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[209.85.220.65]) by mx.google.com with SMTPS id q12sor1417543ioj.143.2019.06.13.22.58.47 for (Google Transport Security); Thu, 13 Jun 2019 22:58:47 -0700 (PDT) Received-SPF: pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=X10iTjf2; spf=pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=xfMl64b1l75nsr7xDRm1WoxO8Sbiny9xMn/Q+sskA88=; b=X10iTjf2YAh/l8wNceM7dmieEfVyTVpJybUYZSp2dcBcDuUSwtgKjZIXAJvg6sUYat QaelgX0303nRzD6LZDEILXFJC+Uqj7VCwwzG8V1WcLuTsn53NnKYIe3HMAlaMfBRa1mg 1PX9QYmx2R0cle9/dMfdqfdrPYs2F141+DMjtfFk844IL8MaTFfYctMKVfogCkKMMvgT uKK34ZYySqS1bzdm5ntqIzSpXPoi3n4b+TFnVz+MCxM+c9S9nhp04wMyEgKvnzrYBWo7 +D+z2Xt0ULa9/lHzEFP2YL3XP6UmG9+RnNFgXia043kPqFVZemjE4FTRRdFVc0+oc9Xd aF6Q== X-Google-Smtp-Source: APXvYqzaQi3CocQJKKKC+kLD0gjwexch9vLNaX2TcAYrgaOKwf3+Vj1MzFZyVc/gtKXN+jUu/n3a/sSW9G4Tx9wv3rY= X-Received: by 2002:a6b:3b4d:: with SMTP id i74mr21644007ioa.207.1560491927200; Thu, 13 Jun 2019 22:58:47 -0700 (PDT) MIME-Version: 1.0 References: <1560434150-13626-1-git-send-email-laoar.shao@gmail.com> <20190613185640.GA1405@dhcp22.suse.cz> In-Reply-To: <20190613185640.GA1405@dhcp22.suse.cz> From: Yafang Shao Date: Fri, 14 Jun 2019 13:58:11 +0800 Message-ID: Subject: Re: [PATCH] mm/oom_kill: set oc->constraint in constrained_alloc() To: Michal Hocko Cc: Andrew Morton , Linux MM , yuzhoujian Content-Type: text/plain; charset="UTF-8" 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: On Fri, Jun 14, 2019 at 2:56 AM Michal Hocko wrote: > > On Thu 13-06-19 21:55:50, Yafang Shao wrote: > > In dump_oom_summary() oc->constraint is used to show > > oom_constraint_text, but it hasn't been set before. > > So the value of it is always the default value 0. > > We should set it in constrained_alloc(). > > Thanks for catching that. > > > Bellow is the output when memcg oom occurs, > > > > before this patch: > > [ 133.078102] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null), > > cpuset=/,mems_allowed=0,oom_memcg=/foo,task_memcg=/foo,task=bash,pid=7997,uid=0 > > > > after this patch: > > [ 952.977946] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null), > > cpuset=/,mems_allowed=0,oom_memcg=/foo,task_memcg=/foo,task=bash,pid=13681,uid=0 > > > > unless I am missing something > Fixes: ef8444ea01d7 ("mm, oom: reorganize the oom report in dump_header") > > The patch looks correct but I think it is more complicated than it needs > to be. Can we do the following instead? > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 5a58778c91d4..f719b64741d6 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -987,8 +987,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message) > /* > * Determines whether the kernel must panic because of the panic_on_oom sysctl. > */ > -static void check_panic_on_oom(struct oom_control *oc, > - enum oom_constraint constraint) > +static void check_panic_on_oom(struct oom_control *oc) > { > if (likely(!sysctl_panic_on_oom)) > return; > @@ -998,7 +997,7 @@ static void check_panic_on_oom(struct oom_control *oc, > * does not panic for cpuset, mempolicy, or memcg allocation > * failures. > */ > - if (constraint != CONSTRAINT_NONE) > + if (oc->constraint != CONSTRAINT_NONE) > return; > } > /* Do not panic for oom kills triggered by sysrq */ > @@ -1035,7 +1034,6 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifier); > bool out_of_memory(struct oom_control *oc) > { > unsigned long freed = 0; > - enum oom_constraint constraint = CONSTRAINT_NONE; > > if (oom_killer_disabled) > return false; > @@ -1071,10 +1069,10 @@ bool out_of_memory(struct oom_control *oc) > * Check if there were limitations on the allocation (only relevant for > * NUMA and memcg) that may require different handling. > */ > - constraint = constrained_alloc(oc); > - if (constraint != CONSTRAINT_MEMORY_POLICY) > + oc->constraint = constrained_alloc(oc); > + if (oc->constraint != CONSTRAINT_MEMORY_POLICY) > oc->nodemask = NULL; > - check_panic_on_oom(oc, constraint); > + check_panic_on_oom(oc); > > if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task && > current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) && > > I guess the current confusion comes from the fact that we have > constraint both in the oom_control and a local variable so I would > rather remove that. What do you think? Remove the local variable is fine by me. Thanks Yafang