[PATCH] vhost-net: fall back to vmalloc if high-order allocation fails
From: Romain Francoise <hidden>
Date: 2013-01-23 20:46:54
Also in:
kvm, lkml
Subsystem:
the rest, virtio host (vhost) · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
Creating a vhost-net device allocates an object large enough (34320 bytes on x86-64) to trigger an order-4 allocation, which may fail if memory if fragmented: libvirtd: page allocation failure: order:4, mode:0x2000d0 ... SLAB: Unable to allocate memory on node 0 (gfp=0xd0) cache: size-65536, object size: 65536, order: 4 node 0: slabs: 8/8, objs: 8/8, free: 0 In that situation, rather than forcing the caller to use regular virtio-net, try to allocate the descriptor with vmalloc(). Signed-off-by: Romain Francoise <redacted> --- drivers/vhost/net.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index ebd08b2..1ded79b 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c@@ -18,6 +18,7 @@ #include <linux/rcupdate.h> #include <linux/file.h> #include <linux/slab.h> +#include <linux/vmalloc.h> #include <linux/net.h> #include <linux/if_packet.h>
@@ -603,12 +604,23 @@ static void handle_rx_net(struct vhost_work *work) handle_rx(net); } +static void vhost_net_kvfree(void *addr) +{ + if (is_vmalloc_addr(addr)) + vfree(addr); + else + kfree(addr); +} + static int vhost_net_open(struct inode *inode, struct file *f) { - struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL); + struct vhost_net *n; struct vhost_dev *dev; int r; + n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN); + if (!n) + n = vmalloc(sizeof *n); if (!n) return -ENOMEM;
@@ -617,7 +629,7 @@ static int vhost_net_open(struct inode *inode, struct file *f) n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick; r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX); if (r < 0) { - kfree(n); + vhost_net_kvfree(n); return r; }
@@ -719,7 +731,7 @@ static int vhost_net_release(struct inode *inode, struct file *f) /* We do an extra flush before freeing memory, * since jobs can re-queue themselves. */ vhost_net_flush(n); - kfree(n); + vhost_net_kvfree(n); return 0; }
--
1.8.1.1