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Date: Tue, 27 May 2014 20:11:08 +0200
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To: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: 3.15-rc6 - btrfs-transacti:4157 blocked for more than 120 seconds.
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Sender: linux-btrfs-owner@vger.kernel.org
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Hi,

Btrfs-transaction keeps blocking for me on all 3.15-rc versions.
3.14 does not have this issue.
The process never gets unstuck. btrfs fi sync does not help. A hard 
reboot seems to be the only way to recover.

The volume is still readable when it's in this state.

dmesg + sysrq-w is available at http://pastebin.com/vHQnRE2F
It's over 6000 lines, and would most likely not be allowed on the list.

The blocking happons on a server with local kvm-clients reading and 
writing to a local btrfs-volume over nfs.
The btrfs-volume is on top of dm-crypt devices.

Any additional info I can give to help?
Tests you want me to run?

--
Torbjørn

--snip--
[138011.263478] INFO: task btrfs-transacti:4157 blocked for more than 
120 seconds.
[138011.263558]       Tainted: G            E 3.15.0-rc6 #58
[138011.263605] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[138011.263687] btrfs-transacti D ffff88042fc94500     0  4157 2 0x00000000
[138011.263744]  ffff880400737e10 0000000000000002 ffff880403b33260 
ffff880400737fd8
[138011.263831]  0000000000014500 0000000000014500 ffff88041973b260 
ffff8802a9c97b40
[138011.263919]  ffff880403a0e800 ffff880400737e30 ffff8800c950ac00 
ffff8800c950ac58
[138011.264007] Call Trace:
[138011.264045]  [<ffffffff816f81a9>] schedule+0x29/0x70
[138011.264097]  [<ffffffffa01a6f65>] 
btrfs_commit_transaction+0x315/0xa10 [btrfs]
[138011.264178]  [<ffffffff810acf40>] ? prepare_to_wait_event+0x100/0x100
[138011.264235]  [<ffffffffa01a2ea5>] transaction_kthread+0x1b5/0x240 
[btrfs]
[138011.264293]  [<ffffffffa01a2cf0>] ? 
btrfs_cleanup_transaction+0x560/0x560 [btrfs]
[138011.264376]  [<ffffffff81088e72>] kthread+0xd2/0xf0
[138011.264422]  [<ffffffff81088da0>] ? kthread_create_on_node+0x190/0x190
[138011.264475]  [<ffffffff81704dfc>] ret_from_fork+0x7c/0xb0
[138011.264522]  [<ffffffff81088da0>] ? kthread_create_on_node+0x190/0x190
--snip--