======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc1-syzkaller-00081-gbb066fe812d6 #0 Not tainted
------------------------------------------------------
syz.9.4611/21131 is trying to acquire lock:
ffffffff8fef67e8 (rtnl_mutex){+.+.}-{4:4}, at: smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1908

but task is already holding lock:
ffff88806d9d8258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1624 [inline]
ffff88806d9d8258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xd5/0x760 net/smc/af_smc.c:1644

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3645
       lock_sock include/net/sock.h:1624 [inline]
       sockopt_lock_sock net/core/sock.c:1133 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1124
       do_ipv6_setsockopt+0x2160/0x4520 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:993
       udpv6_setsockopt+0x7d/0xd0 net/ipv6/udp.c:1850
       do_sock_setsockopt+0x225/0x480 net/socket.c:2298
       __sys_setsockopt+0x1a0/0x230 net/socket.c:2323
       __do_sys_setsockopt net/socket.c:2329 [inline]
       __se_sys_setsockopt net/socket.c:2326 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2326
       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){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain kernel/locking/lockdep.c:3906 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
       smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1908
       __smc_connect+0x44d/0x4890 net/smc/af_smc.c:1520
       smc_connect+0x2fc/0x760 net/smc/af_smc.c:1696
       __sys_connect_file+0x141/0x1a0 net/socket.c:2040
       __sys_connect+0x14f/0x170 net/socket.c:2059
       __do_sys_connect net/socket.c:2065 [inline]
       __se_sys_connect net/socket.c:2062 [inline]
       __x64_sys_connect+0x72/0xb0 net/socket.c:2062
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET6);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_INET6);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz.9.4611/21131:
 #0: ffff88806d9d8258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1624 [inline]
 #0: ffff88806d9d8258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xd5/0x760 net/smc/af_smc.c:1644

stack backtrace:
CPU: 1 UID: 0 PID: 21131 Comm: syz.9.4611 Not tainted 6.14.0-rc1-syzkaller-00081-gbb066fe812d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain kernel/locking/lockdep.c:3906 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
 smc_vlan_by_tcpsk+0x251/0x620 net/smc/smc_core.c:1908
 __smc_connect+0x44d/0x4890 net/smc/af_smc.c:1520
 smc_connect+0x2fc/0x760 net/smc/af_smc.c:1696
 __sys_connect_file+0x141/0x1a0 net/socket.c:2040
 __sys_connect+0x14f/0x170 net/socket.c:2059
 __do_sys_connect net/socket.c:2065 [inline]
 __se_sys_connect net/socket.c:2062 [inline]
 __x64_sys_connect+0x72/0xb0 net/socket.c:2062
 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
RIP: 0033:0x7f634cb8cde9
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:00007f634d90c038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f634cda5fa0 RCX: 00007f634cb8cde9
RDX: 000000000000001c RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f634cc0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f634cda5fa0 R15: 00007fff1894b4a8
 </TASK>