Virtualization - Jul 2016 - [PATCH] virtio: don't warn if we can't allocate indirect sglist

Don't print warning if memory allocation fails. The virtio driver can
handle allocation failure (it falls back to direct sglist), so there is
no functionality degradation.

This warning was observed when swapping to virtio scsi device because
there may be not enough free memory during swapping.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

---
 drivers/virtio/virtio_ring.c |    6 ++++++
 1 file changed, 6 insertions(+)

Index: linux-4.7-rc7/drivers/virtio/virtio_ring.c
==================================================================---
linux-4.7-rc7.orig/drivers/virtio/virtio_ring.c	2016-05-09 17:45:04.000000000
+0200
+++ linux-4.7-rc7/drivers/virtio/virtio_ring.c	2016-07-11 17:30:20.000000000
+0200
@@ -237,6 +237,12 @@ static struct vring_desc *alloc_indirect
 	 */
 	gfp &= ~__GFP_HIGHMEM;
 
+	/*
+	 * Don't warn if the allocation fails, because the driver
+	 * handles allocation failures gracefully.
+	 */
+	gfp |= __GFP_NOWARN;
+
 	desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp);
 	if (!desc)
 		return NULL;

On 07/11/2016 07:22 PM, Mikulas Patocka wrote:
> Don't print warning if memory allocation fails. The virtio driver can
> handle allocation failure (it falls back to direct sglist), so there is
> no functionality degradation.
> 
> This warning was observed when swapping to virtio scsi device because
> there may be not enough free memory during swapping.
> 
> Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger at
de.ibm.com>
> 
> ---
>  drivers/virtio/virtio_ring.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> Index: linux-4.7-rc7/drivers/virtio/virtio_ring.c
> ==================================================================> ---
linux-4.7-rc7.orig/drivers/virtio/virtio_ring.c	2016-05-09 17:45:04.000000000
+0200
> +++ linux-4.7-rc7/drivers/virtio/virtio_ring.c	2016-07-11
17:30:20.000000000 +0200
> @@ -237,6 +237,12 @@ static struct vring_desc *alloc_indirect
>  	 */
>  	gfp &= ~__GFP_HIGHMEM;
> 
> +	/*
> +	 * Don't warn if the allocation fails, because the driver
> +	 * handles allocation failures gracefully.
> +	 */
> +	gfp |= __GFP_NOWARN;
> +
>  	desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp);
>  	if (!desc)
>  		return NULL;
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