From: no-reply@sashiko.virtuozzo.com
To: "Denis V. Lunev" <den@openvz.org>, andrey.zhadchenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 2/2] dm-ploop: fix flip_upper_deltas walking past the BAT of the lower delta
Date: Wed, 4 Nov 2026 21:50:44 +0000 [thread overview]
Message-ID: <010701a1a88b01db-3fdf2d48-a151-41b9-a478-971f40d906fc-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261104214635.2063009-3-den@openvz.org>
> From: Denis V. Lunev <den@openvz.org>
>
> ploop_check_delta_before_flip() walks the live BAT pages together with
> the BAT pages of the lower delta, and means to stop at the page that
> holds the last entry of the lower delta. It takes that entry from i
> after the scan of the page, when i is already one past end, so the stop
> never matches. Once the live BAT has more pages than the lower delta, as
> after a grow of the device, the walk runs off the md tree of the lower
> delta and dereferences a NULL page: the flip oopses. The reverse merge
> of the ploop library grows the lower delta to the size of the top before
> it flips, so only a flip outside the library gets there.
>
> Take the last entry of the page from end.
>
> Fixes: 6ddad5a4d226 ("dm-ploop: Add ploop target driver")
> https://virtuozzo.atlassian.net/browse/VSTOR-153445
> Feature: dm-ploop: ploop target driver
> Signed-off-by: Denis V. Lunev <den@openvz.org>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261104214635.2063009-1-den@openvz.org?part=2
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prev parent reply other threads:[~2026-11-04 21:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 21:46 [Devel] [PATCH hci-8.1 0/2] dm-ploop: fix flip_upper_deltas panicking the host in its pre-flip check Denis V. Lunev
2026-11-04 21:46 ` [Devel] [PATCH hci-8.1 1/2] dm-ploop: fix flip_upper_deltas returning with two md_locks held Denis V. Lunev
2026-11-04 21:50 ` no-reply
2026-11-04 21:46 ` [Devel] [PATCH hci-8.1 2/2] dm-ploop: fix flip_upper_deltas walking past the BAT of the lower delta Denis V. Lunev
2026-11-04 21:50 ` no-reply [this message]
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