lkml.org 
[lkml]   [2016]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.16.y-ckt 093/180] virtio_balloon: fix race by fill and leak
    Date
    3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: Minchan Kim <minchan@kernel.org>

    commit f68b992bbb474641881932c61c92dcfa6f5b3689 upstream.

    During my compaction-related stuff, I encountered a bug
    with ballooning.

    With repeated inflating and deflating cycle, guest memory(
    ie, cat /proc/meminfo | grep MemTotal) is decreased and
    couldn't be recovered.

    The reason is balloon_lock doesn't cover release_pages_balloon
    so struct virtio_balloon fields could be overwritten by race
    of fill_balloon(e,g, vb->*pfns could be critical).

    This patch fixes it in my test.

    Signed-off-by: Minchan Kim <minchan@kernel.org>
    Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    [ luis: backported to 3.16: adjusted context ]
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    drivers/virtio/virtio_balloon.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
    index 25ebe8eecdb7..eb35e3fa984a 100644
    --- a/drivers/virtio/virtio_balloon.c
    +++ b/drivers/virtio/virtio_balloon.c
    @@ -193,8 +193,8 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
    */
    if (vb->num_pfns != 0)
    tell_host(vb, vb->deflate_vq);
    - mutex_unlock(&vb->balloon_lock);
    release_pages_by_pfn(vb->pfns, vb->num_pfns);
    + mutex_unlock(&vb->balloon_lock);
    }

    static inline void update_stat(struct virtio_balloon *vb, int idx,
    \
     
     \ /
      Last update: 2016-02-04 01:01    [W:4.116 / U:0.048 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site