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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=no 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 18AACC28CBC for ; Wed, 6 May 2020 12:47:10 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E083820746 for ; Wed, 6 May 2020 12:47:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ib1a4hRf"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="iZaSTh0z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E083820746 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=LJWlnpt2vgFteO7pkki+HrrxUk9Phi+N7c6RmBWY/3g=; b=ib1a4hRf3IszEv HWvTLNLJ/zm4v3fg7vlbjChKKn2dEjhN6p4JdWPmv46kzgEGsvHoBseGlrlW0e2NsV0ySTgmBkmwp AwkP1wbid4ld6HDhpl5ioRv+IMbp/xxUeTpjpyy/XF6MYeVXB8Q0Pq/anxupRVefDAQUK9UTPaVGV eo28omTFNI2/L8Wl9kJeq8p6UON+iaMJ//tTGIdRpqX47bQ1V8u9Mq2o9XDE2nKEz/an1nrgtWU12 asOdoNDrhuAjnEuR1ewTLRtm81xseFbrwjdFbOUOevz3nu7+WzGhWmayI4to8T6EUNjl/SKxs4M3a TSlmdv566mYa1Y5qCQjQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWJS7-0002j8-1Y; Wed, 06 May 2020 12:47:07 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWJS4-0002ij-0D for linux-nvme@lists.infradead.org; Wed, 06 May 2020 12:47:05 +0000 Received: from C02WT3WMHTD6 (unknown [8.36.226.102]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DA03E206DD; Wed, 6 May 2020 12:47:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588769223; bh=VHzu0MBUtdgucXSH6sLfvHaP5Lh1OhKZu5LBcxBkhZU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iZaSTh0z6ETMG0odXB+F/r3N9aEL8oMnXBbsqiwLlEcR1IzLtE70a4BRYRB4gGd7x /0zoL0w9GBqBouuT6tJRD2usIxKK/X3LjMNw9GsYSPAy8OPXoG4Ikb2G4/42dNlwwz mCJNGixSlnX5yXbTzm/wvWBPd1Bi6cpz8H+wGfWI= Date: Wed, 6 May 2020 06:47:01 -0600 From: Keith Busch To: John Garry Subject: Re: [PATCH] nvme-pci: slimmer CQ head update Message-ID: <20200506124701.GA54933@C02WT3WMHTD6> References: <20200228184519.GA2281@avx2> <20200229055351.GA542920@dhcp-10-100-145-180.wdl.wdc.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200506_054704_086625_286E8E93 X-CRM114-Status: GOOD ( 12.37 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: axboe@fb.com, sagi@grimberg.me, Alexey Dobriyan , linux-nvme@lists.infradead.org, hch@lst.de Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, May 06, 2020 at 12:03:35PM +0100, John Garry wrote: > On 29/02/2020 05:53, Keith Busch wrote: > > On Fri, Feb 28, 2020 at 09:45:19PM +0300, Alexey Dobriyan wrote: > > > static inline void nvme_update_cq_head(struct nvme_queue *nvmeq) > > > { > > > - if (nvmeq->cq_head == nvmeq->q_depth - 1) { > > > + if (++nvmeq->cq_head == nvmeq->q_depth) { > > I figure momentarily nvmeq->cq_head may transition to equal nvmeq->q_depth > and then to 0, which causes an out-of-bounds access here: > > static inline bool nvme_cqe_pending(struct nvme_queue *nvmeq) > { > return (le16_to_cpu(nvmeq->cqes[nvmeq->cq_head].status) & 1) == > nvmeq->cq_phase; > } Thanks for the notice, your analysis sounds correct to me. Ideally we wouldn't let the irq check happen while the threaded handler is running, but that is a bit risky to introduce at this point. I'm okay with reverting to fix this issue. _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme