On Fri, Sep 27, 2019 at 05:37:20AM +0000, Dexuan Cui wrote:
> > From: linux-hyperv-owner@xxxxxxxxxxxxxxx
> > <linux-hyperv-owner@xxxxxxxxxxxxxxx> On Behalf Of Stefano Garzarella
> > Sent: Thursday, September 26, 2019 12:48 AM
> >
> > Hi Dexuan,
> >
> > On Thu, Sep 26, 2019 at 01:11:27AM +0000, Dexuan Cui wrote:
> > > ...
> > > NOTE: I only tested the code on Hyper-V. I can not test the code for
> > > virtio socket, as I don't have a KVM host. :-( Sorry.
> > >
> > > @Stefan, @Stefano: please review & test the patch for virtio socket,
> > > and let me know if the patch breaks anything. Thanks!
> >
> > Comment below, I'll test it ASAP!
>
> Stefano, Thank you!
>
> BTW, this is how I tested the patch:
> 1. write a socket server program in the guest. The program calls listen()
> and then calls sleep(10000 seconds). Note: accept() is not called.
>
> 2. create some connections to the server program in the guest.
>
> 3. kill the server program by Ctrl+C, and "dmesg" will show the scary
> call-trace, if the kernel is built with
> CONFIG_LOCKDEP=y
> CONFIG_LOCKDEP_SUPPORT=y
>
> 4. Apply the patch, do the same test and we should no longer see the call-trace.
>
Hi Dexuan,
I tested on virtio socket and it works as expected!
With your patch applied I don't have issues and call-trace. Without
the patch I have a very similar call-trace (as expected):
============================================
WARNING: possible recursive locking detected
5.3.0-vsock #17 Not tainted
--------------------------------------------
python3/872 is trying to acquire lock:
ffff88802b650110 (sk_lock-AF_VSOCK){+.+.}, at: virtio_transport_release+0x34/0x330 [vmw_vsock_virtio_transport_common]
but task is already holding lock:
ffff88803597ce10 (sk_lock-AF_VSOCK){+.+.}, at: __vsock_release+0x3f/0x130 [vsock]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(sk_lock-AF_VSOCK);
lock(sk_lock-AF_VSOCK);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by python3/872:
#0: ffff88802c957180 (&sb->s_type->i_mutex_key#8){+.+.}, at: __sock_release+0x2d/0xb0
#1: ffff88803597ce10 (sk_lock-AF_VSOCK){+.+.}, at: __vsock_release+0x3f/0x130 [vsock]
stack backtrace:
CPU: 0 PID: 872 Comm: python3 Not tainted 5.3.0-vsock #17
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
Call Trace:
dump_stack+0x85/0xc0
__lock_acquire.cold+0xad/0x22b
lock_acquire+0xc4/0x1a0
? virtio_transport_release+0x34/0x330 [vmw_vsock_virtio_transport_common]
lock_sock_nested+0x5d/0x80
? virtio_transport_release+0x34/0x330 [vmw_vsock_virtio_transport_common]
virtio_transport_release+0x34/0x330 [vmw_vsock_virtio_transport_common]
? mark_held_locks+0x49/0x70
? _raw_spin_unlock_irqrestore+0x44/0x60
__vsock_release+0x2d/0x130 [vsock]
__vsock_release+0xb9/0x130 [vsock]
vsock_release+0x12/0x30 [vsock]
__sock_release+0x3d/0xb0
sock_close+0x14/0x20
__fput+0xc1/0x250
task_work_run+0x93/0xb0
exit_to_usermode_loop+0xd3/0xe0
syscall_return_slowpath+0x205/0x310
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Feel free to add:
Tested-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
