMF_OOM_SKIP, waiting + * for pending victims until MMF_OOM_SKIP is set is useless. Therefore, + * simply let the OOM killer select pending victims again. + */ + return false; +#endif +} + /** * out_of_memory - kill the "best" process when we run out of memory * @oc: pointer to struct oom_control @@ -1063,6 +1073,9 @@ bool out_of_memory(struct oom_control *oc) oc->nodemask = NULL; check_panic_on_oom(oc, constraint); + if (oom_has_pending_victims(oc)) + return true; + if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task && current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) && current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) { @@ -1073,8 +1086,6 @@ bool out_of_memory(struct oom_control *oc) } select_bad_process(oc); - if (oc->chosen == (void *)-1UL) - return true; /* Found nothing?!?! Either we hang forever, or we panic. */ if (!oc->chosen) { if (is_sysrq_oom(oc) || is_memcg_oom(oc))