bisecting fixing commit since 4010a528219e01dd02e768b22168f7f0e78365ce building syzkaller on 9a4781d43abfb86fe8521cb6fb084519e237454c testing commit 4010a528219e01dd02e768b22168f7f0e78365ce compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 4546cfc74d6c49c924e1cc7674d51f4639580beaed6f278ef56d82538a8a2402 run #0: crashed: BUG: sleeping function called from invalid context in lock_sock_nested run #1: crashed: possible deadlock in vmci_qp_broker_detach run #2: crashed: BUG: sleeping function called from invalid context in lock_sock_nested 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 run #10: crashed: possible deadlock in vmci_qp_broker_detach run #11: OK run #12: OK run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK testing current HEAD 4c388a8e740d3235a194f330c8ef327deef710f6 testing commit 4c388a8e740d3235a194f330c8ef327deef710f6 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 6ada571136b0dabe2bce58aaf010891b942d9232e83c03b4e2f725c311d37e3a run #0: crashed: possible deadlock in vmci_qp_broker_detach run #1: crashed: possible deadlock in vmci_qp_broker_detach run #2: crashed: possible deadlock in vmci_qp_broker_detach run #3: OK run #4: OK run #5: OK run #6: OK run #7: OK run #8: OK run #9: OK reproducer seems to be flaky Reproducer flagged being flaky revisions tested: 2, total time: 32m27.547729151s (build: 13m34.071909166s, test: 18m8.279210925s) the crash still happens on HEAD commit msg: Merge tag 'zstd-for-linus-5.16-rc1' of git://github.com/terrelln/linux crash: possible deadlock in vmci_qp_broker_detach ============================================ WARNING: possible recursive locking detected 5.16.0-rc1-syzkaller #0 Not tainted -------------------------------------------- syz-executor.3/29779 is trying to acquire lock: ffffffff8b686e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1390 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 but task is already holding lock: ffffffff8b686e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1390 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.3/29779: #0: ffffffff8b686e58 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0x11a/0x1390 drivers/misc/vmw_vmci/vmci_queue_pair.c:2093 stack backtrace: CPU: 1 PID: 29779 Comm: syz-executor.3 Not tainted 5.16.0-rc1-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:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire.cold+0x229/0x3ab kernel/locking/lockdep.c:5027 lock_acquire kernel/locking/lockdep.c:5637 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602 __mutex_lock_common kernel/locking/mutex.c:607 [inline] __mutex_lock+0x12f/0x12f0 kernel/locking/mutex.c:740 vmci_qp_broker_detach+0x11a/0x1390 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+0x85d/0x1390 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+0x204/0x8d0 fs/file_table.c:280 task_work_run+0xc0/0x160 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4193fb 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:0000000000a9fb80 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004193fb RDX: 0000000000570608 RSI: 0000000000000080 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000570420 R10: 0000000000a9fc70 R11: 0000000000000293 R12: 0000000000052122 R13: 00000000000003e8 R14: 000000000056bf80 R15: 00000000000520fe