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author | Roman Gushchin <guro@fb.com> | 2019-05-29 18:03:58 -0700 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2019-05-31 16:52:56 -0700 |
commit | b936ca643ade11f265fa10e5fb71c20d9c5243f1 (patch) | |
tree | fab6cc685363f4f9901fecf6335a8d8e6974f8b3 /include/linux/bpf.h | |
parent | 3539b96e041c06e4317082816d90ec09160aeb11 (diff) | |
download | linux-b936ca643ade11f265fa10e5fb71c20d9c5243f1.tar.gz linux-b936ca643ade11f265fa10e5fb71c20d9c5243f1.tar.bz2 linux-b936ca643ade11f265fa10e5fb71c20d9c5243f1.zip |
bpf: rework memlock-based memory accounting for maps
In order to unify the existing memlock charging code with the
memcg-based memory accounting, which will be added later, let's
rework the current scheme.
Currently the following design is used:
1) .alloc() callback optionally checks if the allocation will likely
succeed using bpf_map_precharge_memlock()
2) .alloc() performs actual allocations
3) .alloc() callback calculates map cost and sets map.memory.pages
4) map_create() calls bpf_map_init_memlock() which sets map.memory.user
and performs actual charging; in case of failure the map is
destroyed
<map is in use>
1) bpf_map_free_deferred() calls bpf_map_release_memlock(), which
performs uncharge and releases the user
2) .map_free() callback releases the memory
The scheme can be simplified and made more robust:
1) .alloc() calculates map cost and calls bpf_map_charge_init()
2) bpf_map_charge_init() sets map.memory.user and performs actual
charge
3) .alloc() performs actual allocations
<map is in use>
1) .map_free() callback releases the memory
2) bpf_map_charge_finish() performs uncharge and releases the user
The new scheme also allows to reuse bpf_map_charge_init()/finish()
functions for memcg-based accounting. Because charges are performed
before actual allocations and uncharges after freeing the memory,
no bogus memory pressure can be created.
In cases when the map structure is not available (e.g. it's not
created yet, or is already destroyed), on-stack bpf_map_memory
structure is used. The charge can be transferred with the
bpf_map_charge_move() function.
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf.h')
-rw-r--r-- | include/linux/bpf.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2e7c1c40d949..3c8f24f402bf 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -650,9 +650,12 @@ struct bpf_map *__bpf_map_get(struct fd f); struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref); void bpf_map_put_with_uref(struct bpf_map *map); void bpf_map_put(struct bpf_map *map); -int bpf_map_precharge_memlock(u32 pages); int bpf_map_charge_memlock(struct bpf_map *map, u32 pages); void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages); +int bpf_map_charge_init(struct bpf_map_memory *mem, u32 pages); +void bpf_map_charge_finish(struct bpf_map_memory *mem); +void bpf_map_charge_move(struct bpf_map_memory *dst, + struct bpf_map_memory *src); void *bpf_map_area_alloc(size_t size, int numa_node); void bpf_map_area_free(void *base); void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr); |