From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id 1651C6B025E for ; Thu, 7 Jul 2016 12:03:23 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id d132so38225863oig.0 for ; Thu, 07 Jul 2016 09:03:23 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id y198si2379868oia.31.2016.07.07.09.03.21 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 07 Jul 2016 09:03:22 -0700 (PDT) Subject: [PATCH 3/6] mm,oom: Use list of mm_struct used by OOM victims. From: Tetsuo Handa References: <201607080058.BFI87504.JtFOOFQFVHSLOM@I-love.SAKURA.ne.jp> In-Reply-To: <201607080058.BFI87504.JtFOOFQFVHSLOM@I-love.SAKURA.ne.jp> Message-Id: <201607080103.CDH12401.LFOHStQFOOFVJM@I-love.SAKURA.ne.jp> Date: Fri, 8 Jul 2016 01:03:11 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, oleg@redhat.com, rientjes@google.com, vdavydov@parallels.com, mst@redhat.com, mhocko@suse.com, mhocko@kernel.org >>From 5fbd16cffd5dc51f9ba8591fc18d315ff6ff9b96 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Fri, 8 Jul 2016 00:33:13 +0900 Subject: [PATCH 3/6] mm,oom: Use list of mm_struct used by OOM victims. Currently, we walk process list in order to find existing TIF_MEMDIE threads. But if we remember list of mm_struct used by TIF_MEMDIE threads, we can avoid walking process list. Next patch in this series allows OOM reaper to use list of mm_struct introduced by this patch. This patch reverts commit e2fe14564d3316d1 ("oom_reaper: close race with exiting task") because oom_has_pending_mm() will prevent that race. Since CONFIG_MMU=y kernel has OOM reaper callback hook which can remove mm_struct from the list, let the OOM reaper call exit_oom_mm(mm). This patch temporarily fails to call exit_oom_mm(mm) when find_lock_task_mm() in oom_reap_task() failed. It will be fixed by next patch. But since CONFIG_MMU=n kernel does not have OOM reaper callback hook, call exit_oom_mm(mm) from __mmput(mm) if that mm is used by OOM victims. Signed-off-by: Tetsuo Handa --- include/linux/mm_types.h | 7 +++++ include/linux/oom.h | 3 ++ kernel/fork.c | 4 +++ mm/memcontrol.c | 5 ++++ mm/oom_kill.c | 72 +++++++++++++++++++++++++++++++----------------- 5 files changed, 66 insertions(+), 25 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index e093e1d..7c1370a 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -392,6 +392,12 @@ struct mm_rss_stat { atomic_long_t count[NR_MM_COUNTERS]; }; +struct oom_mm { + struct list_head list; /* Linked to oom_mm_list list. */ + /* Thread which was passed to mark_oom_victim() for the last time. */ + struct task_struct *victim; +}; + struct kioctx_table; struct mm_struct { struct vm_area_struct *mmap; /* list of VMAs */ @@ -515,6 +521,7 @@ struct mm_struct { #ifdef CONFIG_HUGETLB_PAGE atomic_long_t hugetlb_usage; #endif + struct oom_mm oom_mm; #ifdef CONFIG_MMU struct work_struct async_put_work; #endif diff --git a/include/linux/oom.h b/include/linux/oom.h index 5bc0457..bdcb331 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -91,6 +91,9 @@ extern void oom_kill_process(struct oom_control *oc, struct task_struct *p, extern void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint); +extern void exit_oom_mm(struct mm_struct *mm); +extern bool oom_has_pending_mm(struct mem_cgroup *memcg, + const nodemask_t *nodemask); extern enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, struct task_struct *task); diff --git a/kernel/fork.c b/kernel/fork.c index 7926993..8e469e0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -722,6 +722,10 @@ static inline void __mmput(struct mm_struct *mm) } if (mm->binfmt) module_put(mm->binfmt->module); +#ifndef CONFIG_MMU + if (mm->oom_mm.victim) + exit_oom_mm(mm); +#endif mmdrop(mm); } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 40dfca3..8f7a5b7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1241,6 +1241,11 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, } check_panic_on_oom(&oc, CONSTRAINT_MEMCG); + if (oom_has_pending_mm(memcg, NULL)) { + /* Set a dummy value to return "true". */ + chosen = (void *) 1; + goto unlock; + } totalpages = mem_cgroup_get_limit(memcg) ? : 1; for_each_mem_cgroup_tree(iter, memcg) { struct css_task_iter it; diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 9f0022e..87e7ff3 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -275,6 +275,28 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc, } #endif +static LIST_HEAD(oom_mm_list); + +void exit_oom_mm(struct mm_struct *mm) +{ + mutex_lock(&oom_lock); + list_del(&mm->oom_mm.list); + put_task_struct(mm->oom_mm.victim); + mm->oom_mm.victim = NULL; + mmdrop(mm); + mutex_unlock(&oom_lock); +} + +bool oom_has_pending_mm(struct mem_cgroup *memcg, const nodemask_t *nodemask) +{ + struct mm_struct *mm; + + list_for_each_entry(mm, &oom_mm_list, oom_mm.list) + if (!oom_unkillable_task(mm->oom_mm.victim, memcg, nodemask)) + return true; + return false; +} + enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, struct task_struct *task) { @@ -458,28 +480,9 @@ static bool __oom_reap_task(struct task_struct *tsk, struct mm_struct *mm) struct vm_area_struct *vma; struct zap_details details = {.check_swap_entries = true, .ignore_dirty = true}; - bool ret = true; - /* - * We have to make sure to not race with the victim exit path - * and cause premature new oom victim selection: - * __oom_reap_task exit_mm - * mmget_not_zero - * mmput - * atomic_dec_and_test - * exit_oom_victim - * [...] - * out_of_memory - * select_bad_process - * # no TIF_MEMDIE task selects new victim - * unmap_page_range # frees some memory - */ - mutex_lock(&oom_lock); - - if (!down_read_trylock(&mm->mmap_sem)) { - ret = false; - goto unlock_oom; - } + if (!down_read_trylock(&mm->mmap_sem)) + return false; /* * increase mm_users only after we know we will reap something so @@ -488,7 +491,7 @@ static bool __oom_reap_task(struct task_struct *tsk, struct mm_struct *mm) */ if (!mmget_not_zero(mm)) { up_read(&mm->mmap_sem); - goto unlock_oom; + return true; } tlb_gather_mmu(&tlb, mm, 0, -1); @@ -536,9 +539,7 @@ static bool __oom_reap_task(struct task_struct *tsk, struct mm_struct *mm) * put the oom_reaper out of the way. */ mmput_async(mm); -unlock_oom: - mutex_unlock(&oom_lock); - return ret; + return true; } #define MAX_OOM_REAP_RETRIES 10 @@ -586,6 +587,9 @@ done: /* Drop a reference taken by wake_oom_reaper */ put_task_struct(tsk); + /* Drop references taken by mark_oom_victim() */ + if (mm) + exit_oom_mm(mm); /* Drop a reference taken above. */ if (mm) mmdrop(mm); @@ -653,6 +657,9 @@ subsys_initcall(oom_init) */ void mark_oom_victim(struct task_struct *tsk) { + struct mm_struct *mm = tsk->mm; + struct task_struct *old_tsk = mm->oom_mm.victim; + WARN_ON(oom_killer_disabled); /* OOM killer might race with memcg OOM */ if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE)) @@ -666,6 +673,18 @@ void mark_oom_victim(struct task_struct *tsk) */ __thaw_task(tsk); atomic_inc(&oom_victims); + /* + * Since mark_oom_victim() is called from multiple threads, + * connect this mm to oom_mm_list only if not yet connected. + */ + get_task_struct(tsk); + mm->oom_mm.victim = tsk; + if (!old_tsk) { + atomic_inc(&mm->mm_count); + list_add_tail(&mm->oom_mm.list, &oom_mm_list); + } else { + put_task_struct(old_tsk); + } } /** @@ -1026,6 +1045,9 @@ bool out_of_memory(struct oom_control *oc) return true; } + if (!is_sysrq_oom(oc) && oom_has_pending_mm(oc->memcg, oc->nodemask)) + return true; + p = select_bad_process(oc, &points, totalpages); /* Found nothing?!?! Either we hang forever, or we panic. */ if (!p && !is_sysrq_oom(oc)) { -- 1.8.3.1 -- 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: email@kvack.org