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| author | Alexei Starovoitov <ast@kernel.org> | 2025-10-15 03:07:00 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2025-10-15 13:22:22 +0300 |
| commit | 5fb750e8a9ae123b2034771b864b8a21dbef65cd (patch) | |
| tree | 468ef6b398c37c1f195b3f09e687cd522be29bf8 /include/linux | |
| parent | e603a342cf7ecd64ef8f36207dfe1caacb9e2583 (diff) | |
| download | linux-5fb750e8a9ae123b2034771b864b8a21dbef65cd.tar.xz | |
bpf: Replace bpf_map_kmalloc_node() with kmalloc_nolock() to allocate bpf_async_cb structures.
The following kmemleak splat:
[ 8.105530] kmemleak: Trying to color unknown object at 0xff11000100e918c0 as Black
[ 8.106521] Call Trace:
[ 8.106521] <TASK>
[ 8.106521] dump_stack_lvl+0x4b/0x70
[ 8.106521] kvfree_call_rcu+0xcb/0x3b0
[ 8.106521] ? hrtimer_cancel+0x21/0x40
[ 8.106521] bpf_obj_free_fields+0x193/0x200
[ 8.106521] htab_map_update_elem+0x29c/0x410
[ 8.106521] bpf_prog_cfc8cd0f42c04044_overwrite_cb+0x47/0x4b
[ 8.106521] bpf_prog_8c30cd7c4db2e963_overwrite_timer+0x65/0x86
[ 8.106521] bpf_prog_test_run_syscall+0xe1/0x2a0
happens due to the combination of features and fixes, but mainly due to
commit 6d78b4473cdb ("bpf: Tell memcg to use allow_spinning=false path in bpf_timer_init()")
It's using __GFP_HIGH, which instructs slub/kmemleak internals to skip
kmemleak_alloc_recursive() on allocation, so subsequent kfree_rcu()->
kvfree_call_rcu()->kmemleak_ignore() complains with the above splat.
To fix this imbalance, replace bpf_map_kmalloc_node() with
kmalloc_nolock() and kfree_rcu() with call_rcu() + kfree_nolock() to
make sure that the objects allocated with kmalloc_nolock() are freed
with kfree_nolock() rather than the implicit kfree() that kfree_rcu()
uses internally.
Note, the kmalloc_nolock() happens under bpf_spin_lock_irqsave(), so
it will always fail in PREEMPT_RT. This is not an issue at the moment,
since bpf_timers are disabled in PREEMPT_RT. In the future
bpf_spin_lock will be replaced with state machine similar to
bpf_task_work.
Fixes: 6d78b4473cdb ("bpf: Tell memcg to use allow_spinning=false path in bpf_timer_init()")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/bpf/20251015000700.28988-1-alexei.starovoitov@gmail.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/bpf.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a98c83346134..d808253f2e94 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2499,6 +2499,8 @@ int bpf_map_alloc_pages(const struct bpf_map *map, int nid, #ifdef CONFIG_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, + int node); void *bpf_map_kzalloc(const struct bpf_map *map, size_t size, gfp_t flags); void *bpf_map_kvcalloc(struct bpf_map *map, size_t n, size_t size, gfp_t flags); @@ -2511,6 +2513,8 @@ void __percpu *bpf_map_alloc_percpu(const struct bpf_map *map, size_t size, */ #define bpf_map_kmalloc_node(_map, _size, _flags, _node) \ kmalloc_node(_size, _flags, _node) +#define bpf_map_kmalloc_nolock(_map, _size, _flags, _node) \ + kmalloc_nolock(_size, _flags, _node) #define bpf_map_kzalloc(_map, _size, _flags) \ kzalloc(_size, _flags) #define bpf_map_kvcalloc(_map, _n, _size, _flags) \ |