diff options
| author | Hou Tao <houtao1@huawei.com> | 2023-10-20 16:32:01 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-10-21 00:15:13 +0300 |
| commit | e383a45902337356d9ccad797094a27c6b2150f9 (patch) | |
| tree | 4d1e5d7c3b683f1bc68676182c98843fdac5db59 /include/linux/bpf.h | |
| parent | e581a3461de3f129cfe888a67d9f31086328271f (diff) | |
| download | linux-e383a45902337356d9ccad797094a27c6b2150f9.tar.xz | |
bpf: Use bpf_global_percpu_ma for per-cpu kptr in __bpf_obj_drop_impl()
The following warning was reported when running "./test_progs -t
test_bpf_ma/percpu_free_through_map_free":
------------[ cut here ]------------
WARNING: CPU: 1 PID: 68 at kernel/bpf/memalloc.c:342
CPU: 1 PID: 68 Comm: kworker/u16:2 Not tainted 6.6.0-rc2+ #222
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Workqueue: events_unbound bpf_map_free_deferred
RIP: 0010:bpf_mem_refill+0x21c/0x2a0
......
Call Trace:
<IRQ>
? bpf_mem_refill+0x21c/0x2a0
irq_work_single+0x27/0x70
irq_work_run_list+0x2a/0x40
irq_work_run+0x18/0x40
__sysvec_irq_work+0x1c/0xc0
sysvec_irq_work+0x73/0x90
</IRQ>
<TASK>
asm_sysvec_irq_work+0x1b/0x20
RIP: 0010:unit_free+0x50/0x80
......
bpf_mem_free+0x46/0x60
__bpf_obj_drop_impl+0x40/0x90
bpf_obj_free_fields+0x17d/0x1a0
array_map_free+0x6b/0x170
bpf_map_free_deferred+0x54/0xa0
process_scheduled_works+0xba/0x370
worker_thread+0x16d/0x2e0
kthread+0x105/0x140
ret_from_fork+0x39/0x60
ret_from_fork_asm+0x1b/0x30
</TASK>
---[ end trace 0000000000000000 ]---
The reason is simple: __bpf_obj_drop_impl() does not know the freeing
field is a per-cpu pointer and it uses bpf_global_ma to free the
pointer. Because bpf_global_ma is not a per-cpu allocator, so ksize() is
used to select the corresponding cache. The bpf_mem_cache with 16-bytes
unit_size will always be selected to do the unmatched free and it will
trigger the warning in free_bulk() eventually.
Because per-cpu kptr doesn't support list or rb-tree now, so fix the
problem by only checking whether or not the type of kptr is per-cpu in
bpf_obj_free_fields(), and using bpf_global_percpu_ma to these kptrs.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-7-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ebd412179771..b4825d3cdb29 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2058,7 +2058,7 @@ struct btf_record *btf_record_dup(const struct btf_record *rec); bool btf_record_equal(const struct btf_record *rec_a, const struct btf_record *rec_b); void bpf_obj_free_timer(const struct btf_record *rec, void *obj); void bpf_obj_free_fields(const struct btf_record *rec, void *obj); -void __bpf_obj_drop_impl(void *p, const struct btf_record *rec); +void __bpf_obj_drop_impl(void *p, const struct btf_record *rec, bool percpu); struct bpf_map *bpf_map_get(u32 ufd); struct bpf_map *bpf_map_get_with_uref(u32 ufd); |