From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1098017-1521803639-2-9319123919941165023 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521803638; b=fDQFE+zH137ryceC4fMbdHju8PO6zf0X9HYOykoqJ+Yl2m6 Y6IWRt/nALq0G1UvAopeDsDACNzsQpZDCNqzT+HEzwVDzNiRR+dcZhva4Q308A+g CEgzqqkl7Kbwb/X/ky/PqimeSDdZnr3VANg4Z017FGv3T7SlUhPhA0lA47wC1/kC k8HiMkO9cgWVRbko9rtgoNvLDC07mnyCSkEL845JndqSwVNmyCzkq2E28JSciblt G4NnEo/AgVd1jr68XiRCYo9fd8wPr9Zi7DkuEnirDT8NtHabfnLKrX49OyionGql 2R8DSJrz9vAiamUnfWuOJp/I+KDDPWHGy9ibv8Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1521803638; bh=KrXuHRqp9xoKorhiK8qYp2qCMC MIh5RjtVtNIUMp9+0=; b=sO2HyLOVmoaipeMof20ugh8beCK2e3oMvLcQQuPw8l jW3qBxcH910F6XieykR69J0BQJybDKIhJ0rxRXvwxxRCN0XeZwgkJ8HdoarjrhF3 BfN3zt92QtlXxUO3MqpLsmcVd/BKz70pB8sBlivTvGr3zgLNhyOINUnFQHMd6iJ/ 6aUw6BTAjrolAXCPB+nVk2cAItpO6pZXcKdN2iwrP4Hj87HtqPw3vzppDh3aA54y NLOS6vQEjoMdeGK25mvS+nq4yO04zmTFYcsZY428DVT8xdrjE+FC9teaPPtkIlIt 1EJbUimgj4QxSJpx3fve+XZpLiBtHDlWPCHlxTx90R8A== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754798AbeCWLNp (ORCPT ); Fri, 23 Mar 2018 07:13:45 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42548 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932681AbeCWKK2 (ORCPT ); Fri, 23 Mar 2018 06:10:28 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Trond Myklebust , Sasha Levin Subject: [PATCH 4.9 123/177] pNFS: Fix a deadlock when coalescing writes and returning the layout Date: Fri, 23 Mar 2018 10:54:11 +0100 Message-Id: <20180323094210.671622255@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180323094205.090519271@linuxfoundation.org> References: <20180323094205.090519271@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust [ Upstream commit 61f454e30c18a28924e96be12592c0d5e24bcc81 ] Consider the following deadlock: Process P1 Process P2 Process P3 ========== ========== ========== lock_page(page) lseg = pnfs_update_layout(inode) lo = NFS_I(inode)->layout pnfs_error_mark_layout_for_return(lo) lock_page(page) lseg = pnfs_update_layout(inode) In this scenario, - P1 has declared the layout to be in error, but P2 holds a reference to a layout segment on that inode, so the layoutreturn is deferred. - P2 is waiting for a page lock held by P3. - P3 is asking for a new layout segment, but is blocked waiting for the layoutreturn. The fix is to ensure that pnfs_error_mark_layout_for_return() does not set the NFS_LAYOUT_RETURN flag, which blocks P3. Instead, we allow the latter to call LAYOUTGET so that it can make progress and unblock P2. Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/nfs/pnfs.c | 2 -- 1 file changed, 2 deletions(-) --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -1953,8 +1953,6 @@ void pnfs_error_mark_layout_for_return(s spin_lock(&inode->i_lock); pnfs_set_plh_return_info(lo, range.iomode, 0); - /* Block LAYOUTGET */ - set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags); /* * mark all matching lsegs so that we are sure to have no live * segments at hand when sending layoutreturn. See pnfs_put_lseg()