From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D72CC48BD3 for ; Wed, 26 Jun 2019 06:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 381F320B7C for ; Wed, 26 Jun 2019 06:38:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561531102; bh=Dsngz75U/MQ1823N2+4bzZfpbttg8K8rqhFxayKYhQ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zupOdypULpZnZVwKJKLXAHVrWrqXEyJCJjw8xssTX6cm4/Qbn9w5hqcUkGdhPr5EB oLPiV9Sgcj86Wu658OphhO0ESaculqEEOKW7ydc3VUfSfKs53rUYEkJr+9nVVy/Pc1 3HhkYL3O5XUkC7ngEzPU2uzy1skfCpFsT2to4TCg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726835AbfFZGiU (ORCPT ); Wed, 26 Jun 2019 02:38:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:34166 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725876AbfFZGiT (ORCPT ); Wed, 26 Jun 2019 02:38:19 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 47437AEC6; Wed, 26 Jun 2019 06:38:17 +0000 (UTC) Date: Wed, 26 Jun 2019 08:38:16 +0200 From: Michal Hocko To: Shakeel Butt Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Roman Gushchin , David Rientjes , KOSAKI Motohiro , Tetsuo Handa , Paul Jackson , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/3] mm, oom: remove redundant task_in_mem_cgroup() check Message-ID: <20190626063755.GI17798@dhcp22.suse.cz> References: <20190624212631.87212-1-shakeelb@google.com> <20190624212631.87212-2-shakeelb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190624212631.87212-2-shakeelb@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 24-06-19 14:26:30, Shakeel Butt wrote: > oom_unkillable_task() can be called from three different contexts i.e. > global OOM, memcg OOM and oom_score procfs interface. At the moment > oom_unkillable_task() does a task_in_mem_cgroup() check on the given > process. Since there is no reason to perform task_in_mem_cgroup() > check for global OOM and oom_score procfs interface, those contexts > provide NULL memcg and skips the task_in_mem_cgroup() check. However for > memcg OOM context, the oom_unkillable_task() is always called from > mem_cgroup_scan_tasks() and thus task_in_mem_cgroup() check becomes > redundant. So, just remove the task_in_mem_cgroup() check altogether. Just a nit. Not only it is redundant but it is effectively a dead code after your previous patch. > Signed-off-by: Shakeel Butt > Signed-off-by: Tetsuo Handa Acked-by: Michal Hocko Thanks! > --- > Changelog since v2: > - Further divided the patch into two patches. > - Incorporated the task_in_mem_cgroup() from Tetsuo. > > Changelog since v1: > - Divide the patch into two patches. > > fs/proc/base.c | 2 +- > include/linux/memcontrol.h | 7 ------- > include/linux/oom.h | 2 +- > mm/memcontrol.c | 26 -------------------------- > mm/oom_kill.c | 19 +++++++------------ > 5 files changed, 9 insertions(+), 47 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index b8d5d100ed4a..5eacce5e924a 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -532,7 +532,7 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns, > unsigned long totalpages = totalram_pages() + total_swap_pages; > unsigned long points = 0; > > - points = oom_badness(task, NULL, NULL, totalpages) * > + points = oom_badness(task, NULL, totalpages) * > 1000 / totalpages; > seq_printf(m, "%lu\n", points); > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 9abf31bbe53a..2cbce1fe7780 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -407,7 +407,6 @@ static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat, > > struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *); > > -bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg); > struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); > > struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm); > @@ -896,12 +895,6 @@ static inline bool mm_match_cgroup(struct mm_struct *mm, > return true; > } > > -static inline bool task_in_mem_cgroup(struct task_struct *task, > - const struct mem_cgroup *memcg) > -{ > - return true; > -} > - > static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) > { > return NULL; > diff --git a/include/linux/oom.h b/include/linux/oom.h > index d07992009265..b75104690311 100644 > --- a/include/linux/oom.h > +++ b/include/linux/oom.h > @@ -108,7 +108,7 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm) > bool __oom_reap_task_mm(struct mm_struct *mm); > > extern unsigned long oom_badness(struct task_struct *p, > - struct mem_cgroup *memcg, const nodemask_t *nodemask, > + const nodemask_t *nodemask, > unsigned long totalpages); > > extern bool out_of_memory(struct oom_control *oc); > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index db46a9dc37ab..27c92c2b99be 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1259,32 +1259,6 @@ void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru, > *lru_size += nr_pages; > } > > -bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg) > -{ > - struct mem_cgroup *task_memcg; > - struct task_struct *p; > - bool ret; > - > - p = find_lock_task_mm(task); > - if (p) { > - task_memcg = get_mem_cgroup_from_mm(p->mm); > - task_unlock(p); > - } else { > - /* > - * All threads may have already detached their mm's, but the oom > - * killer still needs to detect if they have already been oom > - * killed to prevent needlessly killing additional tasks. > - */ > - rcu_read_lock(); > - task_memcg = mem_cgroup_from_task(task); > - css_get(&task_memcg->css); > - rcu_read_unlock(); > - } > - ret = mem_cgroup_is_descendant(task_memcg, memcg); > - css_put(&task_memcg->css); > - return ret; > -} > - > /** > * mem_cgroup_margin - calculate chargeable space of a memory cgroup > * @memcg: the memory cgroup > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index bd80997e0969..e0cdcbd58b0b 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -153,17 +153,13 @@ static inline bool is_memcg_oom(struct oom_control *oc) > > /* return true if the task is not adequate as candidate victim task. */ > static bool oom_unkillable_task(struct task_struct *p, > - struct mem_cgroup *memcg, const nodemask_t *nodemask) > + const nodemask_t *nodemask) > { > if (is_global_init(p)) > return true; > if (p->flags & PF_KTHREAD) > return true; > > - /* When mem_cgroup_out_of_memory() and p is not member of the group */ > - if (memcg && !task_in_mem_cgroup(p, memcg)) > - return true; > - > /* p may not have freeable memory in nodemask */ > if (!has_intersects_mems_allowed(p, nodemask)) > return true; > @@ -194,20 +190,19 @@ static bool is_dump_unreclaim_slabs(void) > * oom_badness - heuristic function to determine which candidate task to kill > * @p: task struct of which task we should calculate > * @totalpages: total present RAM allowed for page allocation > - * @memcg: task's memory controller, if constrained > * @nodemask: nodemask passed to page allocator for mempolicy ooms > * > * The heuristic for determining which task to kill is made to be as simple and > * predictable as possible. The goal is to return the highest value for the > * task consuming the most memory to avoid subsequent oom failures. > */ > -unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, > +unsigned long oom_badness(struct task_struct *p, > const nodemask_t *nodemask, unsigned long totalpages) > { > long points; > long adj; > > - if (oom_unkillable_task(p, memcg, nodemask)) > + if (oom_unkillable_task(p, nodemask)) > return 0; > > p = find_lock_task_mm(p); > @@ -318,7 +313,7 @@ static int 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)) > + if (oom_unkillable_task(task, oc->nodemask)) > goto next; > > /* > @@ -342,7 +337,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg) > goto select; > } > > - points = oom_badness(task, NULL, oc->nodemask, oc->totalpages); > + points = oom_badness(task, oc->nodemask, oc->totalpages); > if (!points || points < oc->chosen_points) > goto next; > > @@ -390,7 +385,7 @@ static int dump_task(struct task_struct *p, void *arg) > struct oom_control *oc = arg; > struct task_struct *task; > > - if (oom_unkillable_task(p, NULL, oc->nodemask)) > + if (oom_unkillable_task(p, oc->nodemask)) > return 0; > > task = find_lock_task_mm(p); > @@ -1090,7 +1085,7 @@ bool out_of_memory(struct oom_control *oc) > check_panic_on_oom(oc, constraint); > > if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task && > - current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) && > + current->mm && !oom_unkillable_task(current, oc->nodemask) && > current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) { > get_task_struct(current); > oc->chosen = current; > -- > 2.22.0.410.gd8fdbe21b5-goog -- Michal Hocko SUSE Labs