Re: [syzbot] WARNING: locking bug in inet_autobind

From: Felix Kuehling
Date: Tue Jan 03 2023 - 11:20:46 EST


Am 2023-01-03 um 11:05 schrieb Waiman Long:
On 1/3/23 10:39, Felix Kuehling wrote:
The regression point doesn't make sense. The kernel config doesn't enable CONFIG_DRM_AMDGPU, so there is no way that a change in AMDGPU could have caused this regression.

I agree. It is likely a pre-existing problem or caused by another commit that got triggered because of the change in cacheline alignment caused by commit c0d9271ecbd ("drm/amdgpu: Delete user queue doorbell variable").
I don't think the change can affect cache line alignment. The entire amdgpu driver doesn't even get compiled in the kernel config that was used, and the change doesn't touch any files outside drivers/gpu/drm/amd/amdgpu:

# CONFIG_DRM_AMDGPU is not set

My guess would be that it's an intermittent bug that is confusing bisect.

Regards,
  Felix



Cheers,
Longman


Regards,
  Felix


Am 2022-12-29 um 01:26 schrieb syzbot:
syzbot has found a reproducer for the following issue on:

HEAD commit:    1b929c02afd3 Linux 6.2-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145c6a68480000
kernel config: https://syzkaller.appspot.com/x/.config?x=2651619a26b4d687
dashboard link: https://syzkaller.appspot.com/bug?extid=94cc2a66fc228b23f360
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13e13e32480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13790f08480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d1849f1ca322/disk-1b929c02.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/924cb8aa4ada/vmlinux-1b929c02.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c7330dae0a0/bzImage-1b929c02.xz

The issue was bisected to:

commit c0d9271ecbd891cdeb0fad1edcdd99ee717a655f
Author: Yong Zhao <Yong.Zhao@xxxxxxx>
Date:   Fri Feb 1 23:36:21 2019 +0000

     drm/amdgpu: Delete user queue doorbell variables

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1433ece4a00000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1633ece4a00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1233ece4a00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+94cc2a66fc228b23f360@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: c0d9271ecbd8 ("drm/amdgpu: Delete user queue doorbell variables")

------------[ cut here ]------------
Looking for class "l2tp_sock" with key l2tp_socket_class, but found a different class "slock-AF_INET6" with the same key
WARNING: CPU: 0 PID: 7280 at kernel/locking/lockdep.c:937 look_up_lock_class+0x97/0x110 kernel/locking/lockdep.c:937
Modules linked in:
CPU: 0 PID: 7280 Comm: syz-executor835 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
RIP: 0010:look_up_lock_class+0x97/0x110 kernel/locking/lockdep.c:937
Code: 17 48 81 fa e0 e5 f6 8f 74 59 80 3d 5d bc 57 04 00 75 50 48 c7 c7 00 4d 4c 8a 48 89 04 24 c6 05 49 bc 57 04 01 e8 a9 42 b9 ff <0f> 0b 48 8b 04 24 eb 31 9c 5a 80 e6 02 74 95 e8 45 38 02 fa 85 c0
RSP: 0018:ffffc9000b5378b8 EFLAGS: 00010082
RAX: 0000000000000000 RBX: ffffffff91c06a00 RCX: 0000000000000000
RDX: ffff8880292d0000 RSI: ffffffff8166721c RDI: fffff520016a6f09
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000201 R11: 20676e696b6f6f4c R12: 0000000000000000
R13: ffff88802a5820b0 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f1fd7a97700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000100 CR3: 0000000078ab4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  <TASK>
  register_lock_class+0xbe/0x1120 kernel/locking/lockdep.c:1289
  __lock_acquire+0x109/0x56d0 kernel/locking/lockdep.c:4934
  lock_acquire kernel/locking/lockdep.c:5668 [inline]
  lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
  _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
  spin_lock_bh include/linux/spinlock.h:355 [inline]
  lock_sock_nested+0x5f/0xf0 net/core/sock.c:3473
  lock_sock include/net/sock.h:1725 [inline]
  inet_autobind+0x1a/0x190 net/ipv4/af_inet.c:177
  inet_send_prepare net/ipv4/af_inet.c:813 [inline]
  inet_send_prepare+0x325/0x4e0 net/ipv4/af_inet.c:807
  inet6_sendmsg+0x43/0xe0 net/ipv6/af_inet6.c:655
  sock_sendmsg_nosec net/socket.c:714 [inline]
  sock_sendmsg+0xd3/0x120 net/socket.c:734
  __sys_sendto+0x23a/0x340 net/socket.c:2117
  __do_sys_sendto net/socket.c:2129 [inline]
  __se_sys_sendto net/socket.c:2125 [inline]
  __x64_sys_sendto+0xe1/0x1b0 net/socket.c:2125
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f1fd78538b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1fd7a971f8 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f1fd78f0038 RCX: 00007f1fd78538b9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f1fd78f0030 R08: 0000000020000100 R09: 000000000000001c
R10: 0000000004008000 R11: 0000000000000212 R12: 00007f1fd78f003c
R13: 00007f1fd79ffc8f R14: 00007f1fd7a97300 R15: 0000000000022000
  </TASK>