On Wed, May 22, 2024 at 06:59 AM +08, Hillf Danton wrote: > On Tue, 21 May 2024 08:38:52 -0700 Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> >> On Sun, May 12, 2024 at 12:22=E2=80=AFAM Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote: >> > --- a/net/core/sock_map.c >> > +++ b/net/core/sock_map.c >> > @@ -142,6 +142,7 @@ static void sock_map_del_link(struct sock *sk, >> > bool strp_stop =3D false, verdict_stop =3D false; >> > struct sk_psock_link *link, *tmp; >> > >> > + rcu_read_lock(); >> > spin_lock_bh(&psock->link_lock); >> >> I think this is incorrect. >> spin_lock_bh may sleep in RT and it won't be safe to do in rcu cs. > > Could you specify why it won't be safe in rcu cs if you are right? > What does rcu look like in RT if not nothing? RCU readers can't block, while spinlock RT doesn't disable preemption. https://docs.kernel.org/RCU/rcu.html https://docs.kernel.org/locking/locktypes.html#spinlock-t-and-preempt-rt I've finally gotten around to testing proposed fix that just disallows map_delete_elem on sockmap/sockhash from BPF tracing progs completely. This should put an end to this saga of syzkaller reports. https://lore.kernel.org/all/87jzjnxaqf.fsf@xxxxxxxxxxxxxx/
