Message-ID: <000000000000072a9f05dc09b177@google.com>
Date:   Wed, 06 Apr 2022 22:24:26 -0700
From:   syzbot <syzbot+cbb4b1ebc70d0c5a8c29@...kaller.appspotmail.com>
To:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] INFO: task hung in nbd_add_socket (2)

syzbot has found a reproducer for the following issue on:

HEAD commit:    3e732ebf7316 Merge tag 'for_linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=171d476b700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fa19d4c2766111a7
dashboard link: https://syzkaller.appspot.com/bug?extid=cbb4b1ebc70d0c5a8c29
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=17b3020f700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=125d90a7700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cbb4b1ebc70d0c5a8c29@...kaller.appspotmail.com

INFO: task syz-executor145:3630 blocked for more than 143 seconds.
      Not tainted 5.18.0-rc1-syzkaller-00016-g3e732ebf7316 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor145 state:D stack:28224 pid: 3630 ppid:  3624 flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5073 [inline]
 __schedule+0xa9a/0x4940 kernel/sched/core.c:6382
 schedule+0xd2/0x1f0 kernel/sched/core.c:6454
 blk_mq_freeze_queue_wait+0x112/0x160 block/blk-mq.c:179
 nbd_add_socket+0x166/0x810 drivers/block/nbd.c:1109
 __nbd_ioctl drivers/block/nbd.c:1454 [inline]
 nbd_ioctl+0x38c/0xb10 drivers/block/nbd.c:1511
 blkdev_ioctl+0x36e/0x800 block/ioctl.c:588
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f5f0d0f33e9
RSP: 002b:00007ffd5f102da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000000764b6 RCX: 00007f5f0d0f33e9
RDX: 0000000000000005 RSI: 000000000000ab00 RDI: 0000000000000004
RBP: 0000000000000000 R08: 00007ffd5f102f48 R09: 00007ffd5f102f48
R10: 00007ffd5f102f48 R11: 0000000000000246 R12: 00007ffd5f102dbc
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/28:
 #0: ffffffff8bd7f360 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6467
2 locks held by kworker/u4:2/50:
 #0: ffff8880b9c3a058 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:554
 #1: ffff8880b9c278c8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x3e7/0x4e0 kernel/sched/psi.c:889
2 locks held by getty/3275:
 #0: ffff888025c8d098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffffc90001bf92e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcea/0x1230 drivers/tty/n_tty.c:2075
1 lock held by udevd/3626:
 #0: ffff88801c57c118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x99/0x950 block/bdev.c:905
1 lock held by syz-executor145/3630:
 #0: ffff88801c4f5198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x151/0xb10 drivers/block/nbd.c:1504

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 5.18.0-rc1-syzkaller-00016-g3e732ebf7316 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1e6/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xc1d/0xf50 kernel/hung_task.c:369
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 50 Comm: kworker/u4:2 Not tainted 5.18.0-rc1-syzkaller-00016-g3e732ebf7316 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3696 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3716 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3771 [inline]
RIP: 0010:__lock_acquire+0x168a/0x56c0 kernel/locking/lockdep.c:5029
Code: ed 60 58 fa 8f 48 89 5c 24 10 0f 84 a6 03 00 00 48 8d 14 ed 60 58 fa 8f 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 <0f> 85 e4 2c 00 00 48 8b 1c ed 60 58 fa 8f 48 85 db 74 58 48 83 eb
RSP: 0018:ffffc90000dbf7b8 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffffffff8ffec728 RCX: ffffffff815c883e
RDX: 1ffffffff1ffd8e5 RSI: 0000000000000008 RDI: ffffffff90035900
RBP: 0000000000008dd9 R08: 0000000000000000 R09: ffffffff90035907
R10: fffffbfff2006b20 R11: 0000000000000001 R12: ffff888011c6abc0
R13: ffff888011c6a0c0 R14: 0000000000000000 R15: 623d1377ab3a24ec
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557e13d9c600 CR3: 000000000ba8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire kernel/locking/lockdep.c:5641 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606
 __mutex_lock_common kernel/locking/mutex.c:600 [inline]
 __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:733
 arch_jump_label_transform_queue+0x58/0x100 arch/x86/kernel/jump_label.c:136
 __jump_label_update+0x12e/0x400 kernel/jump_label.c:451
 jump_label_update+0x32f/0x410 kernel/jump_label.c:830
 static_key_disable_cpuslocked+0x152/0x1b0 kernel/jump_label.c:207
 static_key_disable+0x16/0x20 kernel/jump_label.c:215
 toggle_allocation_gate mm/kfence/core.c:799 [inline]
 toggle_allocation_gate+0x183/0x390 mm/kfence/core.c:777
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.077 msecs
----------------
Code disassembly (best guess), 5 bytes skipped:
   0:	48 89 5c 24 10       	mov    %rbx,0x10(%rsp)
   5:	0f 84 a6 03 00 00    	je     0x3b1
   b:	48 8d 14 ed 60 58 fa 	lea    -0x7005a7a0(,%rbp,8),%rdx
  12:	8f
  13:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1a:	fc ff df
  1d:	48 c1 ea 03          	shr    $0x3,%rdx
  21:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
* 25:	0f 85 e4 2c 00 00    	jne    0x2d0f <-- trapping instruction
  2b:	48 8b 1c ed 60 58 fa 	mov    -0x7005a7a0(,%rbp,8),%rbx
  32:	8f
  33:	48 85 db             	test   %rbx,%rbx
  36:	74 58                	je     0x90
  38:	48                   	rex.W
  39:	83                   	.byte 0x83
  3a:	eb                   	.byte 0xeb

Powered by blists - more mailing lists