============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.2.462/7953 is trying to acquire lock: ffffffff8f7c66b0 (qp_broker_list.mutex){+.+.}-{4:4}, at: vmci_qp_broker_detach+0x14c/0x11e0 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095 but task is already holding lock: ffffffff8f7c66b0 (qp_broker_list.mutex){+.+.}-{4:4}, at: vmci_qp_broker_detach+0x14c/0x11e0 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(qp_broker_list.mutex); lock(qp_broker_list.mutex); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz.2.462/7953: #0: ffffffff8f7c66b0 (qp_broker_list.mutex){+.+.}-{4:4}, at: vmci_qp_broker_detach+0x14c/0x11e0 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095 stack backtrace: CPU: 3 UID: 0 PID: 7953 Comm: syz.2.462 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_deadlock_bug.cold+0xbd/0xca kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x12bb/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 vmci_qp_broker_detach+0x14c/0x11e0 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095 ctx_free_ctx+0x517/0xda0 drivers/misc/vmw_vmci/vmci_context.c:424 kref_put include/linux/kref.h:65 [inline] vmci_ctx_put drivers/misc/vmw_vmci/vmci_context.c:477 [inline] vmci_ctx_enqueue_datagram+0x4be/0x5f0 drivers/misc/vmw_vmci/vmci_context.c:340 dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:276 [inline] vmci_datagram_dispatch+0x3db/0xc60 drivers/misc/vmw_vmci/vmci_datagram.c:340 qp_notify_peer+0x1a6/0x230 drivers/misc/vmw_vmci/vmci_queue_pair.c:1481 vmci_qp_broker_detach+0xa20/0x11e0 drivers/misc/vmw_vmci/vmci_queue_pair.c:2188 ctx_free_ctx+0x517/0xda0 drivers/misc/vmw_vmci/vmci_context.c:424 kref_put include/linux/kref.h:65 [inline] vmci_ctx_put drivers/misc/vmw_vmci/vmci_context.c:477 [inline] vmci_ctx_destroy+0x150/0x1c0 drivers/misc/vmw_vmci/vmci_context.c:195 vmci_host_close+0x115/0x1a0 drivers/misc/vmw_vmci/vmci_host.c:143 __fput+0x3ff/0xb50 fs/file_table.c:510 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] __do_fast_syscall_32+0x608/0x950 arch/x86/entry/syscall_32.c:310 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf709efcc Code: d2 74 05 c1 e8 0c 89 02 8b 5d fc 31 c0 c9 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 58 b8 RSP: 002b:00000000f546c50c EFLAGS: 00000292 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00000000ffffffff RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: d2 74 05 c1 shlb %cl,-0x3f(%rbp,%rax,1) 4: e8 0c 89 02 8b call 0x8b028915 9: 5d pop %rbp a: fc cld b: 31 c0 xor %eax,%eax d: c9 leave e: c3 ret f: 90 nop 10: 90 nop 11: 90 nop 12: 90 nop 13: 90 nop 14: 90 nop 15: 90 nop 16: 90 nop 17: 90 nop 18: 90 nop 19: 90 nop 1a: 90 nop 1b: 90 nop 1c: 90 nop 1d: 90 nop 1e: 0f 1f 00 nopl (%rax) 21: 51 push %rcx 22: 52 push %rdx 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 ret 2e: 90 nop 2f: 2e 8d b4 26 00 00 00 cs lea 0x0(%rsi,%riz,1),%esi 36: 00 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 3e: 58 pop %rax 3f: b8 .byte 0xb8