From 23cc5a991c7a9fb7e6d6550e65cee4f4173111c5 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 23 Jan 2013 21:46:47 +0100 Subject: [PATCH] vhost-net: extend device allocation to vmalloc Michael Mueller provided a patch to reduce the size of vhost-net structure as some allocations could fail under memory pressure/fragmentation. We are still left with high order allocations though. This patch is handling the problem at the core level, allowing vhost structures to use vmalloc() if kmalloc() failed. As vmalloc() adds overhead on a critical network path, add __GFP_REPEAT to kzalloc() flags to do this fallback only when really needed. People are still looking at cleaner ways to handle the problem at the API level, probably passing in multiple iovecs. This hack seems consistent with approaches taken since then by drivers/vhost/scsi.c and net/core/dev.c Based on patch by Romain Francoise. Cc: Michael Mueller Signed-off-by: Romain Francoise Acked-by: Michael S. Tsirkin --- drivers/vhost/net.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index be414d2b2b22..e489161d0feb 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -699,18 +700,30 @@ static void handle_rx_net(struct vhost_work *work) handle_rx(net); } +static void vhost_net_free(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; struct vhost_virtqueue **vqs; int i; - if (!n) - return -ENOMEM; + n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); + if (!n) { + n = vmalloc(sizeof *n); + if (!n) + return -ENOMEM; + } vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL); if (!vqs) { - kfree(n); + vhost_net_free(n); return -ENOMEM; } @@ -827,7 +840,7 @@ static int vhost_net_release(struct inode *inode, struct file *f) * since jobs can re-queue themselves. */ vhost_net_flush(n); kfree(n->dev.vqs); - kfree(n); + vhost_net_free(n); return 0; } -- 2.20.1