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bpf: Use pcpu_alloc_size() in bpf_mem_free{_rcu}()

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For bpf_global_percpu_ma, the pointer passed to bpf_mem_free_rcu() is
allocated by kmalloc() and its size is fixed (16-bytes on x86-64). So
no matter which cache allocates the dynamic per-cpu area, on x86-64
cache[2] will always be used to free the per-cpu area.

Fix the unbalance by checking whether the bpf memory allocator is
per-cpu or not and use pcpu_alloc_size() instead of ksize() to
find the correct cache for per-cpu free.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2023-10-20 21:31:59 +08:00 committed by Alexei Starovoitov
parent baa8fdecd8
commit 3f2189e4f7
2 changed files with 15 additions and 2 deletions
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1
include/linux/bpf_mem_alloc.h
View File

@ -11,6 +11,7 @@ struct bpf_mem_caches;
struct bpf_mem_alloc {
struct bpf_mem_caches __percpu *caches;
struct bpf_mem_cache __percpu *cache;
bool percpu;
struct work_struct work;
};

16
kernel/bpf/memalloc.c
View File

@ -525,6 +525,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
/* room for llist_node and per-cpu pointer */
if (percpu)
percpu_size = LLIST_NODE_SZ + sizeof(void *);
ma->percpu = percpu;
if (size) {
pc = __alloc_percpu_gfp(sizeof(*pc), 8, GFP_KERNEL);
@ -874,6 +875,17 @@ void notrace *bpf_mem_alloc(struct bpf_mem_alloc *ma, size_t size)
return !ret ? NULL : ret + LLIST_NODE_SZ;
}
static notrace int bpf_mem_free_idx(void *ptr, bool percpu)
{
size_t size;
if (percpu)
size = pcpu_alloc_size(*((void **)ptr));
else
size = ksize(ptr - LLIST_NODE_SZ);
return bpf_mem_cache_idx(size);
}
void notrace bpf_mem_free(struct bpf_mem_alloc *ma, void *ptr)
{
int idx;
@ -881,7 +893,7 @@ void notrace bpf_mem_free(struct bpf_mem_alloc *ma, void *ptr)
if (!ptr)
return;
idx = bpf_mem_cache_idx(ksize(ptr - LLIST_NODE_SZ));
idx = bpf_mem_free_idx(ptr, ma->percpu);
if (idx < 0)
return;
@ -895,7 +907,7 @@ void notrace bpf_mem_free_rcu(struct bpf_mem_alloc *ma, void *ptr)
if (!ptr)
return;
idx = bpf_mem_cache_idx(ksize(ptr - LLIST_NODE_SZ));
idx = bpf_mem_free_idx(ptr, ma->percpu);
if (idx < 0)
return;