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Re: [PATCH 2/3] migration: Don't do migrate cleanup if during postcopy r
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH 2/3] migration: Don't do migrate cleanup if during postcopy resume |
Date: |
Mon, 12 Jul 2021 19:33:40 +0100 |
User-agent: |
Mutt/2.0.7 (2021-05-04) |
* Peter Xu (peterx@redhat.com) wrote:
> Below process could crash qemu with postcopy recovery:
>
> 1. (hmp) migrate -d ..
> 2. (hmp) migrate_start_postcopy
> 3. [network down, postcopy paused]
> 4. (hmp) migrate -r $WRONG_PORT
> when try the recover on an invalid $WRONG_PORT, cleanup_bh will be
> cleared
> 5. (hmp) migrate -r $RIGHT_PORT
> [qemu crash on assert(cleanup_bh)]
>
> The thing is we shouldn't cleanup if it's postcopy resume; the error is set
> mostly because the channel is wrong, so we return directly waiting for the
> user
> to retry.
>
> migrate_fd_cleanup() should only be called when migration is cancelled or
> completed.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> migration/migration.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 8786104c9a..bb1edf862a 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -3975,7 +3975,18 @@ void migrate_fd_connect(MigrationState *s, Error
> *error_in)
> }
> if (error_in) {
> migrate_fd_error(s, error_in);
> - migrate_fd_cleanup(s);
> + if (resume) {
> + /*
> + * Don't do cleanup for resume if channel is invalid, but only
> dump
> + * the error. We wait for another channel connect from the user.
> + * The error_report still gives HMP user a hint on what failed.
> + * It's normally done in migrate_fd_cleanup(), but call it here
> + * explicitly.
> + */
> + error_report_err(error_copy(s->error));
> + } else {
> + migrate_fd_cleanup(s);
> + }
> return;
> }
>
> --
> 2.31.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK