linux-kernel - Re: commit 762380a "block: add notion of a chunk size for request merging" stops io on btrfs

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Message-ID: <53A0B568.9070700@gmail.com>
Date:	Wed, 18 Jun 2014 00:38:48 +0300
From:	Konstantinos Skarlatos <k.skarlatos@...il.com>
To:	axboe@...com, linux-kernel@...r.kernel.org
CC:	linux-btrfs@...r.kernel.org
Subject: Re: commit 762380a "block: add notion of a chunk size for
 request merging" stops io on btrfs

On 18/6/2014 12:35 πμ, Konstantinos Skarlatos wrote:
> Hi all,
> with 3.16-rc1  rsync stops writing to my btrfs filesystem and stays at 
> a D+ state.
> git bisect showed that the problematic commit is:
>
> 762380ad9322951cea4ce9d24864265f9c66a916 is the first bad commit
> commit 762380ad9322951cea4ce9d24864265f9c66a916
> Author: Jens Axboe <axboe@...com>
> Date:   Thu Jun 5 13:38:39 2014 -0600
>
>     block: add notion of a chunk size for request merging
>
>     Some drivers have different limits on what size a request should
>     optimally be, depending on the offset of the request. Similar to
>     dividing a device into chunks. Add a setting that allows the driver
>     to inform the block layer of such a chunk size. The block layer will
>     then prevent merging across the chunks.
>
>     This is needed to optimally support NVMe with a non-zero stripe size.
>
>     Signed-off-by: Jens Axboe <axboe@...com>
>
> sysrq w gives:
Just ran another  echo w > /proc/sysrq-trigger, attaching output.

>
> [ 3287.169569] SysRq : Show Blocked State
> [ 3287.169655]   task                        PC stack   pid father
> [ 3287.169675] rsync           D 0000000000000001     0   626 613 
> 0x00000000
> [ 3287.169685]  ffff8802037c7d08 0000000000000082 ffff8800cf2e7010 
> 0000000000014500
> [ 3287.169693]  ffff8802037c7fd8 0000000000014500 ffff8800cf2e7010 
> ffff8802037c7c98
> [ 3287.169700]  0000000000000292 0000000000000292 ffff8802037c7c50 
> ffff8802037c7c50
> [ 3287.169706] Call Trace:
> [ 3287.169722]  [<ffffffff814f71d2>] ? do_page_fault+0x22/0x30
> [ 3287.169733]  [<ffffffff8101cd89>] ? read_tsc+0x9/0x20
> [ 3287.169743]  [<ffffffff811379d0>] ? sleep_on_page+0x20/0x20
> [ 3287.169749]  [<ffffffff814eff29>] schedule+0x29/0x70
> [ 3287.169756]  [<ffffffff814f0214>] io_schedule+0x94/0xf0
> [ 3287.169763]  [<ffffffff811379de>] sleep_on_page_killable+0xe/0x50
> [ 3287.169770]  [<ffffffff814f0748>] __wait_on_bit_lock+0x48/0xb0
> [ 3287.169777]  [<ffffffff8128c753>] ? radix_tree_lookup_slot+0x13/0x30
> [ 3287.169785]  [<ffffffff81137b7a>] __lock_page_killable+0x6a/0x70
> [ 3287.169792]  [<ffffffff810acec0>] ? autoremove_wake_function+0x40/0x40
> [ 3287.169799]  [<ffffffff811398c8>] generic_file_aio_read+0x458/0x6a0
> [ 3287.169808]  [<ffffffff811ab63a>] do_sync_read+0x5a/0x90
> [ 3287.169816]  [<ffffffff811abc47>] vfs_read+0x97/0x160
> [ 3287.169823]  [<ffffffff811ac886>] SyS_read+0x46/0xc0
> [ 3287.169831]  [<ffffffff814fb969>] system_call_fastpath+0x16/0x1b
>
> $ btrfs filesystem show /storage/btrfs
> Label: none  uuid: bde3c349-9e08-45bb-8517-b9a6dda81e88
>         Total devices 6 FS bytes used 8.58TiB
>         devid    1 size 3.64TiB used 3.02TiB path /dev/sdf
>         devid    2 size 1.82TiB used 1.20TiB path /dev/sda
>         devid    3 size 1.82TiB used 1.20TiB path /dev/sdb
>         devid    4 size 1.82TiB used 1.20TiB path /dev/sdc
>         devid    5 size 1.82TiB used 1.20TiB path /dev/sdd
>         devid    6 size 1.82TiB used 1.20TiB path /dev/sdh
>
> Btrfs v3.14.2-dirty
>
> $ btrfs fi df /storage/btrfs
> Data, single: total=8.89TiB, used=8.51TiB
> System, RAID1: total=32.00MiB, used=992.00KiB
> Metadata, RAID1: total=69.00GiB, used=67.83GiB
> unknown, single: total=512.00MiB, used=0.00
>
> full dmesg attached
> Please CC me if replying on LKML, as I am not subscribed there


View attachment "dmesg_blocked2.txt" of type "text/plain" (55983 bytes)