While checking opencoded users I've encountered that vhost code would really like to use kvmalloc with __GFP_REPEAT [1] so the following patch adds support for __GFP_REPEAT and converts both vhost users. So currently I am sitting on 3 patches. I will wait for more feedback - especially about potential split ups or cleanups few more days and then repost the whole series. [1] http://lkml.kernel.org/r/20170104150800.GO25453@xxxxxxxxxxxxxx --- >From 0b92e4d2e040524b878d4e7b9ee88fbad5284b33 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@xxxxxxxx> Date: Wed, 4 Jan 2017 18:01:39 +0100 Subject: [PATCH] mm: support __GFP_REPEAT in kvmalloc_node vhost code uses __GFP_REPEAT when allocating vhost_virtqueue resp. vhost_vsock because it would really like to prefer kmalloc to the vmalloc fallback - see 23cc5a991c7a ("vhost-net: extend device allocation to vmalloc") for more context. Michael Tsirkin has also noted: " __GFP_REPEAT overhead is during allocation time. Using vmalloc means all accesses are slowed down. Allocation is not on data path, accesses are. " Let's teach kvmalloc_node to handle __GFP_REPEAT properly. There are two things to be careful about. First we should prevent from the OOM killer and so have to involve __GFP_NORETRY by default and secondly override __GFP_REPEAT for !costly order requests as the __GFP_REPEAT is ignored for !costly orders. This patch shouldn't introduce any functional change. Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> --- drivers/vhost/net.c | 9 +++------ drivers/vhost/vsock.c | 9 +++------ mm/util.c | 9 +++++++-- 3 files changed, 13 insertions(+), 14 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 5dc34653274a..105cd04c7414 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -797,12 +797,9 @@ static int vhost_net_open(struct inode *inode, struct file *f) struct vhost_virtqueue **vqs; int i; - n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); - if (!n) { - n = vmalloc(sizeof *n); - if (!n) - return -ENOMEM; - } + n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_REPEAT); + if (!n) + return -ENOMEM; vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL); if (!vqs) { kvfree(n); diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index bbbf588540ed..7e0159867553 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -455,12 +455,9 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file) /* This struct is large and allocation could fail, fall back to vmalloc * if there is no other way. */ - vsock = kzalloc(sizeof(*vsock), GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); - if (!vsock) { - vsock = vmalloc(sizeof(*vsock)); - if (!vsock) - return -ENOMEM; - } + vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_REPEAT); + if (!vsock) + return -ENOMEM; vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL); if (!vqs) { diff --git a/mm/util.c b/mm/util.c index 8e4ea6cbe379..a2bfb85e60e5 100644 --- a/mm/util.c +++ b/mm/util.c @@ -348,8 +348,13 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) * Make sure that larger requests are not too disruptive - no OOM * killer and no allocation failure warnings as we have a fallback */ - if (size > PAGE_SIZE) - kmalloc_flags |= __GFP_NORETRY | __GFP_NOWARN; + if (size > PAGE_SIZE) { + kmalloc_flags |= __GFP_NOWARN; + + if (!(kmalloc_flags & __GFP_REPEAT) || + (size <= PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) + kmalloc_flags |= __GFP_NORETRY; + } ret = kmalloc_node(size, kmalloc_flags, node); -- 2.11.0 -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
