From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754041AbeCFTFF (ORCPT ); Tue, 6 Mar 2018 14:05:05 -0500 Received: from foss.arm.com ([217.140.101.70]:43130 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750838AbeCFTFE (ORCPT ); Tue, 6 Mar 2018 14:05:04 -0500 From: Will Deacon To: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, torvalds@linux-foundation.org Cc: peterz@infradead.org, willy@infradead.org, linux-kernel@vger.kernel.org, Will Deacon Subject: [RESEND PATCHv2 2/2] fs: dcache: Use READ_ONCE when accessing i_dir_seq Date: Tue, 6 Mar 2018 19:05:06 +0000 Message-Id: <1520363106-4687-3-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1520363106-4687-1-git-send-email-will.deacon@arm.com> References: <1520363106-4687-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org i_dir_seq is subject to concurrent modification by a cmpxchg or store-release operation, so ensure that the relaxed access in d_alloc_parallel uses READ_ONCE. Reported-by: Peter Zijlstra Signed-off-by: Will Deacon --- fs/dcache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dcache.c b/fs/dcache.c index b243deec298c..5716ab04e1db 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2502,7 +2502,7 @@ struct dentry *d_alloc_parallel(struct dentry *parent, } hlist_bl_lock(b); - if (unlikely(parent->d_inode->i_dir_seq != seq)) { + if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) { hlist_bl_unlock(b); rcu_read_unlock(); goto retry; -- 2.1.4