From: Hou Tao Date: Wed, 8 Jan 2025 01:07:21 +0000 (+0800) Subject: bpf: Disable migration in bpf_selem_free_rcu X-Git-Tag: v6.14-rc1~133^2~18^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=090d7f2e640b265335ac0a5a8e09a99f7f28f567;p=thirdparty%2Flinux.git bpf: Disable migration in bpf_selem_free_rcu bpf_selem_free_rcu() calls bpf_obj_free_fields() to free the special fields in map value (e.g., kptr). Since kptrs may be allocated from bpf memory allocator, migrate_{disable|enable} pairs are necessary for the freeing of these kptrs. To simplify reasoning about when migrate_disable() is needed for the freeing of these dynamically-allocated kptrs, let the caller to guarantee migration is disabled before invoking bpf_obj_free_fields(). Therefore, the patch adds migrate_{disable|enable} pair in bpf_selem_free_rcu(). The migrate_{disable|enable} pairs in the underlying implementation of bpf_obj_free_fields() will be removed by the following patch. Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20250108010728.207536-10-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index e94820f6b0cd3..615a3034baeb5 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -217,7 +217,10 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu) selem = container_of(rcu, struct bpf_local_storage_elem, rcu); /* The bpf_local_storage_map_free will wait for rcu_barrier */ smap = rcu_dereference_check(SDATA(selem)->smap, 1); + + migrate_disable(); bpf_obj_free_fields(smap->map.record, SDATA(selem)->data); + migrate_enable(); bpf_mem_cache_raw_free(selem); }