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From: Kevin Wolf <kwolf@redhat.com>
To: Hanna Czenczek <hreitz@redhat.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org,
	Peter Lieven <pl@dlhnet.de>,
	qemu-stable@nongnu.org
Subject: Re: [PATCH] block/nfs: Do not enter coroutine from CB
Date: Fri, 6 Mar 2026 14:32:00 +0100	[thread overview]
Message-ID: <aarXUASFcw6ecWlb@redhat.com> (raw)
In-Reply-To: <20260102153246.154207-1-hreitz@redhat.com>

Am 02.01.2026 um 16:32 hat Hanna Czenczek geschrieben:
> The reasoning I gave for why it would be safe to call aio_co_wake()
> despite holding the mutex was wrong: It is true that the current request
> will not re-acquire the mutex, but a subsequent request in the same
> coroutine can.  Because the mutex is a non-coroutine mutex, this will
> result in a deadlock.
> 
> Therefore, we must either not enter the coroutine here (only scheduling
> it), or release the mutex around aio_co_wake().  I opt for the former,
> as it is the behavior prior to the offending commit, and so seems safe
> to do.
> 
> Fixes: deb35c129b859b9bec70fd42f856a0b7c1dc6e61
>        ("nfs: Run co BH CB in the coroutine’s AioContext")
> Buglink: https://gitlab.com/qemu-project/qemu/-/issues/2622#note_2965097035
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Hanna Czenczek <hreitz@redhat.com>

Thanks, applied to the block branch.

Kevin



      reply	other threads:[~2026-03-06 13:32 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-02 15:32 [PATCH] block/nfs: Do not enter coroutine from CB Hanna Czenczek
2026-03-06 13:32 ` Kevin Wolf [this message]

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