This is a note to let you know that I've just added the patch titled
lockd: fix lockd shutdown race
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: lockd-fix-lockd-shutdown-race.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: "J. Bruce Fields" bfields@redhat.com Date: Tue, 28 Mar 2017 21:25:08 -0400 Subject: lockd: fix lockd shutdown race
From: "J. Bruce Fields" bfields@redhat.com
[ Upstream commit efda760fe95ea15291853c8fa9235c32d319cd98 ]
As reported by David Jeffery: "a signal was sent to lockd while lockd was shutting down from a request to stop nfs. The signal causes lockd to call restart_grace() which puts the lockd_net structure on the grace list. If this signal is received at the wrong time, it will occur after lockd_down_net() has called locks_end_grace() but before lockd_down_net() stops the lockd thread. This leads to lockd putting the lockd_net structure back on the grace list, then exiting without anything removing it from the list."
So, perform the final locks_end_grace() from the the lockd thread; this ensures it's serialized with respect to restart_grace().
Reported-by: David Jeffery djeffery@redhat.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/lockd/svc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -129,6 +129,8 @@ lockd(void *vrqstp) { int err = 0; struct svc_rqst *rqstp = vrqstp; + struct net *net = &init_net; + struct lockd_net *ln = net_generic(net, lockd_net_id);
/* try_to_freeze() is called from svc_recv() */ set_freezable(); @@ -173,6 +175,8 @@ lockd(void *vrqstp) if (nlmsvc_ops) nlmsvc_invalidate_all(); nlm_shutdown_hosts(); + cancel_delayed_work_sync(&ln->grace_period_end); + locks_end_grace(&ln->lockd_manager); return 0; }
@@ -267,8 +271,6 @@ static void lockd_down_net(struct svc_se if (ln->nlmsvc_users) { if (--ln->nlmsvc_users == 0) { nlm_shutdown_hosts_net(net); - cancel_delayed_work_sync(&ln->grace_period_end); - locks_end_grace(&ln->lockd_manager); svc_shutdown_net(serv, net); dprintk("lockd_down_net: per-net data destroyed; net=%p\n", net); }
Patches currently in stable-queue which might be from bfields@redhat.com are
queue-4.4/lockd-fix-lockd-shutdown-race.patch