Messages in this thread Patch in this message | | | From | tglozar@redhat ... | Subject | [PATCH RFC net] bpf: sockmap: Remove preempt_disable in sock_map_sk_acquire | Date | Wed, 26 Jul 2023 10:50:03 +0200 |
| |
From: Tomas Glozar <tglozar@redhat.com>
Disabling preemption in sock_map_sk_acquire conflicts with GFP_ATOMIC allocation later in sk_psock_init_link on PREEMPT_RT kernels, since GFP_ATOMIC might sleep on RT (see bpf: Make BPF and PREEMPT_RT co-exist patchset notes for details).
This causes calling bpf_map_update_elem on BPF_MAP_TYPE_SOCKMAP maps to BUG (sleeping function called from invalid context) on RT kernels.
preempt_disable was introduced together with lock_sk and rcu_read_lock in commit 99ba2b5aba24e ("bpf: sockhash, disallow bpf_tcp_close and update in parallel") with no comment on why it is necessary.
Remove preempt_disable to fix BUG in sock_map_update_common on RT.
Signed-off-by: Tomas Glozar <tglozar@redhat.com> --- net/core/sock_map.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 19538d628714..08ab108206bf 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -115,7 +115,6 @@ static void sock_map_sk_acquire(struct sock *sk) __acquires(&sk->sk_lock.slock) { lock_sock(sk); - preempt_disable(); rcu_read_lock(); } @@ -123,7 +122,6 @@ static void sock_map_sk_release(struct sock *sk) __releases(&sk->sk_lock.slock) { rcu_read_unlock(); - preempt_enable(); release_sock(sk); } base-commit: 22117b3ae6e37d07225653d9ae5ae86b3a54f99c -- 2.39.3
| |