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

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Message-ID: <20240126212150.4b56ae05@nvm>
Date: Fri, 26 Jan 2024 21:21:50 +0500
From: Roman Mamedov <rm@...anrm.net>
To: Carlos Carvalho <carlos@...ica.ufpr.br>
Cc: Dan Moulding <dan@...m.net>, junxiao.bi@...cle.com,
 gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
 linux-raid@...r.kernel.org, regressions@...ts.linux.dev, song@...nel.org,
 stable@...r.kernel.org, yukuai1@...weicloud.com
Subject: Re: [REGRESSION] 6.7.1: md: raid5 hang and unresponsive system;
 successfully bisected

On Fri, 26 Jan 2024 00:30:46 -0300
Carlos Carvalho <carlos@...ica.ufpr.br> wrote:

> Dan Moulding (dan@...m.net) wrote on Thu, Jan 25, 2024 at 05:31:30PM -03:
> > I then created an ext4 file system on the "data" volume, mounted it, and used
> > "dd" to copy 1MiB blocks from /dev/urandom to a file on the "data" file
> > system, and just let it run. Eventually "dd" hangs and top shows that
> > md0_raid5 is using 100% CPU.
> 
> It's known that ext4 has these symptoms with parity raid. To make sure it's a
> raid problem you should try another filesystem or remount it with stripe=0.

If Ext4 wouldn't work properly on parity RAID, then it is a bug that should be
tracked down and fixed, not worked around by using a different FS. I am in
disbelief you are seriously suggesting that, and to be honest really doubt
there is any such high-profile "known" issue that stays unfixed and is just
commonly worked around.

-- 
With respect,
Roman