From: Fabiano Rosas <farosas@suse.de>
To: Peter Xu <peterx@redhat.com>, qemu-devel@nongnu.org
Cc: peterx@redhat.com, qemu-block@nongnu.org,
"Vladimir Sementsov-Ogievskiy" <vsementsov@yandex-team.ru>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Andrey Drobyshev" <andrey.drobyshev@virtuozzo.com>,
"Eric Blake" <eblake@redhat.com>,
"Dr . David Alan Gilbert" <dave@treblig.org>,
"Kevin Wolf" <kwolf@redhat.com>,
"Daniel P . Berrangé" <berrange@redhat.com>
Subject: Re: [PATCH v2 5/6] migration/block: Fix possible race with block_inactive
Date: Mon, 16 Dec 2024 12:18:09 -0300 [thread overview]
Message-ID: <87y10fwtam.fsf@suse.de> (raw)
In-Reply-To: <20241206230838.1111496-6-peterx@redhat.com>
Peter Xu <peterx@redhat.com> writes:
> Src QEMU sets block_inactive=true very early before the invalidation takes
> place. It means if something wrong happened during setting the flag but
> before reaching qemu_savevm_state_complete_precopy_non_iterable() where it
> did the invalidation work, it'll make block_inactive flag inconsistent.
>
> For example, think about when qemu_savevm_state_complete_precopy_iterable()
> can fail: it will have block_inactive set to true even if all block drives
> are active.
>
> Fix that by only update the flag after the invalidation is done.
>
> No Fixes for any commit, because it's not an issue if bdrv_activate_all()
> is re-entrant upon all-active disks - false positive block_inactive can
> bring nothing more than "trying to active the blocks but they're already
> active". However let's still do it right to avoid the inconsistent flag
> v.s. reality.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
next prev parent reply other threads:[~2024-12-16 15:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-06 23:08 [PATCH v2 0/6] migration/block: disk activation rewrite Peter Xu
2024-12-06 23:08 ` [PATCH v2 1/6] migration: Add helper to get target runstate Peter Xu
2024-12-06 23:08 ` [PATCH v2 2/6] qmp/cont: Only activate disks if migration completed Peter Xu
2024-12-16 15:10 ` Fabiano Rosas
2024-12-06 23:08 ` [PATCH v2 3/6] migration/block: Make late-block-active the default Peter Xu
2024-12-16 15:16 ` Fabiano Rosas
2024-12-06 23:08 ` [PATCH v2 4/6] migration/block: Apply late-block-active behavior to postcopy Peter Xu
2024-12-16 15:17 ` Fabiano Rosas
2024-12-06 23:08 ` [PATCH v2 5/6] migration/block: Fix possible race with block_inactive Peter Xu
2024-12-16 15:18 ` Fabiano Rosas [this message]
2024-12-06 23:08 ` [PATCH v2 6/6] migration/block: Rewrite disk activation Peter Xu
2024-12-16 15:58 ` Fabiano Rosas
2024-12-16 18:33 ` Peter Xu
2024-12-17 15:26 ` [PATCH v2 0/6] migration/block: disk activation rewrite Fabiano Rosas
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