From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org
Subject: Re: [bug?] blk_queue_may_bounce() has the comparison max_low_pfn and max_pfn wrong way
Date: Sun, 30 Oct 2022 08:50:32 +0100 [thread overview]
Message-ID: <20221030075032.GC4214@lst.de> (raw)
In-Reply-To: <Y11YuS3kiOWoOjuI@ZenIV>
On Sat, Oct 29, 2022 at 05:45:45PM +0100, Al Viro wrote:
> completion (in NULL_Q_BIO case, at least). What happens if request
> gets split and split-off part finishes first with an error? AFAICS,
> its ->bi_status will be copied to parent (original bio, the one that
> covers the tail). Now the IO on the original bio is over as well
> and we hit drivers/block/null_blk/main.c:end_cmd(). Suppose this
> part succeeds; won't we end up overwriting ->bi_status with zero
> and assuming that the entire thing had succeeded, despite the
> (now lost) error on the split-off part?
As a rule of thumb drives should never set bi_status to 0, so null_blk
here has a bug. What is missing everywhere is proper memory barriers,
though.
next prev parent reply other threads:[~2022-10-30 7:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-28 18:02 [bug?] blk_queue_may_bounce() has the comparison max_low_pfn and max_pfn wrong way Al Viro
2022-10-28 18:51 ` Jens Axboe
2022-10-28 19:21 ` Al Viro
2022-10-29 16:45 ` Al Viro
2022-10-30 7:50 ` Christoph Hellwig [this message]
2022-10-30 18:47 ` Al Viro
2022-11-01 11:11 ` Christoph Hellwig
2022-10-30 7:48 ` Christoph Hellwig
2022-10-28 19:14 ` Al Viro
2022-10-30 7:45 ` Christoph Hellwig
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