On 03/30/2014 01:47 PM, Sitsofe Wheeler wrote:

Hi,

On Sun, Mar 30, 2014 at 12:53:12PM +0200, Francis Moreau wrote:

quoted

As I was expecting I'm getting new issues with bcache after upgrading my
kernel:

[Mar30 12:24] INFO: task bcache_writebac:155 blocked for more than 120
seconds.
[  +0.000007]       Not tainted 3.13.7-1-ARCH #1
[  +0.000002] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[  +0.000003] bcache_writebac D 0000000000000000     0   155      2
0x00000000
[  +0.000006]  ffff8804049c5eb8 0000000000000046 ffff880405816c00
ffff8804049c5fd8
[  +0.000005]  0000000000014440 0000000000014440 ffff880405816c00
ffff8804049c5e38
[  +0.000004]  ffffffff810925fa 24448b48e0d83524 fa83ffffee31e918
0000000000000046
[  +0.000004] Call Trace:
[  +0.000010]  [<ffffffff810925fa>] ? try_to_wake_up+0x1fa/0x2c0
[  +0.000006]  [<ffffffff81092712>] ? default_wake_function+0x12/0x20
[  +0.000005]  [<ffffffff810a2538>] ? __wake_up_common+0x58/0x90
[  +0.000023]  [<ffffffffa03c7470>] ? read_dirty_endio+0x60/0x60 [bcache]
[  +0.000005]  [<ffffffff81516239>] schedule+0x29/0x70
[  +0.000006]  [<ffffffff8108358d>] kthread+0xad/0xf0
[  +0.000005]  [<ffffffff810834e0>] ? kthread_create_on_node+0x180/0x180
[  +0.000005]  [<ffffffff81521abc>] ret_from_fork+0x7c/0xb0
[  +0.000005]  [<ffffffff810834e0>] ? kthread_create_on_node+0x180/0x180

That's just sad to see how unstable was/is bcache sub system and I still
don't understand why it was not marked as experimental.

3.12 was/is buggy when used with writeback mode, and I just had to live
with cache-through. I tried to get some helps (and others too) but no
answers.

I read there were issue with 3.13, so I delayed my kernel upgrade as far
I could due to this. I was hoping that issues were fixed in 3.13.x
stable tree but apparently not.

Hopefully this one will not be ignored.

Francis - I've found it helps if you add all the relevant addresses
mentioned in https://www.kernel.org/doc/linux/MAINTAINERS . For this
mail I'm going to explicitly CC Kent to help this get noticed.
Additionally do you also see this problem with 3.14?

Sorry 3.14 is not available yet on my distro.

Thanks