Commit 89996df4 authored May 06, 2009 by J. Bruce Fields

lockd: fix list corruption on lockd restart



If lockd is signalled soon enough after restart then locks_start_grace()
will try to re-add an entry to a list and trigger a lock corruption
warning.

Thanks to Wang Chen for the problem report and diagnosis.

WARNING: at lib/list_debug.c:26 __list_add+0x27/0x5c()
...
list_add corruption. next->prev should be prev (ef8fe958), but was ef8ff128.  (next=ef8ff128).
...
Pid: 23062, comm: lockd Tainted: G        W  2.6.30-rc2 #3
Call Trace:
[<c042d5b5>] warn_slowpath+0x71/0xa0
[<c0422a96>] ? update_curr+0x11d/0x125
[<c044b12d>] ? trace_hardirqs_on_caller+0x18/0x150
[<c044b270>] ? trace_hardirqs_on+0xb/0xd
[<c051c61a>] ? _raw_spin_lock+0x53/0xfa
[<c051c89f>] __list_add+0x27/0x5c
[<ef8f6daa>] locks_start_grace+0x22/0x30 [lockd]
[<ef8f34da>] set_grace_period+0x39/0x53 [lockd]
[<c06b8921>] ? lock_kernel+0x1c/0x28
[<ef8f3558>] lockd+0x64/0x164 [lockd]
[<c044b12d>] ? trace_hardirqs_on_caller+0x18/0x150
[<c04227b0>] ? complete+0x34/0x3e
[<ef8f34f4>] ? lockd+0x0/0x164 [lockd]
[<ef8f34f4>] ? lockd+0x0/0x164 [lockd]
[<c043dd42>] kthread+0x45/0x6b
[<c043dcfd>] ? kthread+0x0/0x6b
[<c0403c23>] kernel_thread_helper+0x7/0x10

Reported-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: stable@kernel.org

parent b2c0cea6

fs/lockd/svc.c

+11 −4

Original line number	Diff line number	Diff line
		@@ -104,6 +104,16 @@ static void set_grace_period(void)
		schedule_delayed_work(&grace_period_end, grace_period);
		}

		static void restart_grace(void)
		{
		if (nlmsvc_ops) {
		cancel_delayed_work_sync(&grace_period_end);
		locks_end_grace(&lockd_manager);
		nlmsvc_invalidate_all();
		set_grace_period();
		}
		}

		/*
		* This is the lockd kernel thread
		*/
		@@ -149,10 +159,7 @@ lockd(void *vrqstp)

		if (signalled()) {
		flush_signals(current);
		if (nlmsvc_ops) {
		nlmsvc_invalidate_all();
		set_grace_period();
		}
		restart_grace();
		continue;
		}

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