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[209.132.183.28]) by mx.google.com with ESMTPS id s38si797869qta.174.2019.03.02.10.52.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 02 Mar 2019 10:52:17 -0800 (PST) Received-SPF: pass (google.com: domain of aarcange@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of aarcange@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=aarcange@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9C5D4307CEB2; Sat, 2 Mar 2019 18:51:47 +0000 (UTC) Received: from sky.random (ovpn-121-1.rdu2.redhat.com [10.10.121.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 220315D70A; Sat, 2 Mar 2019 18:51:45 +0000 (UTC) Date: Sat, 2 Mar 2019 13:51:44 -0500 From: Andrea Arcangeli To: Jan Stancek Cc: linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, peterz@infradead.org, riel@surriel.com, mhocko@suse.com, ying.huang@intel.com, jrdr.linux@gmail.com, jglisse@redhat.com, aneesh.kumar@linux.ibm.com, david@redhat.com, raquini@redhat.com, rientjes@google.com, kirill@shutemov.name, mgorman@techsingularity.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/memory.c: do_fault: avoid usage of stale vm_area_struct Message-ID: <20190302185144.GD31083@redhat.com> References: <20190302171043.GP11592@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Sat, 02 Mar 2019 18:51:47 +0000 (UTC) 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: Hello Jan, On Sat, Mar 02, 2019 at 07:19:39PM +0100, Jan Stancek wrote: > + struct mm_struct *vm_mm = READ_ONCE(vma->vm_mm); The vma->vm_mm cannot change under gcc there, so no need of READ_ONCE. The release of mmap_sem has release semantics so the vma->vm_mm access cannot be reordered after up_read(mmap_sem) either. Other than the above detail: Reviewed-by: Andrea Arcangeli Thanks, Andrea