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author | David Hildenbrand <david@redhat.com> | 2020-06-29 10:06:15 +0200 |
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committer | Michael S. Tsirkin <mst@redhat.com> | 2020-07-02 05:54:59 -0400 |
commit | dd8eeb9671fc881e613008bd20035b85fe45383d (patch) | |
tree | 65e87cb3516f0248e2156d5c1102cd22df5f5e46 /hw/virtio | |
parent | 0d935ffd66154a2aa3af3e49bcffd832a8bb53e5 (diff) | |
download | qemu-dd8eeb9671fc881e613008bd20035b85fe45383d.zip qemu-dd8eeb9671fc881e613008bd20035b85fe45383d.tar.gz qemu-dd8eeb9671fc881e613008bd20035b85fe45383d.tar.bz2 |
virtio-balloon: always indicate S_DONE when migration fails
If something goes wrong during precopy, before stopping the VM, we will
never send a S_DONE indication to the VM, resulting in the hinted pages
not getting released to be used by the guest OS (e.g., Linux).
Easy to reproduce:
1. Start migration (e.g., HMP "migrate -d 'exec:gzip -c > STATEFILE.gz'")
2. Cancel migration (e.g., HMP "migrate_cancel")
3. Oberve in the guest (e.g., cat /proc/meminfo) that there is basically
no free memory left.
While at it, add similar locking to virtio_balloon_free_page_done() as
done in virtio_balloon_free_page_stop. Locking is still weird, but that
has to be sorted out separately.
There is nothing to do in the PRECOPY_NOTIFY_COMPLETE case. Add some
comments regarding S_DONE handling.
Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200629080615.26022-1-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/virtio')
-rw-r--r-- | hw/virtio/virtio-balloon.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 10507b2..8a84718 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -628,8 +628,13 @@ static void virtio_balloon_free_page_done(VirtIOBalloon *s) { VirtIODevice *vdev = VIRTIO_DEVICE(s); - s->free_page_report_status = FREE_PAGE_REPORT_S_DONE; - virtio_notify_config(vdev); + if (s->free_page_report_status != FREE_PAGE_REPORT_S_DONE) { + /* See virtio_balloon_free_page_stop() */ + qemu_mutex_lock(&s->free_page_lock); + s->free_page_report_status = FREE_PAGE_REPORT_S_DONE; + qemu_mutex_unlock(&s->free_page_lock); + virtio_notify_config(vdev); + } } static int @@ -653,17 +658,26 @@ virtio_balloon_free_page_report_notify(NotifierWithReturn *n, void *data) case PRECOPY_NOTIFY_SETUP: precopy_enable_free_page_optimization(); break; - case PRECOPY_NOTIFY_COMPLETE: - case PRECOPY_NOTIFY_CLEANUP: case PRECOPY_NOTIFY_BEFORE_BITMAP_SYNC: virtio_balloon_free_page_stop(dev); break; case PRECOPY_NOTIFY_AFTER_BITMAP_SYNC: if (vdev->vm_running) { virtio_balloon_free_page_start(dev); - } else { - virtio_balloon_free_page_done(dev); + break; } + /* + * Set S_DONE before migrating the vmstate, so the guest will reuse + * all hinted pages once running on the destination. Fall through. + */ + case PRECOPY_NOTIFY_CLEANUP: + /* + * Especially, if something goes wrong during precopy or if migration + * is canceled, we have to properly communicate S_DONE to the VM. + */ + virtio_balloon_free_page_done(dev); + break; + case PRECOPY_NOTIFY_COMPLETE: break; default: virtio_error(vdev, "%s: %d reason unknown", __func__, pnd->reason); |