Hi developers: We may found a bug in smc module which can lead to deadlock recently. HEAD commit: 819837584309 6.12.0-rc5 git tree: upstream kernel config: https://drive.google.com/file/d/1-9pltE-1CMgGgNFu9o5l0BlCHk3Rnzb_/view?usp=sharing console output: https://drive.google.com/file/d/1uH0RDdftVIq_Boa6YWowLj3WujqVBuL7/view?usp=sharing syz repro: https://drive.google.com/file/d/1WUjiYSMebSZ7fR0uxrGx-kDLrf1v_Nra/view?usp=sharing C reproducer: https://drive.google.com/file/d/1_lB5_uacVnfDNE8VpuiY-NxEtDdzJ0Z8/view?usp=sharing Environment: Ubuntu 22.04 on Linux 5.15 QEMU emulator version 6.2.0 qemu-system-x86_64 \ -m 2G \ -smp 2 \ -kernel /home/wd/bzImage \ -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0" \ -drive file=/home/wd/bullseye.img,format=raw \ -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10021-:22 \ -net nic,model=e1000 \ -enable-kvm \ -nographic \ -pidfile vm.pid \ 2>&1 | tee vm.log If you fix this issue, please add the following tag to the commit: Reported-by: Shihao Jiang<sh.jiang@xxxxxxxxxx> ====================================================== WARNING: possible circular locking dependency detected 6.12.0-rc5 #1 Tainted: G W ------------------------------------------------------ syz-executor351/9413 is trying to acquire lock: ffff88804bd68aa8 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:902 but task is already holding lock: ffff88804bd68258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1611 [inline] ffff88804bd68258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_setsockopt+0x323/0xc10 net/smc/af_smc.c:3077 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (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+0x54/0x70 net/core/sock.c:1125 do_ipv6_setsockopt+0x2509/0x48b0 net/ipv6/ipv6_sockglue.c:567 ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:993 rawv6_setsockopt+0xd7/0x700 net/ipv6/raw.c:1054 do_sock_setsockopt+0x227/0x480 net/socket.c:2334 __sys_setsockopt+0x1a6/0x270 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+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (rtnl_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 do_ip_setsockopt+0x18a1/0x3780 net/ipv4/ip_sockglue.c:1077 ip_setsockopt+0x59/0xf0 net/ipv4/ip_sockglue.c:1417 tcp_setsockopt+0xa9/0x110 net/ipv4/tcp.c:4029 smc_setsockopt+0x1b1/0xc10 net/smc/af_smc.c:3064 do_sock_setsockopt+0x227/0x480 net/socket.c:2334 __sys_setsockopt+0x1a6/0x270 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+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&smc->clcsock_release_lock){+.+.}-{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+0x2425/0x3b90 kernel/locking/lockdep.c:5202 lock_acquire.part.0+0x11b/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:902 smc_setsockopt+0x809/0xc10 net/smc/af_smc.c:3087 do_sock_setsockopt+0x227/0x480 net/socket.c:2334 __sys_setsockopt+0x1a6/0x270 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+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &smc->clcsock_release_lock --> rtnl_mutex --> sk_lock-AF_INET6 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_INET6); lock(rtnl_mutex); lock(sk_lock-AF_INET6); lock(&smc->clcsock_release_lock); *** DEADLOCK *** 1 lock held by syz-executor351/9413: #0: ffff88804bd68258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1611 [inline] #0: ffff88804bd68258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_setsockopt+0x323/0xc10 net/smc/af_smc.c:3077 stack backtrace: CPU: 1 UID: 0 PID: 9413 Comm: syz-executor351 Tainted: G W 6.12.0-rc5 #1 Tainted: [W]=WARN Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120 print_circular_bug+0x406/0x5c0 kernel/locking/lockdep.c:2074 check_noncircular+0x2f7/0x3e0 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+0x2425/0x3b90 kernel/locking/lockdep.c:5202 lock_acquire.part.0+0x11b/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x147/0x930 kernel/locking/mutex.c:752 smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:902 smc_setsockopt+0x809/0xc10 net/smc/af_smc.c:3087 do_sock_setsockopt+0x227/0x480 net/socket.c:2334 __sys_setsockopt+0x1a6/0x270 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+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8d96fc304d Code: 28 c3 e8 46 1e 00 00 66 0f 1f 44 00 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffef30e0218 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007ffef30e0418 RCX: 00007f8d96fc304d RDX: 0000000000000017 RSI: 0000000000000029 RDI: 0000000000000005 RBP: 0000000000000001 R08: 0000000000000004 R09: 00007ffef30e0418 R10: 00000000200000c0 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffef30e0408 R14: 00007f8d97040530 R15: 0000000000000001 </TASK> ====================================================== Best Regards, Shihao
