Commit 817593af authored by Puranjay Mohan's avatar Puranjay Mohan Committed by Alexei Starovoitov
Browse files

bpf: syscall: Introduce memcg enter/exit helpers 



Introduce bpf_map_memcg_enter() and bpf_map_memcg_exit() helpers to
reduce code duplication in memcg context management.

bpf_map_memcg_enter() gets the memcg from the map, sets it as active,
and returns both the previous and the now active memcg.

bpf_map_memcg_exit() restores the previous active memcg and releases the
reference obtained during enter.

Signed-off-by: default avatarPuranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260102200230.25168-2-puranjay@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent e40030a4

include/linux/bpf.h

+15 −0
Original line number Diff line number Diff line
@@ -2608,6 +2608,10 @@ struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id); 
int bpf_map_alloc_pages(const struct bpf_map *map, int nid,

			unsigned long nr_pages, struct page **page_array);

#ifdef CONFIG_MEMCG

void bpf_map_memcg_enter(const struct bpf_map *map, struct mem_cgroup **old_memcg,

			 struct mem_cgroup **new_memcg);

void bpf_map_memcg_exit(struct mem_cgroup *old_memcg,

			struct mem_cgroup *memcg);

void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags,

			   int node);

void *bpf_map_kmalloc_nolock(const struct bpf_map *map, size_t size, gfp_t flags,
@@ -2632,6 +2636,17 @@ void __percpu *bpf_map_alloc_percpu(const struct bpf_map *map, size_t size, 
		kvcalloc(_n, _size, _flags)

#define bpf_map_alloc_percpu(_map, _size, _align, _flags)	\

		__alloc_percpu_gfp(_size, _align, _flags)

static inline void bpf_map_memcg_enter(const struct bpf_map *map, struct mem_cgroup **old_memcg,

				       struct mem_cgroup **new_memcg)

{

	*new_memcg = NULL;

	*old_memcg = NULL;

}



static inline void bpf_map_memcg_exit(struct mem_cgroup *old_memcg,

				      struct mem_cgroup *memcg)

{

}

#endif



static inline int

kernel/bpf/syscall.c

+26 −28
Original line number Diff line number Diff line
@@ -505,17 +505,29 @@ static struct mem_cgroup *bpf_map_get_memcg(const struct bpf_map *map) 
	return root_mem_cgroup;

}



void bpf_map_memcg_enter(const struct bpf_map *map, struct mem_cgroup **old_memcg,

			 struct mem_cgroup **new_memcg)

{

	*new_memcg = bpf_map_get_memcg(map);

	*old_memcg = set_active_memcg(*new_memcg);

}



void bpf_map_memcg_exit(struct mem_cgroup *old_memcg,

			struct mem_cgroup *new_memcg)

{

	set_active_memcg(old_memcg);

	mem_cgroup_put(new_memcg);

}



void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags,

			   int node)

{

	struct mem_cgroup *memcg, *old_memcg;

	void *ptr;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	ptr = kmalloc_node(size, flags | __GFP_ACCOUNT, node);

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

	bpf_map_memcg_exit(old_memcg, memcg);



	return ptr;

}
@@ -526,11 +538,9 @@ void *bpf_map_kmalloc_nolock(const struct bpf_map *map, size_t size, gfp_t flags 
	struct mem_cgroup *memcg, *old_memcg;

	void *ptr;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	ptr = kmalloc_nolock(size, flags | __GFP_ACCOUNT, node);

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

	bpf_map_memcg_exit(old_memcg, memcg);



	return ptr;

}
@@ -540,11 +550,9 @@ void *bpf_map_kzalloc(const struct bpf_map *map, size_t size, gfp_t flags) 
	struct mem_cgroup *memcg, *old_memcg;

	void *ptr;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	ptr = kzalloc(size, flags | __GFP_ACCOUNT);

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

	bpf_map_memcg_exit(old_memcg, memcg);



	return ptr;

}
@@ -555,11 +563,9 @@ void *bpf_map_kvcalloc(struct bpf_map *map, size_t n, size_t size, 
	struct mem_cgroup *memcg, *old_memcg;

	void *ptr;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	ptr = kvcalloc(n, size, flags | __GFP_ACCOUNT);

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

	bpf_map_memcg_exit(old_memcg, memcg);



	return ptr;

}
@@ -570,11 +576,9 @@ void __percpu *bpf_map_alloc_percpu(const struct bpf_map *map, size_t size, 
	struct mem_cgroup *memcg, *old_memcg;

	void __percpu *ptr;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	ptr = __alloc_percpu_gfp(size, align, flags | __GFP_ACCOUNT);

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

	bpf_map_memcg_exit(old_memcg, memcg);



	return ptr;

}
@@ -612,12 +616,9 @@ int bpf_map_alloc_pages(const struct bpf_map *map, int nid, 
	unsigned long i, j;

	struct page *pg;

	int ret = 0;

#ifdef CONFIG_MEMCG

	struct mem_cgroup *memcg, *old_memcg;



	memcg = bpf_map_get_memcg(map);

	old_memcg = set_active_memcg(memcg);

#endif

	bpf_map_memcg_enter(map, &old_memcg, &memcg);

	for (i = 0; i < nr_pages; i++) {

		pg = __bpf_alloc_page(nid);
@@ -631,10 +632,7 @@ int bpf_map_alloc_pages(const struct bpf_map *map, int nid, 
		break;

	}



#ifdef CONFIG_MEMCG

	set_active_memcg(old_memcg);

	mem_cgroup_put(memcg);

#endif

	bpf_map_memcg_exit(old_memcg, memcg);

	return ret;

}