Bug#765780: systemd: "systemd-udevd blocked" journal message when writing ISO to USB stick

[Mert Dirik]

Control: reassign -1 src:linux

On Sat, 18 Oct 2014 11:58:07 +1100 Scott Leggett <scott at sl.id.au> wrote:
 > -- Log snippet
 >
 > Oct 17 22:56:56 whist kernel: Tainted: G O 3.16-2-amd64 #1
 > Oct 17 22:56:56 whist kernel: "echo 0 > 
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
 > Oct 17 22:56:56 whist kernel: systemd-udevd D ffff88003686c528 0 313 
1 0x00000000
 > Oct 17 22:56:56 whist kernel: ffff88003686c0d0 0000000000000086 
0000000000014240 ffff88040ce6ffd8
 > Oct 17 22:56:56 whist kernel: 0000000000014240 ffff88003686c0d0 
ffff88040d5951d8 ffff88040ce6fbe0
 > Oct 17 22:56:56 whist kernel: ffff88040d5951dc ffff88003686c0d0 
00000000ffffffff ffff88040d5951e0
 > Oct 17 22:56:56 whist kernel: Call Trace:
 > Oct 17 22:56:56 whist kernel: [<ffffffff81508e35>] ? 
schedule_preempt_disabled+0x25/0x70
 > Oct 17 22:56:56 whist kernel: [<ffffffff8150a8f3>] ? 
__mutex_lock_slowpath+0xd3/0x1c0
 > Oct 17 22:56:56 whist kernel: [<ffffffff8150a9fb>] ? mutex_lock+0x1b/0x2a
 > Oct 17 22:56:56 whist kernel: [<ffffffff811d9733>] ? 
__blkdev_get+0x63/0x480
 > Oct 17 22:56:56 whist kernel: [<ffffffff811d9ea0>] ? 
blkdev_get_by_dev+0x40/0x40
 > Oct 17 22:56:56 whist kernel: [<ffffffff811d9d06>] ? 
blkdev_get+0x1b6/0x310
 > Oct 17 22:56:56 whist kernel: [<ffffffff811d9ea0>] ? 
blkdev_get_by_dev+0x40/0x40
 > Oct 17 22:56:56 whist kernel: [<ffffffff811a2ce2>] ? 
do_dentry_open+0x1f2/0x330
 > Oct 17 22:56:56 whist kernel: [<ffffffff811a2fed>] ? 
finish_open+0x2d/0x40
 > Oct 17 22:56:56 whist kernel: [<ffffffff811b3aca>] ? do_last+0xa5a/0x11e0
 > Oct 17 22:56:56 whist kernel: [<ffffffff811afef1>] ? 
link_path_walk+0x71/0x890
 > Oct 17 22:56:56 whist kernel: [<ffffffff811b430b>] ? 
path_openat+0xbb/0x680
 > Oct 17 22:56:56 whist kernel: [<ffffffff81177835>] ? 
free_pages_and_swap_cache+0x95/0xb0
 > Oct 17 22:56:56 whist kernel: [<ffffffff811b507a>] ? 
do_filp_open+0x3a/0x90
 > Oct 17 22:56:56 whist kernel: [<ffffffff811c10ac>] ? 
__alloc_fd+0x7c/0x120
 > Oct 17 22:56:56 whist kernel: [<ffffffff811a4529>] ? 
do_sys_open+0x129/0x220
 > Oct 17 22:56:56 whist kernel: [<ffffffff8150c26d>] ? 
system_call_fast_compare_end+0x10/0x15
 > Oct 17 22:58:56 whist kernel: INFO: task systemd-udevd:313 blocked 
for more than 120 seconds.
 > Oct 17 22:58:56 whist kernel: Tainted: G O 3.16-2-amd64 #1
 > Oct 17 22:58:56 whist kernel: "echo 0 > 
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
 > Oct 17 22:58:56 whist kernel: systemd-udevd D ffff88003686c528 0 313 
1 0x00000000
 > Oct 17 22:58:56 whist kernel: ffff88003686c0d0 0000000000000086 
0000000000014240 ffff88040ce6ffd8
 > Oct 17 22:58:56 whist kernel: 0000000000014240 ffff88003686c0d0 
ffff88040d5951d8 ffff88040ce6fbe0
 > Oct 17 22:58:56 whist kernel: ffff88040d5951dc ffff88003686c0d0 
00000000ffffffff ffff88040d5951e0
 > Oct 17 22:58:56 whist kernel: Call Trace:
 > Oct 17 22:58:56 whist kernel: [<ffffffff81508e35>] ? 
schedule_preempt_disabled+0x25/0x70
 > Oct 17 22:58:56 whist kernel: [<ffffffff8150a8f3>] ? 
__mutex_lock_slowpath+0xd3/0x1c0
 > Oct 17 22:58:56 whist kernel: [<ffffffff8150a9fb>] ? mutex_lock+0x1b/0x2a
 > Oct 17 22:58:56 whist kernel: [<ffffffff811d9733>] ? 
__blkdev_get+0x63/0x480
 > Oct 17 22:58:56 whist kernel: [<ffffffff811d9ea0>] ? 
blkdev_get_by_dev+0x40/0x40
 > Oct 17 22:58:56 whist kernel: [<ffffffff811d9d06>] ? 
blkdev_get+0x1b6/0x310
 > Oct 17 22:58:56 whist kernel: [<ffffffff811d9ea0>] ? 
blkdev_get_by_dev+0x40/0x40
 > Oct 17 22:58:56 whist kernel: [<ffffffff811a2ce2>] ? 
do_dentry_open+0x1f2/0x330
 > Oct 17 22:58:56 whist kernel: [<ffffffff811a2fed>] ? 
finish_open+0x2d/0x40
 > Oct 17 22:58:56 whist kernel: [<ffffffff811b3aca>] ? do_last+0xa5a/0x11e0
 > Oct 17 22:58:56 whist kernel: [<ffffffff811afef1>] ? 
link_path_walk+0x71/0x890
 > Oct 17 22:58:56 whist kernel: [<ffffffff811b430b>] ? 
path_openat+0xbb/0x680
 > Oct 17 22:58:56 whist kernel: [<ffffffff81177835>] ? 
free_pages_and_swap_cache+0x95/0xb0

This looks more like a kernel bug. I'm assigning it to src:linux
Dear linux maintainers: Apologies in advance if you don't think it's a 
kernel bug.