From: Christoph Hellwig <hch@infradead.org>
To: Michael Liang <mliang@purestorage.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blk-mq: always clear rq->bio in blk_complete_request()
Date: Thu, 18 Dec 2025 00:51:14 -0800 [thread overview]
Message-ID: <aUPAgtbWVql9SkoG@infradead.org> (raw)
In-Reply-To: <20251217171853.2648851-1-mliang@purestorage.com>
On Wed, Dec 17, 2025 at 10:18:53AM -0700, Michael Liang wrote:
> Commit ab3e1d3bbab9 ("block: allow end_io based requests in the
> completion batch handling") changed blk_complete_request() so that
> rq->bio and rq->__data_len are only cleared when ->end_io is NULL.
>
> This conditional clearing is incorrect. The block layer guarantees that
> all bios attached to the request are fully completed and released before
> blk_complete_request() is called. Leaving rq->bio pointing to already
> completed bios results in stale pointers that may be reused immediately
> by a bioset allocator.
Passthrough commands keep an extra reference on the bio and need the
pointer to call blk_rq_unmap_user from the completion handler.
next prev parent reply other threads:[~2025-12-18 8:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-17 17:18 Michael Liang
2025-12-18 8:51 ` Christoph Hellwig [this message]
2025-12-18 16:37 ` Michael Liang
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