On Thu, Sep 08, 2022 at 01:35:02AM +0900, Shigeru Yoshida wrote:
> syzbot reported hung task [1]. The following program is a simplified
> version of the reproducer:
>
> int main(void)
> {
> int sv[2], fd;
>
> if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0)
> return 1;
> if ((fd = open("/dev/nbd0", 0)) < 0)
> return 1;
> if (ioctl(fd, NBD_SET_SIZE_BLOCKS, 0x81) < 0)
> return 1;
> if (ioctl(fd, NBD_SET_SOCK, sv[0]) < 0)
> return 1;
> if (ioctl(fd, NBD_DO_IT) < 0)
> return 1;
> return 0;
> }
>
> When signal interrupt nbd_start_device_ioctl() waiting the condition
> atomic_read(&config->recv_threads) == 0, the task can hung because it
> waits the completion of the inflight IOs.
>
> This patch fixes the issue by clearing queue, not just shutdown, when
> signal interrupt nbd_start_device_ioctl().
>
> Link: https://syzkaller.appspot.com/bug?id=7d89a3ffacd2b83fdd39549bc4d8e0a89ef21239 [1]
> Reported-by: syzbot+38e6c55d4969a14c1534@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Thanks,
Josef
