From: Tomas Glozar tglozar@redhat.com
[ Upstream commit 13d2618b48f15966d1adfe1ff6a1985f5eef40ba ]
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"), probably to match disabled migration of BPF programs, and is no longer necessary.
Remove preempt_disable to fix BUG in sock_map_update_common on RT.
Signed-off-by: Tomas Glozar tglozar@redhat.com Reviewed-by: Jakub Sitnicki jakub@cloudflare.com Link: https://lore.kernel.org/all/20200224140131.461979697@linutronix.de/ Fixes: 99ba2b5aba24 ("bpf: sockhash, disallow bpf_tcp_close and update in parallel") Reviewed-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/r/20230728064411.305576-1-tglozar@redhat.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d382672018928..c84e5073c0b66 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -117,7 +117,6 @@ static void sock_map_sk_acquire(struct sock *sk) __acquires(&sk->sk_lock.slock) { lock_sock(sk); - preempt_disable(); rcu_read_lock(); }
@@ -125,7 +124,6 @@ static void sock_map_sk_release(struct sock *sk) __releases(&sk->sk_lock.slock) { rcu_read_unlock(); - preempt_enable(); release_sock(sk); }