syzbot

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0 Not tainted
------------------------------------------------------
syz.2.244/7194 is trying to acquire lock:
ffffffff8fac5328 (rtnl_mutex){+.+.}-{3:3}, at: ipv6_sock_ac_close+0xd9/0x110 net/ipv6/anycast.c:219

but task is already holding lock:
ffff888079958aa8 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_clcsock_release+0x75/0xe0 net/smc/smc_close.c:30

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&smc->clcsock_release_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:902
       smc_setsockopt+0xa7b/0xc00 net/smc/af_smc.c:3087
       do_sock_setsockopt+0x222/0x480 net/socket.c:2334
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2357
       __do_sys_setsockopt net/socket.c:2366 [inline]
       __se_sys_setsockopt net/socket.c:2363 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2363
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3611
       lock_sock include/net/sock.h:1611 [inline]
       sockopt_lock_sock net/core/sock.c:1125 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1116
       do_ipv6_setsockopt+0x1f55/0x4800 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:993
       udpv6_setsockopt+0x7d/0xd0 net/ipv6/udp.c:1704
       do_sock_setsockopt+0x222/0x480 net/socket.c:2334
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2357
       __do_sys_setsockopt net/socket.c:2366 [inline]
       __se_sys_setsockopt net/socket.c:2363 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2363
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (rtnl_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       ipv6_sock_ac_close+0xd9/0x110 net/ipv6/anycast.c:219
       inet6_release+0x47/0x70 net/ipv6/af_inet6.c:487
       __sock_release net/socket.c:658 [inline]
       sock_release+0x8e/0x1d0 net/socket.c:686
       smc_clcsock_release+0xb7/0xe0 net/smc/smc_close.c:34
       __smc_release+0x5c2/0x880 net/smc/af_smc.c:301
       smc_release+0x1fc/0x5f0 net/smc/af_smc.c:344
       __sock_release+0xb0/0x270 net/socket.c:658
       sock_close+0x1c/0x30 net/socket.c:1426
       __fput+0x3f6/0xb60 fs/file_table.c:431
       task_work_run+0x14e/0x250 kernel/task_work.c:239
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
       exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
       __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
       syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
       do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  rtnl_mutex --> sk_lock-AF_INET6 --> &smc->clcsock_release_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&smc->clcsock_release_lock);
                               lock(sk_lock-AF_INET6);
                               lock(&smc->clcsock_release_lock);
  lock(rtnl_mutex);

 *** DEADLOCK ***

2 locks held by syz.2.244/7194:
 #0: ffff888078fb5608 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
 #0: ffff888078fb5608 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x270 net/socket.c:657
 #1: ffff888079958aa8 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_clcsock_release+0x75/0xe0 net/smc/smc_close.c:30

stack backtrace:
CPU: 0 UID: 0 PID: 7194 Comm: syz.2.244 Not tainted 6.12.0-rc6-syzkaller-00077-g2e1b3cc9d7f7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
 ipv6_sock_ac_close+0xd9/0x110 net/ipv6/anycast.c:219
 inet6_release+0x47/0x70 net/ipv6/af_inet6.c:487
 __sock_release net/socket.c:658 [inline]
 sock_release+0x8e/0x1d0 net/socket.c:686
 smc_clcsock_release+0xb7/0xe0 net/smc/smc_close.c:34
 __smc_release+0x5c2/0x880 net/smc/af_smc.c:301
 smc_release+0x1fc/0x5f0 net/smc/af_smc.c:344
 __sock_release+0xb0/0x270 net/socket.c:658
 sock_close+0x1c/0x30 net/socket.c:1426
 __fput+0x3f6/0xb60 fs/file_table.c:431
 task_work_run+0x14e/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a8837e719
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd894e9fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000027d8d RCX: 00007f3a8837e719
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f3a88537a80 R08: 0000000000000001 R09: 00007ffd894ea2df
R10: 00007f3a88200000 R11: 0000000000000246 R12: 0000000000027e31
R13: 00007ffd894ea0f0 R14: 0000000000000032 R15: ffffffffffffffff
 </TASK>