Appears consistently during boot up.
$ uname -a
Linux hostname 3.14.0-rc1-24x7+ #8 SMP Fri Feb 7 15:32:43 CST 2014 ppc64 ppc64
ppc64 GNU/Linux
[ 1.953983] audit: type=1403 audit(1391808989.120:3): policy loaded
auid=4294967295 ses=4294967295
[ 1.957980] systemd[1]: Successfully loaded SELinux policy in 323.280ms.
[ 2.048622] systemd[1]: Relabelled /dev and /run in 22.877ms.
[ 2.080219] ======================================================
[ 2.080223] [ INFO: possible circular locking dependency detected ]
[ 2.080227] 3.14.0-rc1-24x7+ #8 Tainted: G W
[ 2.080230] -------------------------------------------------------
[ 2.080234] systemd/1 is trying to acquire lock:
[ 2.080238] (&mm->mmap_sem){++++++}, at: [<c00000000021fe18>]
.might_fault+0x78/0xe0
[ 2.080249]
but task is already holding lock:
[ 2.080253] (&(&ip->i_lock)->mr_lock){++++..}, at: [<c00000000042e7ec>]
.xfs_ilock+0x15c/0x1b0
[ 2.080262]
which lock already depends on the new lock.
[ 2.080267]
the existing dependency chain (in reverse order) is:
[ 2.080271]
-> #1 (&(&ip->i_lock)->mr_lock){++++..}:
[ 2.080278]
-> #0 (&mm->mmap_sem){++++++}:
[ 2.080284]
other info that might help us debug this:
[ 2.080289] Possible unsafe locking scenario:
[ 2.080292] CPU0 CPU1
[ 2.080295] ---- ----
[ 2.080298] lock(&(&ip->i_lock)->mr_lock);
[ 2.080303] lock(&mm->mmap_sem);
[ 2.080307] lock(&(&ip->i_lock)->mr_lock);
[ 2.080312] lock(&mm->mmap_sem);
[ 2.080316]
*** DEADLOCK ***
[ 2.080321] 2 locks held by systemd/1:
[ 2.080323] #0: (&type->i_mutex_dir_key#2){+.+.+.}, at:
[<c000000000297470>] .iterate_dir+0xa0/0x160
[ 2.080334] #1: (&(&ip->i_lock)->mr_lock){++++..}, at:
[<c00000000042e7ec>] .xfs_ilock+0x15c/0x1b0
[ 2.080343]
stack backtrace:
[ 2.080348] CPU: 2 PID: 1 Comm: systemd Tainted: G W
3.14.0-rc1-24x7+ #8
[ 2.080353] Call Trace:
[ 2.080357] [c0000001fa103370] [c000000000016590] .show_stack+0x170/0x290
(unreliable)
[ 2.080364] [c0000001fa103460] [c000000000934f5c] .dump_stack+0xa0/0xdc
[ 2.080370] [c0000001fa1034e0] [c00000000092b6b4]
.print_circular_bug+0x364/0x39c
[ 2.080376] [c0000001fa103590] [c00000000010ba70] .check_prev_add+0x8d0/0x8e0
[ 2.080381] [c0000001fa1036a0] [c00000000010c364]
.validate_chain.isra.31+0x8e4/0xc40
[ 2.080386] [c0000001fa103790] [c00000000010de08] .__lock_acquire+0x488/0xd40
[ 2.080391] [c0000001fa1038b0] [c00000000010f08c] .lock_acquire+0xac/0x190
[ 2.080397] [c0000001fa103980] [c00000000021fe44] .might_fault+0xa4/0xe0
[ 2.080402] [c0000001fa1039f0] [c000000000297924] .filldir+0x1f4/0x290
[ 2.080407] [c0000001fa103ab0] [c0000000003cebc8]
.xfs_dir2_block_getdents+0x218/0x2b0
[ 2.080413] [c0000001fa103b80] [c0000000003cf1e8] .xfs_readdir+0x168/0x1d0
[ 2.080418] [c0000001fa103c30] [c0000000003d2508] .xfs_file_readdir+0x48/0x80
[ 2.080423] [c0000001fa103cc0] [c0000000002974ec] .iterate_dir+0x11c/0x160
[ 2.080428] [c0000001fa103d60] [c000000000297df0] .SyS_getdents+0xa0/0x190
[ 2.080433] [c0000001fa103e30] [c00000000000a164] syscall_exit+0x0/0x98
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