From: Matthew Wilcox <willy@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
bernd@bsbernd.com, Joanne Koong <joannelkoong@gmail.com>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v2] flex_proportions: Make fprop_new_period() hardirq safe
Date: Wed, 21 Jan 2026 13:43:00 +0000 [thread overview]
Message-ID: <aXDX5IXuvghtyZZU@casper.infradead.org> (raw)
In-Reply-To: <20260121112729.24463-2-jack@suse.cz>
On Wed, Jan 21, 2026 at 12:27:30PM +0100, Jan Kara wrote:
> Bernd has reported a lockdep splat from flexible proportions code that
> is essentially complaining about the following race:
[...]
> Note that a deadlock like this is only possible if the bdi has
> configured maximum fraction of writeout throughput which is very rare
> in general but frequent for example for FUSE bdis. To fix this problem
> we have to make sure write section of the sequence counter is irqsafe.
Ah, that's why we haven't seen it reported before.
> CC: stable@vger.kernel.org
> Fixes: a91befde3503 ("lib/flex_proportions.c: remove local_irq_ops in fprop_new_period()")
> Reported-by: Bernd Schubert <bernd@bsbernd.com>
> Link: https://lore.kernel.org/all/9b845a47-9aee-43dd-99bc-1a82bea00442@bsbernd.com/
> Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
prev parent reply other threads:[~2026-01-21 13:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-21 11:27 [PATCH v2] flex_proportions: Make fprop_new_period() hardirq safe Jan Kara
2026-01-21 13:43 ` Matthew Wilcox [this message]
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