On Thu, Sep 09 2010 at 4:30pm -0400, Ryan Harper <ryanh@xxxxxxxxxx> wrote: > * Mike Snitzer <snitzer@xxxxxxxxxx> [2010-09-09 15:15]: > > On Thu, Sep 09 2010 at 3:43pm -0400, > > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > > > > > Interestingly, just this loop: > > > > > > while true ; do cat /sys/block/vda/serial && date && sleep 1 ; done > > > Thu Sep 9 15:29:30 EDT 2010 > > > ... > > > Thu Sep 9 15:31:19 EDT 2010 > > > > > > caused the following hang: > > ... > > > So it seems like the virtio requests aren't being properly cleaned up? > > > > Yeap, here is the result with the attached debug patch that Vivek wrote > > last week to help chase this issue (which adds 'nr_requests_used'). We > > thought the mpath device might be leaking requests; concern for other > > devices wasn't on our radar: > > > > # cat /sys/block/vda/queue/nr_requests > > 128 > > > > # while true ; do cat /sys/block/vda/queue/nr_requests_used && cat /sys/block/vda/serial && date && sleep 1 ; done > > 10 > > Thu Sep 9 16:04:40 EDT 2010 > > 11 > > Thu Sep 9 16:04:41 EDT 2010 > > ... > > Thu Sep 9 16:06:38 EDT 2010 > > 127 > > Thu Sep 9 16:06:39 EDT 2010 > > 128 > > > > I'll have a quick look at the virtio-blk code to see if I can spot where > > the request isn't getting cleaned up. But I welcome others to have a > > look too (I've already spent entirely way to much time on this issue). > > The qemu on the host isn't new enough to handle the request. This > serial attribute should have had a feature bit with it (it did at one > point in one of the previous forms of the virtio-blk serial patch > series, but it isn't present now) so we don't expose the attribute > unless backend can handle the request type. Be that as it may, it doesn't change the fact that the request created in virtblk_get_id (via blk_make_request) isn't being properly cleaned up. > For immediate relief, it's probably easiest to revert the kernel-side > commit (or comment out the device_create_file() call after add_disk() in > virtblk_probe(). This patch fixes the issue for me; Rusty and/or Christoph please review/advise. From: Mike Snitzer <snitzer@xxxxxxxxxx> Subject: virtio-blk: put request that was created to retrieve the device id Must drop reference taken by blk_make_request(). Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- drivers/block/virtio_blk.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 1260628..831e75c 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -199,6 +199,7 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) struct virtio_blk *vblk = disk->private_data; struct request *req; struct bio *bio; + int err; bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL); @@ -212,7 +213,10 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) } req->cmd_type = REQ_TYPE_SPECIAL; - return blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); + err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); + blk_put_request(req); + + return err; } static int virtblk_locked_ioctl(struct block_device *bdev, fmode_t mode, -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
