syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/4416 is trying to acquire lock:
ffff888020669458 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: __flush_work+0x10d/0xae0 kernel/workqueue.c:3072

but task is already holding lock:
ffff888020668130 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x251/0x530 net/smc/af_smc.c:-1

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_SMC/1){+.+.}-{0:0}:
       lock_sock_nested+0x44/0x100 net/core/sock.c:3496
       smc_listen_out+0x109/0x3d0 net/smc/af_smc.c:1865
       smc_listen_out_connected net/smc/af_smc.c:1885 [inline]
       smc_listen_decline net/smc/af_smc.c:1920 [inline]
       smc_listen_work+0x581/0xd70 net/smc/af_smc.c:2463
       process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
       worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
       kthread+0x29d/0x330 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #0 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       __flush_work+0x126/0xae0 kernel/workqueue.c:3072
       __cancel_work_timer+0x3f4/0x560 kernel/workqueue.c:3163
       smc_clcsock_release+0x5c/0xe0 net/smc/smc_close.c:29
       __smc_release+0x661/0x7d0 net/smc/af_smc.c:300
       smc_close_non_accepted+0xd1/0x1f0 net/smc/af_smc.c:1798
       smc_close_cleanup_listen net/smc/smc_close.c:45 [inline]
       smc_close_active+0xb00/0xea0 net/smc/smc_close.c:225
       __smc_release+0x8d/0x7d0 net/smc/af_smc.c:276
       smc_release+0x2ca/0x530 net/smc/af_smc.c:343
       __sock_release net/socket.c:654 [inline]
       sock_close+0xd5/0x240 net/socket.c:1399
       __fput+0x22c/0x920 fs/file_table.c:320
       task_work_run+0x1d0/0x260 kernel/task_work.c:203
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_SMC/1);
                               lock((work_completion)(&new_smc->smc_listen_work));
                               lock(sk_lock-AF_SMC/1);
  lock((work_completion)(&new_smc->smc_listen_work));

 *** DEADLOCK ***

2 locks held by syz.0.17/4416:
 #0: ffff888068fe5010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff888068fe5010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline]
 #0: ffff888068fe5010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x90/0x240 net/socket.c:1399
 #1: ffff888020668130 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x251/0x530 net/smc/af_smc.c:-1

stack backtrace:
CPU: 1 PID: 4416 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __flush_work+0x126/0xae0 kernel/workqueue.c:3072
 __cancel_work_timer+0x3f4/0x560 kernel/workqueue.c:3163
 smc_clcsock_release+0x5c/0xe0 net/smc/smc_close.c:29
 __smc_release+0x661/0x7d0 net/smc/af_smc.c:300
 smc_close_non_accepted+0xd1/0x1f0 net/smc/af_smc.c:1798
 smc_close_cleanup_listen net/smc/smc_close.c:45 [inline]
 smc_close_active+0xb00/0xea0 net/smc/smc_close.c:225
 __smc_release+0x8d/0x7d0 net/smc/af_smc.c:276
 smc_release+0x2ca/0x530 net/smc/af_smc.c:343
 __sock_release net/socket.c:654 [inline]
 sock_close+0xd5/0x240 net/socket.c:1399
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4c5599c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc826fbb98 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffc826fbc80 RCX: 00007f4c5599c799
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001527e R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2d020000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4c55c15fac R14: 00007f4c55c15fa8 R15: 00007f4c55c15fa0
 </TASK>