linux-kernel - Re: RCU stalls and GPFs in ceph/netfs

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Message-ID: <CAKPOu+8s3f8WdhyEPqfXMBrbE+j4OqzGXCUv=rTTmWzbWvr-Tg@mail.gmail.com>
Date: Mon, 29 Jul 2024 11:18:42 +0200
From: Max Kellermann <max.kellermann@...os.com>
To: David Howells <dhowells@...hat.com>
Cc: Jeff Layton <jlayton@...nel.org>, netfs@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	ceph-devel@...r.kernel.org
Subject: Re: RCU stalls and GPFs in ceph/netfs

On Sun, Jul 28, 2024 at 12:49 PM Max Kellermann
<max.kellermann@...os.com> wrote:
> in the last few days, I have been chasing a 6.10 regression. After
> updating one of our servers from 6.9.10 to 6.10.1, I found various
> problems that may or may not be caused by the same code change
> (abbreviated):

Today, I gave this another try and it turned out to be a simple
leftover folio_end_private_2() call. It was really caused by commit
ae678317b95e ("netfs: Remove deprecated use of PG_private_2 as a
second writeback flag"), after all.

I posted two candidate patches which both fix this bug;

Minimal fix: https://lore.kernel.org/lkml/20240729090639.852732-1-max.kellermann@ionos.com/
Fix which removes a bunch of obsolete code:
https://lore.kernel.org/lkml/20240729091532.855688-1-max.kellermann@ionos.com/

You decide which one you prefer.

Max