Re: [REGRESSION] 6.7.1: md: raid5 hang and unresponsive system; successfully bisected

[Yu Kuai]

Hi,

在 2024/01/31 9:26, Song Liu 写道:
> > Scenario:
> > 1. Create raid10:
> > mdadm --create /dev/md/r10d4s128-15_A --level=10 --chunk=128
> > --raid-devices=4 /dev/nvme6n1 /dev/nvme2n1 /dev/nvme3n1 /dev/nvme0n1
> > --size=7864320 --run
> > 2. Create FS
> > mkfs.ext4 /dev/md/r10d4s128-15_A
> > 3. Set faulty one raid member:
> > mdadm --set-faulty /dev/md/r10d4s128-15_A /dev/nvme3n1
> With a failed drive, md_thread calls md_check_recovery() and kicks
> off mddev->sync_work, which is md_start_sync().
> md_check_recovery() also sets MD_RECOVERY_RUNNING.
>
> md_start_sync() calls mddev_suspend() and waits for
> mddev->active_io to become zero.
>
> > 4. Stop raid devies:
> > mdadm -Ss
> This command calls stop_sync_thread() and waits for
> MD_RECOVERY_RUNNING to be cleared.
>
> Given we need a working file system to reproduce the issue, I
> suspect the problem comes from active_io.

I'll look into this. But I don't understand the root cause yet.
Who grab the 'active_io' and why doesn't release it?

Thanks,
Kuai

> Yu Kuai, I guess we missed this case in the recent refactoring.
> I don't have a good idea to fix this. Please also take a look into
> this.