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: 472fbeabda23dcd95d4936715625e40a3bec10d994b4940380ad8a816165ffda run #0: basic kernel testing failed: BUG: program execution failed: executor NUM: failed to write control pipe: write |NUM: broken pipe 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 0840a7914caa14315a3191178a9f72c742477860 testing commit 0840a7914caa14315a3191178a9f72c742477860 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: b99c7a24fe837b57c9aea787b5c03adecb6fc9e2d212bfc65137a095fedb0a0c all runs: crashed: possible deadlock in vmci_qp_broker_detach revisions tested: 2, total time: 23m14.127042705s (build: 12m47.582307895s, test: 9m45.697564754s) the crash still happens on HEAD commit msg: Merge tag 'char-misc-5.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc crash: possible deadlock in vmci_qp_broker_detach ============================================ WARNING: possible recursive locking detected 5.19.0-rc3-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/4107 is trying to acquire lock: ffffffff8b889498 (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: ffffffff8b889498 (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.0/4107: #0: ffffffff8b889498 (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: 1 PID: 4107 Comm: syz-executor.0 Not tainted 5.19.0-rc3-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:2988 [inline] check_deadlock kernel/locking/lockdep.c:3031 [inline] validate_chain kernel/locking/lockdep.c:3816 [inline] __lock_acquire.cold+0x1e0/0x3a9 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5665 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 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:177 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+0x19/0x50 kernel/entry/common.c:294 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7faa5bc3bc8b 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:00007ffea2a4f6c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007faa5bc3bc8b RDX: 0000001b33120000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00007faa5bd9d960 R08: 0000000000000000 R09: 00007ffea2aa6080 R10: 00007ffea2aa6090 R11: 0000000000000293 R12: 0000000000016721 R13: 00007ffea2a4f7c0 R14: 00007ffea2a4f7e0 R15: 0000000000000032