linux-kernel - Re: [PATCH] ceph: fix deadlock bugs by making iput() calls asynchronous

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Message-ID: <CAKPOu+9io3n=PzwFPPgmGSE0moe3KDbyp7MXmwx=xU=Hsvqrvw@mail.gmail.com>
Date: Thu, 18 Sep 2025 06:43:15 +0200
From: Max Kellermann <max.kellermann@...os.com>
To: Dave Chinner <david@...morbit.com>
Cc: xiubli@...hat.com, idryomov@...il.com, amarkuze@...hat.com, 
	ceph-devel@...r.kernel.org, netfs@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	Mateusz Guzik <mjguzik@...il.com>, stable@...r.kernel.org
Subject: Re: [PATCH] ceph: fix deadlock bugs by making iput() calls asynchronous

On Thu, Sep 18, 2025 at 12:51 AM Dave Chinner <david@...morbit.com> wrote:
> - wait for Josef to finish his inode refcount rework patchset that
>   gets rid of this whole "writeback doesn't hold an inode reference"
>   problem that is the root cause of this the deadlock.

No, it is necessary to have a minimal fix that is eligible for stable backports.

Of course, my patch is a kludge; this problem is much larger and a
general, global solution should be preferred. But my patch is minimal,
easy to understand, doesn't add overhead and piggybacks on an existing
Ceph feature (per-inode work) that is considered mature and stable.
It can be backported easily to 6.12 and 6.6 (with minor conflicts due
to renamed netfs functions in adjacent lines).