From: no-reply@sashiko.virtuozzo.com
To: Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>,
Konstantin Khorenko <khorenko@virtuozzo.com>,
Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>,
Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 1/2] ms/vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc
Date: Wed, 14 Oct 2026 17:34:54 +0000 [thread overview]
Message-ID: <010701a13b7b3bfb-3de6605a-d3c1-4870-8cb2-95404a4a8f5f-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261014-b4-prep-khorenko-vstor-149847-6-vfio-exec-ms-backports-v1-1-07b4e541d4ec@virtuozzo.com>
> From: Junrui Luo <moonafterrain@outlook.com>
>
> vfio_mig_get_next_state() walks vfio_from_fsm_table[] one step at a time,
> looping to skip optional states the device does not support until
> *next_fsm is supported. A blocked transition is encoded as
> VFIO_DEVICE_STATE_ERROR, which the trailing return reports as -EINVAL.
>
> The skip loop does not account for the ERROR sentinel.
> state_flags_table[ERROR] is ~0U and vfio_from_fsm_table[ERROR][*] is
> ERROR, so once *next_fsm becomes ERROR the loop condition stays true and
> *next_fsm never changes. The blocked arcs STOP_COPY -> PRE_COPY and
> STOP_COPY -> PRE_COPY_P2P map to ERROR yet pass the support check on a
> precopy-capable device, causing the loop to spin forever while holding
> the driver state mutex. This can result in a soft lockup, and a panic
> with softlockup_panic set.
> [ ... ]
> https://virtuozzo.atlassian.net/browse/VSTOR-150235
> Feature: fix ms/vfio
>
> Assisted-by: LLM
> Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261014-b4-prep-khorenko-vstor-149847-6-vfio-exec-ms-backports-v1-0-07b4e541d4ec@virtuozzo.com?part=1
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next prev parent reply other threads:[~2026-10-14 17:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 17:16 [Devel] [PATCH hci-8.1 0/2] vfio, exec: two mainline fixes that Oracle carries Konstantin Khorenko
2026-10-14 17:16 ` [Devel] [PATCH hci-8.1 1/2] ms/vfio: prevent infinite loop in vfio_mig_get_next_state() on blocked arc Konstantin Khorenko
2026-10-14 17:34 ` no-reply [this message]
2026-10-14 17:16 ` [Devel] [PATCH hci-8.1 2/2] ms/exec: do_close_on_exec() before taking exec_update_lock Konstantin Khorenko
2026-10-14 17:35 ` no-reply
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