From: "Marc-André Lureau" <marcandre.lureau@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>,
Juan Quintela <quintela@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
Leonardo Bras Soares Passos <lsoaresp@redhat.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH 2/2] dump-guest-memory: Block live migration
Date: Tue, 24 Aug 2021 22:04:19 +0400 [thread overview]
Message-ID: <CAMxuvawNsaL66nTiWaQa72D_kDzRPj_-AWnof4att6ghcBSZkQ@mail.gmail.com> (raw)
In-Reply-To: <20210824152721.79747-3-peterx@redhat.com>
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Hi
On Tue, Aug 24, 2021 at 7:27 PM Peter Xu <peterx@redhat.com> wrote:
> Both dump-guest-memory and live migration caches vm state at the beginning.
> Either of them entering the other one will cause race on the vm state, and
> even
> more severe on that (please refer to the crash report in the bug link).
>
> Let's block live migration in dump-guest-memory, and that'll also block
> dump-guest-memory if it detected that we're during a live migration.
>
How does it detect that migration is in progress?
Otherwise, it looks reasonable to me.
> Side note: migrate_del_blocker() can be called even if the blocker is not
> inserted yet, so it's safe to unconditionally delete that blocker in
> dump_cleanup (g_slist_remove allows no-entry-found case).
>
> Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1996609
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> dump/dump.c | 20 +++++++++++++++-----
> include/sysemu/dump.h | 1 +
> 2 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/dump/dump.c b/dump/dump.c
> index ab625909f3..7996d7a6c5 100644
> --- a/dump/dump.c
> +++ b/dump/dump.c
> @@ -29,6 +29,7 @@
> #include "qemu/error-report.h"
> #include "qemu/main-loop.h"
> #include "hw/misc/vmcoreinfo.h"
> +#include "migration/blocker.h"
>
> #ifdef TARGET_X86_64
> #include "win_dump.h"
> @@ -101,6 +102,7 @@ static int dump_cleanup(DumpState *s)
> qemu_mutex_unlock_iothread();
> }
> }
> + migrate_del_blocker(s->dump_migration_blocker);
>
> return 0;
> }
> @@ -1857,6 +1859,19 @@ static void dump_init(DumpState *s, int fd, bool
> has_format,
> }
> }
>
> + if (!s->dump_migration_blocker) {
> + error_setg(&s->dump_migration_blocker,
> + "Live migration disabled: dump-guest-memory in
> progress");
> + }
> +
> + /*
> + * Allows even for -only-migratable, but forbid migration during the
> + * process of dump guest memory.
> + */
> + if (migrate_add_blocker_internal(s->dump_migration_blocker, errp)) {
> + goto cleanup;
> + }
> +
> return;
>
> cleanup:
> @@ -1927,11 +1942,6 @@ void qmp_dump_guest_memory(bool paging, const char
> *file,
> Error *local_err = NULL;
> bool detach_p = false;
>
> - if (runstate_check(RUN_STATE_INMIGRATE)) {
> - error_setg(errp, "Dump not allowed during incoming migration.");
> - return;
> - }
> -
> /* if there is a dump in background, we should wait until the dump
> * finished */
> if (dump_in_progress()) {
> diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
> index 250143cb5a..7b619c2a43 100644
> --- a/include/sysemu/dump.h
> +++ b/include/sysemu/dump.h
> @@ -195,6 +195,7 @@ typedef struct DumpState {
> * finished. */
> uint8_t *guest_note; /* ELF note content */
> size_t guest_note_size;
> + Error *dump_migration_blocker; /* Blocker for live migration */
> } DumpState;
>
> uint16_t cpu_to_dump16(DumpState *s, uint16_t val);
> --
> 2.31.1
>
>
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next prev parent reply other threads:[~2021-08-24 18:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 15:27 [PATCH 0/2] dump-guest-memory: Add blocker for migration Peter Xu
2021-08-24 15:27 ` [PATCH 1/2] migration: Add migrate_add_blocker_internal() Peter Xu
2021-08-24 18:04 ` Marc-André Lureau
2021-08-25 8:04 ` Juan Quintela
2021-08-24 15:27 ` [PATCH 2/2] dump-guest-memory: Block live migration Peter Xu
2021-08-24 18:04 ` Marc-André Lureau [this message]
2021-08-24 19:39 ` Peter Xu
2021-08-25 7:36 ` Marc-André Lureau
2021-08-25 20:48 ` Peter Xu
2021-08-25 7:54 ` [PATCH 0/2] dump-guest-memory: Add blocker for migration Markus Armbruster
2021-08-25 21:32 ` Peter Xu
2021-09-01 11:35 ` Markus Armbruster
2021-09-03 16:08 ` Peter Xu
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