bisecting fixing commit since 6b1f86f8e9c7f9de7ca1cb987b2cf25e99b1ae3a building syzkaller on 5ff41e943946a9e71b55566a02c8b1371fc9b8de testing commit 6b1f86f8e9c7f9de7ca1cb987b2cf25e99b1ae3a compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 4929a674860504bcaf01a930b93391d691f7c6ff4df05d36d4306c39b52f13b5 run #0: basic kernel testing failed: BUG: program execution failed: executor NUM: exit status NUM run #1: crashed: INFO: task hung in vmci_qp_broker_detach run #2: crashed: INFO: task hung in vmci_qp_broker_detach run #3: crashed: INFO: task hung in vmci_qp_broker_detach run #4: crashed: INFO: task hung in vmci_qp_broker_detach run #5: crashed: INFO: task hung in vmci_qp_broker_detach run #6: crashed: INFO: task hung in vmci_qp_broker_detach run #7: crashed: INFO: task hung in vmci_qp_broker_detach run #8: crashed: INFO: task hung in vmci_qp_broker_detach run #9: crashed: INFO: task hung in vmci_qp_broker_detach run #10: crashed: INFO: task hung in vmci_qp_broker_detach run #11: crashed: INFO: task hung in vmci_qp_broker_detach run #12: crashed: INFO: task hung in vmci_qp_broker_detach run #13: crashed: INFO: task hung in vmci_qp_broker_detach run #14: crashed: INFO: task hung in vmci_qp_broker_detach run #15: crashed: INFO: task hung in vmci_qp_broker_detach run #16: crashed: INFO: task hung in vmci_qp_broker_detach run #17: crashed: INFO: task hung in vmci_qp_broker_detach run #18: crashed: INFO: task hung in vmci_qp_broker_detach run #19: crashed: INFO: task hung in vmci_qp_broker_detach testing current HEAD 4b0986a3613c92f4ec1bdc7f60ec66fea135991f testing commit 4b0986a3613c92f4ec1bdc7f60ec66fea135991f compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 2dfc4f1301e523b5921a38ecd8c39919389be9c6781641dda277c2987530992c run #0: basic kernel testing failed: BUG: program execution failed: executor NUM: exit status NUM run #1: crashed: possible deadlock in vmci_qp_broker_detach run #2: crashed: possible deadlock in vmci_qp_broker_detach run #3: crashed: possible deadlock in vmci_qp_broker_detach run #4: crashed: possible deadlock in vmci_qp_broker_detach run #5: crashed: possible deadlock in vmci_qp_broker_detach run #6: crashed: possible deadlock in vmci_qp_broker_detach run #7: crashed: possible deadlock in vmci_qp_broker_detach run #8: crashed: possible deadlock in vmci_qp_broker_detach run #9: crashed: possible deadlock in vmci_qp_broker_detach revisions tested: 2, total time: 22m3.666356749s (build: 12m0.297509548s, test: 9m32.088889101s) the crash still happens on HEAD commit msg: Linux 5.18 crash: possible deadlock in vmci_qp_broker_detach ============================================ WARNING: possible recursive locking detected 5.18.0-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/4118 is trying to acquire lock: ffffffff8b870838 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1220 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 but task is already holding lock: ffffffff8b870838 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1220 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 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-executor.0/4118: #0: ffffffff8b870838 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1220 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 stack backtrace: CPU: 0 PID: 4118 Comm: syz-executor.0 Not tainted 5.18.0-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 __mutex_lock_common kernel/locking/mutex.c:600 [inline] __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:733 vmci_qp_broker_detach+0x11a/0x1220 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 ctx_free_ctx+0x410/0xc10 drivers/misc/vmw_vmci/vmci_context.c:444 kref_put include/linux/kref.h:65 [inline] vmci_ctx_put drivers/misc/vmw_vmci/vmci_context.c:497 [inline] vmci_ctx_enqueue_datagram+0x3de/0x530 drivers/misc/vmw_vmci/vmci_context.c:360 dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:275 [inline] vmci_datagram_dispatch+0x270/0x870 drivers/misc/vmw_vmci/vmci_datagram.c:339 qp_notify_peer+0x136/0x200 drivers/misc/vmw_vmci/vmci_queue_pair.c:1479 vmci_qp_broker_detach+0x7e7/0x1220 drivers/misc/vmw_vmci/vmci_queue_pair.c:2186 ctx_free_ctx+0x410/0xc10 drivers/misc/vmw_vmci/vmci_context.c:444 vmci_host_close+0xf2/0x180 drivers/misc/vmw_vmci/vmci_host.c:143 __fput+0x1f5/0x8c0 fs/file_table.c:317 task_work_run+0xc0/0x160 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:169 [inline] exit_to_user_mode_prepare+0x23c/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: 0033:0x7f52ec03bc8b Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007fffbdd6a3a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f52ec03bc8b RDX: 0000001b33620000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00007f52ec19d960 R08: 0000000000000000 R09: 00007fffbddcf080 R10: 00007fffbddcf090 R11: 0000000000000293 R12: 0000000000014ad0 R13: 00007fffbdd6a4a0 R14: 00007fffbdd6a4c0 R15: 0000000000000032