On Tue, Sep 17, 2013 at 10:21:07AM +0300, Michael S. Tsirkin wrote:
> As vhost scsi device struct is large, if the device is
> created on a busy system, kzalloc() might fail, so this patch does a
> fallback to vzalloc().
>
> As vmalloc() adds overhead on data-path, add __GFP_REPEAT
> to kzalloc() flags to do this fallback only when really needed.
>
> Reported-by: Dan Aloni <alonid@xxxxxxxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Asias He <asias@xxxxxxxxxx>
> ---
>
> I put this on my vhost fixes branch, intend to merge for 3.12.
> Dan, could you please confirm this works for you?
>
> drivers/vhost/scsi.c | 41 +++++++++++++++++++++++++++--------------
> 1 file changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
> index 4b79a1f..2c30bb0 100644
> --- a/drivers/vhost/scsi.c
> +++ b/drivers/vhost/scsi.c
> @@ -1373,21 +1373,30 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> return 0;
> }
>
> +static void vhost_scsi_free(struct vhost_scsi *vs)
> +{
> + if (is_vmalloc_addr(vs))
> + vfree(vs);
> + else
> + kfree(vs);
> +}
> +
> static int vhost_scsi_open(struct inode *inode, struct file *f)
> {
> struct vhost_scsi *vs;
> struct vhost_virtqueue **vqs;
> - int r, i;
> + int r = -ENOMEM, i;
>
> - vs = kzalloc(sizeof(*vs), GFP_KERNEL);
> - if (!vs)
> - return -ENOMEM;
> + vs = kzalloc(sizeof(*vs), GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
> + if (!vs) {
> + vs = vzalloc(sizeof(*vs));
> + if (!vs)
> + goto err_vs;
> + }
>
> vqs = kmalloc(VHOST_SCSI_MAX_VQ * sizeof(*vqs), GFP_KERNEL);
> - if (!vqs) {
> - kfree(vs);
> - return -ENOMEM;
> - }
> + if (!vqs)
> + goto err_vqs;
>
> vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
> vhost_work_init(&vs->vs_event_work, tcm_vhost_evt_work);
> @@ -1407,14 +1416,18 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
>
> tcm_vhost_init_inflight(vs, NULL);
>
> - if (r < 0) {
> - kfree(vqs);
> - kfree(vs);
> - return r;
> - }
> + if (r < 0)
> + goto err_init;
>
> f->private_data = vs;
> return 0;
> +
> +err_init:
> + kfree(vqs);
> +err_vqs:
> + vhost_scsi_free(vs);
> +err_vs:
> + return r;
> }
>
> static int vhost_scsi_release(struct inode *inode, struct file *f)
> @@ -1431,7 +1444,7 @@ static int vhost_scsi_release(struct inode *inode, struct file *f)
> /* Jobs can re-queue themselves in evt kick handler. Do extra flush. */
> vhost_scsi_flush(vs);
> kfree(vs->dev.vqs);
> - kfree(vs);
> + vhost_scsi_free(vs);
> return 0;
> }
>
> --
> MST
--
Asias
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