On Wed, Jul 12, 2023 at 4:44 PM Daniel Xu <dxu@xxxxxxxxx> wrote:
> +#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
> + case NFPROTO_IPV6:
> + rcu_read_lock();
> + v6_hook = rcu_dereference(nf_defrag_v6_hook);
> + if (!v6_hook) {
> + rcu_read_unlock();
> + err = request_module("nf_defrag_ipv6");
> + if (err)
> + return err < 0 ? err : -EINVAL;
> +
> + rcu_read_lock();
> + v6_hook = rcu_dereference(nf_defrag_v6_hook);
> + if (!v6_hook) {
> + WARN_ONCE(1, "nf_defrag_ipv6_hooks bad registration");
> + err = -ENOENT;
> + goto out_v6;
> + }
> + }
> +
> + err = v6_hook->enable(link->net);
I was about to apply, but luckily caught this issue in my local test:
[ 18.462448] BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:283
[ 18.463238] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid:
2042, name: test_progs
[ 18.463927] preempt_count: 0, expected: 0
[ 18.464249] RCU nest depth: 1, expected: 0
[ 18.464631] CPU: 15 PID: 2042 Comm: test_progs Tainted: G
O 6.4.0-04319-g6f6ec4fa00dc #4896
[ 18.465480] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
[ 18.466531] Call Trace:
[ 18.466767] <TASK>
[ 18.466975] dump_stack_lvl+0x32/0x40
[ 18.467325] __might_resched+0x129/0x180
[ 18.467691] mutex_lock+0x1a/0x40
[ 18.468057] nf_defrag_ipv4_enable+0x16/0x70
[ 18.468467] bpf_nf_link_attach+0x141/0x300
[ 18.468856] __sys_bpf+0x133e/0x26d0
You cannot call mutex under rcu_read_lock.
Please make sure you have all kernel debug flags on in your testing.
