Re: net: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected in skb_array_produce

[Jason Wang]

On 2017年02月10日 02:10, Michael S. Tsirkin wrote:

On Thu, Feb 09, 2017 at 05:02:31AM -0500, Jason Wang wrote:

----- Original Message -----

Hello,

I've got the following report while running syzkaller fuzzer on mmotm
(git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git)
remotes/mmotm/auto-latest ee4ba7533626ba7bf2f8b992266467ac9fdc045e:

[...]

other info that might help us debug this:

  Possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&(&r->consumer_lock)->rlock);
                                local_irq_disable();
                                lock(&(&r->producer_lock)->rlock);
                                lock(&(&r->consumer_lock)->rlock);
   <Interrupt>
     lock(&(&r->producer_lock)->rlock);

Thanks a lot for the testing.

Looks like we could address this by using skb_array_consume_bh() instead.

Could you pls verify if the following patch works?

I think we should use _bh for the produce call as well,
since resizing takes the producer lock.

Looks not since irq was disabled during resizing?

Thanks