From: no-reply@sashiko.virtuozzo.com
To: Alexander Ivanov <alexander.ivanov@virtuozzo.com>,
andrey.zhadchenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v2] dm table: don't inherit live table's type for request-based tables
Date: Tue, 20 Oct 2026 07:57:04 +0000 [thread overview]
Message-ID: <010701a158505cb8-3310ecd6-b2d6-4e88-9de1-ea109628f0bd-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261020075243.1283345-1-alexander.ivanov@virtuozzo.com>
> A request-based table without devices inherits the live table's type
> in dm_table_determine_type(). Since commit 6936c12cf809 ("dm table: fix
> 'all_blk_mq' inconsistency when an empty table is loaded") this
> includes bio-based types, although the inheritance was meant to pick a
> variant of the request-based type, and only one is left now. So a
> request-based table loaded over a bio-based device becomes bio-based,
> which its target cannot serve.
>
> dm-qcow2 and dm-ploop open their images by fd and never call
> dm_get_device(). Loaded over a bio-based device they have no ->map, and
> the first bio calls a NULL ->map from __map_bio():
>
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> RIP: 0010:0x0
> __map_bio+0x197/0x1c0 [dm_mod]
> [ ... ]
> "can't change device type", as it does for request-based tables with
> devices.
>
> https://virtuozzo.atlassian.net/browse/VSTOR-150573
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261020075243.1283345-1-alexander.ivanov@virtuozzo.com?part=1
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prev parent reply other threads:[~2026-10-20 10:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-20 7:52 Alexander Ivanov
2026-10-20 7:57 ` no-reply [this message]
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