bisecting fixing commit since d888c83fcec75194a8a48ccd283953bdba7b2550 building syzkaller on 42718dd659525414aa0bf2794688ac94a32f7764 testing commit d888c83fcec75194a8a48ccd283953bdba7b2550 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 626d838134f523ae4eaea1c4607ff74f9a9e12df89b846bb89ca8d7b659cbdd8 run #0: crashed: SYZFAIL: wrong response packet run #1: crashed: SYZFAIL: wrong response packet run #2: crashed: INFO: task hung in lock_sock_nested run #3: crashed: INFO: task hung in lock_sock_nested run #4: crashed: INFO: task hung in lock_sock_nested run #5: crashed: INFO: task hung in lock_sock_nested run #6: crashed: INFO: task hung in lock_sock_nested run #7: crashed: INFO: task hung in lock_sock_nested run #8: crashed: INFO: task hung in lock_sock_nested run #9: crashed: INFO: task hung in lock_sock_nested run #10: crashed: INFO: task hung in lock_sock_nested run #11: crashed: INFO: task hung in lock_sock_nested run #12: crashed: INFO: task hung in lock_sock_nested run #13: crashed: INFO: task hung in lock_sock_nested run #14: crashed: INFO: task hung in lock_sock_nested run #15: crashed: INFO: task hung in lock_sock_nested run #16: crashed: INFO: task hung in lock_sock_nested run #17: crashed: INFO: task hung in lock_sock_nested run #18: crashed: INFO: task hung in lock_sock_nested run #19: crashed: INFO: task hung in lock_sock_nested testing current HEAD 3e71713c9e75c34fc03f55ea86b381856ca952ee testing commit 3e71713c9e75c34fc03f55ea86b381856ca952ee compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 92a4fb52a580cfca895a902914a35140198c3862cecf2069fb4bb88c8e3329df all runs: crashed: possible deadlock in rfcomm_sk_state_change revisions tested: 2, total time: 20m35.470023336s (build: 12m0.434064371s, test: 8m2.313054686s) the crash still happens on HEAD commit msg: Merge tag 'perf-tools-fixes-for-v5.18-2022-04-29' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux crash: possible deadlock in rfcomm_sk_state_change ============================================ WARNING: possible recursive locking detected 5.18.0-rc4-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/4033 is trying to acquire lock: ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1682 [inline] ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x99/0x320 net/bluetooth/rfcomm/sock.c:73 but task is already holding lock: ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1682 [inline] ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_shutdown+0x41/0x1b0 net/bluetooth/rfcomm/sock.c:902 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM); lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by syz-executor.0/4033: #0: ffff888074872c10 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:748 [inline] #0: ffff888074872c10 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: __sock_release+0x76/0x270 net/socket.c:649 #1: ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1682 [inline] #1: ffff88801a0fd130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_shutdown+0x41/0x1b0 net/bluetooth/rfcomm/sock.c:902 #2: ffffffff8c6741c8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x25/0x200 net/bluetooth/rfcomm/core.c:507 #3: ffff88806a4fbd28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0xff/0x770 net/bluetooth/rfcomm/core.c:487 stack backtrace: CPU: 1 PID: 4033 Comm: syz-executor.0 Not tainted 5.18.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2958 [inline] check_deadlock kernel/locking/lockdep.c:3001 [inline] validate_chain kernel/locking/lockdep.c:3790 [inline] __lock_acquire.cold+0x149/0x399 kernel/locking/lockdep.c:5029 lock_acquire kernel/locking/lockdep.c:5641 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606 lock_sock_nested+0x2b/0xd0 net/core/sock.c:3312 lock_sock include/net/sock.h:1682 [inline] rfcomm_sk_state_change+0x99/0x320 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x153/0x770 net/bluetooth/rfcomm/core.c:489 rfcomm_dlc_close+0x1a4/0x200 net/bluetooth/rfcomm/core.c:520 __rfcomm_sock_close+0x80/0x1f0 net/bluetooth/rfcomm/sock.c:220 rfcomm_sock_shutdown+0xb9/0x1b0 net/bluetooth/rfcomm/sock.c:905 rfcomm_sock_release+0x4a/0x120 net/bluetooth/rfcomm/sock.c:925 __sock_release+0xbb/0x270 net/socket.c:650 sock_close+0xf/0x20 net/socket.c:1318 __fput+0x1f5/0x8c0 fs/file_table.c:317 task_work_run+0xc0/0x160 kernel/task_work.c:164 get_signal+0x19b/0x1db0 kernel/signal.c:2641 arch_do_signal_or_restart+0x88/0x1a10 arch/x86/kernel/signal.c:867 exit_to_user_mode_loop kernel/entry/common.c:166 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0261489049 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0262694168 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: fffffffffffffffc RBX: 00007f026159bf60 RCX: 00007f0261489049 RDX: 000000000000005a RSI: 0000000020000000 RDI: 0000000000000004 RBP: 00007f02614e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffda25e5c9f R14: 00007f0262694300 R15: 0000000000022000