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Date:   Thu, 18 Aug 2022 09:03:15 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     Chris Murphy <lists@colorremedies.com>
Cc:     Nikolay Borisov <nborisov@suse.com>, Jens Axboe <axboe@kernel.dk>,
        Jan Kara <jack@suse.cz>,
        Paolo Valente <paolo.valente@linaro.org>,
        Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
        Linux-RAID <linux-raid@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Josef Bacik <josef@toxicpanda.com>
Subject: Re: stalling IO regression since linux 5.12, through 5.18
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On Wed, Aug 17, 2022 at 12:34:42PM -0400, Chris Murphy wrote:
> 
> 
> On Wed, Aug 17, 2022, at 11:34 AM, Ming Lei wrote:
> 
> > From the 2nd log of blockdebugfs-all.txt, still not see any in-flight IO on
> > request based block devices, but sda is _not_ included in this log, and
> > only sdi, sdg and sdf are collected, is that expected?
> 
> While the problem was happening I did
> 
> cd /sys/kernel/debug/block
> find . -type f -exec grep -aH . {} \;
> 
> The file has the nodes out of order, but I don't know enough about the interface to see if there are things that are missing, or what it means.
> 
> 
> > BTW, all request based block devices should be observed in blk-mq debugfs.
> 
> /sys/kernel/debug/block contains
> 
> drwxr-xr-x.  2 root root 0 Aug 17 15:20 md0
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sda
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdb
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdc
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdd
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sde
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdf
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdg
> drwxr-xr-x. 51 root root 0 Aug 17 15:20 sdh
> drwxr-xr-x.  4 root root 0 Aug 17 15:20 sdi
> drwxr-xr-x.  2 root root 0 Aug 17 15:20 zram0

OK, so lots of devices are missed in your log, and the following command
is supposed to work for collecting log from all block device's debugfs:

(cd /sys/kernel/debug/block/ && find . -type f -exec grep -aH . {} \;)


Thanks,
Ming