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[217.140.101.70]) by mx.google.com with ESMTP id o21si805324ejm.141.2019.05.18.02.47.25 for ; Sat, 18 May 2019 02:47:25 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of catalin.marinas@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9AE37341; Sat, 18 May 2019 02:47:24 -0700 (PDT) Received: from mbp (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6D64A3F703; Sat, 18 May 2019 02:47:23 -0700 (PDT) Date: Sat, 18 May 2019 10:47:20 +0100 From: Catalin Marinas To: Dmitry Vyukov Cc: Andrew Morton , Dmitry Vyukov , Linux-MM , LKML Subject: Re: [PATCH] kmemleak: fix check for softirq context Message-ID: <20190518094719.gyvhbdrwmcv4diax@mbp> References: <20190517171507.96046-1-dvyukov@gmail.com> <20190517143746.2157a759f65b4cbc73321124@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) 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 Sat, May 18, 2019 at 09:10:59AM +0200, Dmitry Vyukov wrote: > On Fri, May 17, 2019 at 11:37 PM Andrew Morton > wrote: > > On Fri, 17 May 2019 19:15:07 +0200 Dmitry Vyukov wrote: > > > > > From: Dmitry Vyukov > > > > > > in_softirq() is a wrong predicate to check if we are in a softirq context. > > > It also returns true if we have BH disabled, so objects are falsely > > > stamped with "softirq" comm. The correct predicate is in_serving_softirq(). > > > > > > ... > > > > > > --- a/mm/kmemleak.c > > > +++ b/mm/kmemleak.c > > > @@ -588,7 +588,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size, > > > if (in_irq()) { > > > object->pid = 0; > > > strncpy(object->comm, "hardirq", sizeof(object->comm)); > > > - } else if (in_softirq()) { > > > + } else if (in_serving_softirq()) { > > > object->pid = 0; > > > strncpy(object->comm, "softirq", sizeof(object->comm)); > > > } else { > > > > What are the user-visible runtime effects of this change? > > If user does cat from /sys/kernel/debug/kmemleak previously they would > see this, which is clearly wrong, this is system call context (see the > comm): Indeed, with your patch you get the correct output. Acked-by: Catalin Marinas Thanks. -- Catalin