syzbot

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WARNING: possible circular locking dependency detected
6.14.0-rc7-syzkaller-ga2392f333575 #0 Not tainted
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syz-executor365/6438 is trying to acquire lock:
ffff0000dc410aa8 (&smc->clcsock_release_lock){+.+.}-{4:4}, at: smc_switch_to_fallback+0x48/0xa7c net/smc/af_smc.c:903

but task is already holding lock:
ffff0000dc410258 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1624 [inline]
ffff0000dc410258 (sk_lock-AF_INET){+.+.}-{0:0}, at: smc_sendmsg+0x60/0x9f8 net/smc/af_smc.c:2775

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested net/core/sock.c:3662 [inline]
       lock_sock include/net/sock.h:1624 [inline]
       sockopt_lock_sock+0x88/0x148 net/core/sock.c:1133
       do_ip_setsockopt+0x138c/0x32c0 net/ipv4/ip_sockglue.c:1078
       ip_setsockopt+0x80/0x128 net/ipv4/ip_sockglue.c:1417
       raw_setsockopt+0xfc/0x290 net/ipv4/raw.c:845
       sock_common_setsockopt+0xb0/0xcc net/core/sock.c:3854
       do_sock_setsockopt+0x2a0/0x4e0 net/socket.c:2303
       __sys_setsockopt net/socket.c:2328 [inline]
       __do_sys_setsockopt net/socket.c:2334 [inline]
       __se_sys_setsockopt net/socket.c:2331 [inline]
       __arm64_sys_setsockopt+0x170/0x1e0 net/socket.c:2331
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #1 (rtnl_mutex){+.+.}-{4:4}:
       __mutex_lock_common+0x1f0/0x24b8 kernel/locking/mutex.c:585
       __mutex_lock kernel/locking/mutex.c:730 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:782
       rtnl_lock+0x20/0x2c net/core/rtnetlink.c:79
       start_sync_thread+0xe0/0x24bc net/netfilter/ipvs/ip_vs_sync.c:1761
       do_ip_vs_set_ctl+0x550/0xd70 net/netfilter/ipvs/ip_vs_ctl.c:2732
       nf_setsockopt+0x270/0x290 net/netfilter/nf_sockopt.c:101
       ip_setsockopt+0x118/0x128 net/ipv4/ip_sockglue.c:1424
       tcp_setsockopt+0xcc/0xe8 net/ipv4/tcp.c:4043
       sock_common_setsockopt+0xb0/0xcc net/core/sock.c:3854
       smc_setsockopt+0x1f8/0xd0c net/smc/af_smc.c:3081
       do_sock_setsockopt+0x2a0/0x4e0 net/socket.c:2303
       __sys_setsockopt net/socket.c:2328 [inline]
       __do_sys_setsockopt net/socket.c:2334 [inline]
       __se_sys_setsockopt net/socket.c:2331 [inline]
       __arm64_sys_setsockopt+0x170/0x1e0 net/socket.c:2331
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

-> #0 (&smc->clcsock_release_lock){+.+.}-{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+0x34f0/0x7904 kernel/locking/lockdep.c:5228
       lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5851
       __mutex_lock_common+0x1f0/0x24b8 kernel/locking/mutex.c:585
       __mutex_lock kernel/locking/mutex.c:730 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:782
       smc_switch_to_fallback+0x48/0xa7c net/smc/af_smc.c:903
       smc_sendmsg+0xfc/0x9f8 net/smc/af_smc.c:2781
       sock_sendmsg_nosec net/socket.c:718 [inline]
       __sock_sendmsg net/socket.c:733 [inline]
       __sys_sendto+0x360/0x4d8 net/socket.c:2187
       __do_sys_sendto net/socket.c:2194 [inline]
       __se_sys_sendto net/socket.c:2190 [inline]
       __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2190
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
       el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz-executor365/6438:
 #0: ffff0000dc410258 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1624 [inline]
 #0: ffff0000dc410258 (sk_lock-AF_INET){+.+.}-{0:0}, at: smc_sendmsg+0x60/0x9f8 net/smc/af_smc.c:2775

stack backtrace:
CPU: 0 UID: 0 PID: 6438 Comm: syz-executor365 Not tainted 6.14.0-rc7-syzkaller-ga2392f333575 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x154/0x1c0 kernel/locking/lockdep.c:2076
 check_noncircular+0x310/0x404 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+0x34f0/0x7904 kernel/locking/lockdep.c:5228
 lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5851
 __mutex_lock_common+0x1f0/0x24b8 kernel/locking/mutex.c:585
 __mutex_lock kernel/locking/mutex.c:730 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:782
 smc_switch_to_fallback+0x48/0xa7c net/smc/af_smc.c:903
 smc_sendmsg+0xfc/0x9f8 net/smc/af_smc.c:2781
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:733 [inline]
 __sys_sendto+0x360/0x4d8 net/socket.c:2187
 __do_sys_sendto net/socket.c:2194 [inline]
 __se_sys_sendto net/socket.c:2190 [inline]
 __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2190
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600