Re: [HANG 3.13-rc3] blk-mq/virtio: mkfs.ext4 hangs in blk_mq_wait_for_tags

[Ming Lei]

On Tue, Dec 10, 2013 at 6:39 AM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
> Hi Jens,
>
> Another day, another blkmq/virtio problem. Running mkfs.ext4 on a
> sparse 100TB VM file image, it hangs hard while writing superblock
> information:
>
> $ tests/fsmark-50-test-ext4.sh
> mke2fs 1.43-WIP (20-Jun-2013)
> Filesystem label=
> OS type: Linux
> Block size=4096 (log=2)
> Fragment size=4096 (log=2)
> Stride=0 blocks, Stripe width=0 blocks
> 1677721600 inodes, 26843545600 blocks
> 1342177280 blocks (5.00%) reserved for the super user
> First data block=0
> 819200 block groups
> 32768 blocks per group, 32768 fragments per group
> 2048 inodes per group
> Superblock backups stored on blocks:
>         32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
>         4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
>         102400000, 214990848, 512000000, 550731776, 644972544, 1934917632,
>         2560000000, 3855122432, 5804752896, 12800000000, 17414258688
>
> Allocating group tables: done
> Writing inode tables: done
> Creating journal (32768 blocks): done
> Writing superblocks and filesystem accounting information:
>
> It writes a few superblocks, then hangs. Immediately after it stops
> updating that last line, I see this:
>
> root@test4:~# echo w > /proc/sysrq-trigger

It might be helpful to do below and post the result before the sysrq-trigger:

         cat    /sys/class/block/vda/mq/0/tags


Thanks,
-- 
Ming Lei
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