====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.367/7488 is trying to acquire lock: ffff8880b8923d90 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline] ffff8880b8923d90 ((softirq_ctrl.lock)){+.+.}-{3:3}, at: __local_bh_disable_ip+0x264/0x400 kernel/softirq.c:168 but task is already holding lock: ffffffff8efa6548 (smc_v4_hashinfo.lock){++.+}-{3:3}, at: read_lock include/linux/rwlock_rt.h:37 [inline] ffffffff8efa6548 (smc_v4_hashinfo.lock){++.+}-{3:3}, at: smc_diag_dump_proto+0x174/0x1fb0 net/smc/smc_diag.c:207 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (smc_v4_hashinfo.lock){++.+}-{3:3}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 rt_write_lock+0x6a/0x110 kernel/locking/spinlock_rt.c:242 write_lock_bh include/linux/rwlock_rt.h:99 [inline] smc_hash_sk+0x8f/0x2a0 net/smc/af_smc.c:193 smc_sk_init+0x5a1/0x7f0 net/smc/af_smc.c:399 smc_sock_alloc net/smc/af_smc.c:420 [inline] __smc_create+0x10d/0x280 net/smc/af_smc.c:3382 __sock_create+0x4b3/0x9f0 net/socket.c:1589 sock_create net/socket.c:1647 [inline] __sys_socket_create net/socket.c:1684 [inline] __sys_socket+0xd7/0x1b0 net/socket.c:1731 __do_sys_socket net/socket.c:1745 [inline] __se_sys_socket net/socket.c:1743 [inline] __x64_sys_socket+0x7a/0x90 net/socket.c:1743 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 ((softirq_ctrl.lock)){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5385 __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5889 __local_bh_enable_ip+0x10c/0x270 kernel/softirq.c:228 local_bh_enable include/linux/bottom_half.h:33 [inline] sock_i_ino+0xa9/0xc0 net/core/sock.c:2800 smc_diag_msg_attrs_fill net/smc/smc_diag.c:68 [inline] __smc_diag_dump net/smc/smc_diag.c:98 [inline] smc_diag_dump_proto+0xa4c/0x1fb0 net/smc/smc_diag.c:217 smc_diag_dump+0x27/0xa0 net/smc/smc_diag.c:234 netlink_dump+0x6e4/0xe90 net/netlink/af_netlink.c:2327 __netlink_dump_start+0x5cb/0x7e0 net/netlink/af_netlink.c:2442 netlink_dump_start include/linux/netlink.h:341 [inline] smc_diag_handler_dump+0x178/0x210 net/smc/smc_diag.c:251 sock_diag_rcv_msg+0x4c9/0x600 net/core/sock_diag.c:-1 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x843/0xa10 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:729 ____sys_sendmsg+0x508/0x820 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(smc_v4_hashinfo.lock); lock((softirq_ctrl.lock)); lock(smc_v4_hashinfo.lock); lock((softirq_ctrl.lock)); *** DEADLOCK *** 3 locks held by syz.2.367/7488: #0: ffff888038abe908 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0 net/netlink/af_netlink.c:2406 #1: ffffffff8efa6548 (smc_v4_hashinfo.lock){++.+}-{3:3}, at: read_lock include/linux/rwlock_rt.h:37 [inline] #1: ffffffff8efa6548 (smc_v4_hashinfo.lock){++.+}-{3:3}, at: smc_diag_dump_proto+0x174/0x1fb0 net/smc/smc_diag.c:207 #2: ffffffff8d9a8b80 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8d9a8b80 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #2: ffffffff8d9a8b80 (rcu_read_lock){....}-{1:3}, at: rt_read_lock+0x1f8/0x360 kernel/locking/spinlock_rt.c:234 stack backtrace: CPU: 1 UID: 0 PID: 7488 Comm: syz.2.367 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5385 __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5889 __local_bh_enable_ip+0x10c/0x270 kernel/softirq.c:228 local_bh_enable include/linux/bottom_half.h:33 [inline] sock_i_ino+0xa9/0xc0 net/core/sock.c:2800 smc_diag_msg_attrs_fill net/smc/smc_diag.c:68 [inline] __smc_diag_dump net/smc/smc_diag.c:98 [inline] smc_diag_dump_proto+0xa4c/0x1fb0 net/smc/smc_diag.c:217 smc_diag_dump+0x27/0xa0 net/smc/smc_diag.c:234 netlink_dump+0x6e4/0xe90 net/netlink/af_netlink.c:2327 __netlink_dump_start+0x5cb/0x7e0 net/netlink/af_netlink.c:2442 netlink_dump_start include/linux/netlink.h:341 [inline] smc_diag_handler_dump+0x178/0x210 net/smc/smc_diag.c:251 sock_diag_rcv_msg+0x4c9/0x600 net/core/sock_diag.c:-1 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x843/0xa10 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:729 ____sys_sendmsg+0x508/0x820 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline] __do_sys_sendmsg net/socket.c:2705 [inline] __se_sys_sendmsg net/socket.c:2703 [inline] __x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efd3b8debe9 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:00007efd39b46038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007efd3bb05fa0 RCX: 00007efd3b8debe9 RDX: 0000000000008004 RSI: 0000200000000040 RDI: 0000000000000005 RBP: 00007efd3b961e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007efd3bb06038 R14: 00007efd3bb05fa0 R15: 00007ffdc14e8bd8