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xsk: account ring allocations to memcg

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AF_XDP rings are allocated from setsockopt() and can be mapped into user
space.  The shared xskq_create() helper allocates the ring backing memory,
but the user-controlled and long-lived allocation is not charged as kmem
to the allocating memory cgroup.

The current implementation uses vmalloc_user(), which allocates the
backing pages with GFP_KERNEL | __GFP_ZERO.  Use the same VM_USERMAP
vmalloc path, but pass GFP_KERNEL_ACCOUNT so the ring backing pages are
attributed to memcg/kmem and can be constrained by existing cgroup memory
limits.  This keeps the existing zeroing and mmap semantics while avoiding
AF_XDP-specific optmem or RLIMIT_MEMLOCK accounting.

Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20260731164623.4694-2-zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Zihan Xi 2026-07-31 16:46:23 +00:00 committed by Jakub Kicinski
parent d21a374995
commit b0057c68df
1 changed files with 11 additions and 1 deletions
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12
net/xdp/xsk_queue.c
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@ -9,6 +9,8 @@
#include <linux/vmalloc.h>
#include <net/xdp_sock_drv.h>
#include <asm/shmparam.h>
#include "xsk_queue.h"
static size_t xskq_get_ring_size(struct xsk_queue *q, bool umem_queue)
@ -21,6 +23,14 @@ static size_t xskq_get_ring_size(struct xsk_queue *q, bool umem_queue)
return struct_size(rxtx_ring, desc, q->nentries);
}
static void *xskq_vmalloc_user(unsigned long size)
{
return __vmalloc_node_range(size, SHMLBA, VMALLOC_START, VMALLOC_END,
GFP_KERNEL_ACCOUNT | __GFP_ZERO, PAGE_KERNEL,
VM_USERMAP, NUMA_NO_NODE,
__builtin_return_address(0));
}
struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
{
struct xsk_queue *q;
@ -46,7 +56,7 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
size = PAGE_ALIGN(size);
q->ring = vmalloc_user(size);
q->ring = xskq_vmalloc_user(size);
if (!q->ring) {
kfree(q);
return NULL;