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[209.132.183.28]) by mx.google.com with ESMTPS id t6si197575qkm.207.2019.05.15.07.28.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 15 May 2019 07:28:33 -0700 (PDT) Received-SPF: pass (google.com: domain of oleg@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 oleg@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 139C88553A; Wed, 15 May 2019 14:28:33 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.159]) by smtp.corp.redhat.com (Postfix) with SMTP id 147181001DD7; Wed, 15 May 2019 14:28:31 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 15 May 2019 16:28:30 +0200 (CEST) Date: Wed, 15 May 2019 16:28:28 +0200 From: Oleg Nesterov To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: use down_read_killable for locking mmap_sem in access_remote_vm Message-ID: <20190515142828.GA18892@redhat.com> References: <155790847881.2798.7160461383704600177.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155790847881.2798.7160461383704600177.stgit@buzz> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Wed, 15 May 2019 14:28:33 +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: > @@ -4348,7 +4348,9 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, > void *old_buf = buf; > int write = gup_flags & FOLL_WRITE; > > - down_read(&mm->mmap_sem); > + if (down_read_killable(&mm->mmap_sem)) > + return 0; > + I too think that "return 0" looks a bit strange even if correct, to me "return -EINTR" would look better. But I won't insist, this is cosmetic. Acked-by: Oleg Nesterov