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virtio: net refill on out-of-memory

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If we run out of memory, use keventd to fill the buffer.  There's a
report of this happening: "Page allocation failures in guest",
Message-ID: <20090713115158.0a4892b0@mjolnir.ossman.eu>

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rusty Russell 2009-08-26 12:22:32 -07:00 committed by David S. Miller
parent 0b4f2928f1
commit 3161e453e4
1 changed files with 46 additions and 15 deletions
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61
drivers/net/virtio_net.c
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@ -70,6 +70,9 @@ struct virtnet_info
struct sk_buff_head recv;
struct sk_buff_head send;
/* Work struct for refilling if we run low on memory. */
struct delayed_work refill;
/* Chain pages by the private ptr. */
struct page *pages;
};
@ -273,19 +276,22 @@ drop:
dev_kfree_skb(skb);
}
static void try_fill_recv_maxbufs(struct virtnet_info *vi)
static bool try_fill_recv_maxbufs(struct virtnet_info *vi, gfp_t gfp)
{
struct sk_buff *skb;
struct scatterlist sg[2+MAX_SKB_FRAGS];
int num, err, i;
bool oom = false;
sg_init_table(sg, 2+MAX_SKB_FRAGS);
for (;;) {
struct virtio_net_hdr *hdr;
skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN + NET_IP_ALIGN);
if (unlikely(!skb))
if (unlikely(!skb)) {
oom = true;
break;
}
skb_reserve(skb, NET_IP_ALIGN);
skb_put(skb, MAX_PACKET_LEN);
@ -296,7 +302,7 @@ static void try_fill_recv_maxbufs(struct virtnet_info *vi)
if (vi->big_packets) {
for (i = 0; i < MAX_SKB_FRAGS; i++) {
skb_frag_t *f = &skb_shinfo(skb)->frags[i];
f->page = get_a_page(vi, GFP_ATOMIC);
f->page = get_a_page(vi, gfp);
if (!f->page)
break;
@ -325,31 +331,35 @@ static void try_fill_recv_maxbufs(struct virtnet_info *vi)
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);
return !oom;
}
static void try_fill_recv(struct virtnet_info *vi)
/* Returns false if we couldn't fill entirely (OOM). */
static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp)
{
struct sk_buff *skb;
struct scatterlist sg[1];
int err;
bool oom = false;
if (!vi->mergeable_rx_bufs) {
try_fill_recv_maxbufs(vi);
return;
}
if (!vi->mergeable_rx_bufs)
return try_fill_recv_maxbufs(vi, gfp);
for (;;) {
skb_frag_t *f;
skb = netdev_alloc_skb(vi->dev, GOOD_COPY_LEN + NET_IP_ALIGN);
if (unlikely(!skb))
if (unlikely(!skb)) {
oom = true;
break;
}
skb_reserve(skb, NET_IP_ALIGN);
f = &skb_shinfo(skb)->frags[0];
f->page = get_a_page(vi, GFP_ATOMIC);
f->page = get_a_page(vi, gfp);
if (!f->page) {
oom = true;
kfree_skb(skb);
break;
}
@ -373,6 +383,7 @@ static void try_fill_recv(struct virtnet_info *vi)
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);
return !oom;
}
static void skb_recv_done(struct virtqueue *rvq)
@ -385,6 +396,23 @@ static void skb_recv_done(struct virtqueue *rvq)
}
}
static void refill_work(struct work_struct *work)
{
struct virtnet_info *vi;
bool still_empty;
vi = container_of(work, struct virtnet_info, refill.work);
napi_disable(&vi->napi);
try_fill_recv(vi, GFP_KERNEL);
still_empty = (vi->num == 0);
napi_enable(&vi->napi);
/* In theory, this can happen: if we don't get any buffers in
* we will *never* try to fill again. */
if (still_empty)
schedule_delayed_work(&vi->refill, HZ/2);
}
static int virtnet_poll(struct napi_struct *napi, int budget)
{
struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
@ -400,10 +428,10 @@ again:
received++;
}
/* FIXME: If we oom and completely run out of inbufs, we need
* to start a timer trying to fill more. */
if (vi->num < vi->max / 2)
try_fill_recv(vi);
if (vi->num < vi->max / 2) {
if (!try_fill_recv(vi, GFP_ATOMIC))
schedule_delayed_work(&vi->refill, 0);
}
/* Out of packets? */
if (received < budget) {
@ -893,6 +921,7 @@ static int virtnet_probe(struct virtio_device *vdev)
vi->vdev = vdev;
vdev->priv = vi;
vi->pages = NULL;
INIT_DELAYED_WORK(&vi->refill, refill_work);
/* If they give us a callback when all buffers are done, we don't need
* the timer. */
@ -941,7 +970,7 @@ static int virtnet_probe(struct virtio_device *vdev)
}
/* Last of all, set up some receive buffers. */
try_fill_recv(vi);
try_fill_recv(vi, GFP_KERNEL);
/* If we didn't even get one input buffer, we're useless. */
if (vi->num == 0) {
@ -958,6 +987,7 @@ static int virtnet_probe(struct virtio_device *vdev)
unregister:
unregister_netdev(dev);
cancel_delayed_work_sync(&vi->refill);
free_vqs:
vdev->config->del_vqs(vdev);
free:
@ -986,6 +1016,7 @@ static void virtnet_remove(struct virtio_device *vdev)
BUG_ON(vi->num != 0);
unregister_netdev(vi->dev);
cancel_delayed_work_sync(&vi->refill);
vdev->config->del_vqs(vi->vdev);