From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail177-1.suw61.mandrillapp.com ([198.2.177.1]:59090 "EHLO mail177-1.suw61.mandrillapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752522AbcCAIPy (ORCPT ); Tue, 1 Mar 2016 03:15:54 -0500 Received: from pmta06.mandrill.prod.suw01.rsglab.com (127.0.0.1) by mail177-1.suw61.mandrillapp.com id hql7rk22rtk4 for ; Tue, 1 Mar 2016 08:15:40 +0000 (envelope-from ) From: Subject: Patch "dealing with the rest of shrink_dentry_list() livelock" has been added to the 3.14-stable tree To: , Cc: , Message-Id: <145681500022410@kroah.com> Date: Tue, 01 Mar 2016 08:15:40 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled dealing with the rest of shrink_dentry_list() livelock to the 3.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: dealing-with-the-rest-of-shrink_dentry_list-livelock.patch and it can be found in the queue-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From b2b80195d8829921506880f6dccd21cabd163d0d Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 29 May 2014 09:11:45 -0400 Subject: dealing with the rest of shrink_dentry_list() livelock From: Al Viro commit b2b80195d8829921506880f6dccd21cabd163d0d upstream. We have the same problem with ->d_lock order in the inner loop, where we are dropping references to ancestors. Same solution, basically - instead of using dentry_kill() we use lock_parent() (introduced in the previous commit) to get that lock in a safe way, recheck ->d_count (in case if lock_parent() has ended up dropping and retaking ->d_lock and somebody managed to grab a reference during that window), trylock the inode->i_lock and use __dentry_kill() to do the rest. Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/dcache.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) --- a/fs/dcache.c +++ b/fs/dcache.c @@ -886,8 +886,26 @@ static void shrink_dentry_list(struct li * fragmentation. */ dentry = parent; - while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) - dentry = dentry_kill(dentry, 1); + while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { + parent = lock_parent(dentry); + if (dentry->d_lockref.count != 1) { + dentry->d_lockref.count--; + spin_unlock(&dentry->d_lock); + if (parent) + spin_unlock(&parent->d_lock); + break; + } + inode = dentry->d_inode; /* can't be NULL */ + if (unlikely(!spin_trylock(&inode->i_lock))) { + spin_unlock(&dentry->d_lock); + if (parent) + spin_unlock(&parent->d_lock); + cpu_relax(); + continue; + } + __dentry_kill(dentry); + dentry = parent; + } } } Patches currently in stable-queue which might be from viro@zeniv.linux.org.uk are queue-3.14/lock_parent-don-t-step-on-stale-d_parent-of-all-but-freed-one.patch queue-3.14/lift-the-already-marked-killed-case-into-shrink_dentry_list.patch queue-3.14/expand-dentry_kill-dentry-0-in-shrink_dentry_list.patch queue-3.14/bcache-fix-a-leak-in-bch_cached_dev_run.patch queue-3.14/dcache-add-missing-lockdep-annotation.patch queue-3.14/dealing-with-the-rest-of-shrink_dentry_list-livelock.patch queue-3.14/split-dentry_kill.patch queue-3.14/shrink_dentry_list-take-parent-s-d_lock-earlier.patch queue-3.14/dentry_kill-doesn-t-need-the-second-argument-now.patch