On 09/01/2016 01:33 PM, Mike Snitzer wrote:
I'm able to easily reproduce this 100% cpu usage using mptest's
test_02_sdev_delete.
'dmsetup suspend --nolockfs --noflush mp' hangs, seems rooted in your
use of blk_mq_freeze_queue():
[ 298.136930] dmsetup D ffff880142cb3b70 0 9478 9414 0x00000080
[ 298.144831] ffff880142cb3b70 ffff880142cb3b28 ffff880330d6cb00 ffff88032d0022f8
[ 298.153132] ffff880142cb4000 ffff88032d0022f8 ffff88032b161800 0000000000000001
[ 298.161438] 0000000000000001 ffff880142cb3b88 ffffffff816c06e5 ffff88032d001aa0
[ 298.169740] Call Trace:
[ 298.172473] [<ffffffff816c06e5>] schedule+0x35/0x80
[ 298.178019] [<ffffffff8131b937>] blk_mq_freeze_queue_wait+0x57/0xc0
[ 298.185116] [<ffffffff810c58c0>] ? prepare_to_wait_event+0xf0/0xf0
[ 298.192117] [<ffffffff8131d92a>] blk_mq_freeze_queue+0x1a/0x20
[ 298.198734] [<ffffffffa000e910>] dm_stop_queue+0x50/0xc0 [dm_mod]
[ 298.205644] [<ffffffffa0001824>] __dm_suspend+0x134/0x1f0 [dm_mod]
[ 298.212649] [<ffffffffa00035b8>] dm_suspend+0xb8/0xd0 [dm_mod]
[ 298.219270] [<ffffffffa000882e>] dev_suspend+0x18e/0x240 [dm_mod]
[ 298.226175] [<ffffffffa00086a0>] ? table_load+0x380/0x380 [dm_mod]
[ 298.233180] [<ffffffffa0009027>] ctl_ioctl+0x1e7/0x4d0 [dm_mod]
[ 298.239890] [<ffffffff81197f00>] ? lru_cache_add_active_or_unevictable+0x10/0xb0
[ 298.248253] [<ffffffffa0009323>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
[ 298.255049] [<ffffffff81227937>] do_vfs_ioctl+0xa7/0x5d0
[ 298.261081] [<ffffffff8112787f>] ? __audit_syscall_entry+0xaf/0x100
[ 298.268178] [<ffffffff8100365d>] ? syscall_trace_enter+0x1dd/0x2c0
[ 298.275179] [<ffffffff81227ed9>] SyS_ioctl+0x79/0x90
[ 298.280821] [<ffffffff81003a47>] do_syscall_64+0x67/0x160
[ 298.286950] [<ffffffff816c4921>] entry_SYSCALL64_slow_path+0x25/0x25
Hello Mike,
In your dm-4.9 branch I see that you call blk_mq_freeze_queue() while
holding the block layer queue lock. Please don't do this.
blk_mq_freeze_queue() can sleep and as you know calling a sleeping
function while holding a spinlock is not allowed.
Bart.
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