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: 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: 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: OK run #8: OK run #9: OK run #10: crashed: possible deadlock in vmci_qp_broker_detach run #11: OK run #12: OK run #13: OK run #14: OK run #15: crashed: possible deadlock in vmci_qp_broker_detach run #16: OK run #17: OK run #18: OK run #19: OK reproducer seems to be flaky testing current HEAD 8fe31e0995f048d16b378b90926793a0aa4af1e5 testing commit 8fe31e0995f048d16b378b90926793a0aa4af1e5 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: e97b9ce6b99d31b14e4f1df72ec5e19393d387813e993baef0a12a196440ce50 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: 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: OK run #8: OK run #9: OK run #10: OK run #11: OK run #12: crashed: possible deadlock in vmci_qp_broker_detach run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK Reproducer flagged being flaky revisions tested: 2, total time: 32m34.261042738s (build: 13m31.604107027s, test: 18m23.478388354s) the crash still happens on HEAD commit msg: Merge tag 'gpio-fixes-for-v5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux crash: possible deadlock in vmci_qp_broker_detach ============================================ WARNING: possible recursive locking detected 5.15.0-rc5-syzkaller #0 Not tainted -------------------------------------------- syz-executor.2/11289 is trying to acquire lock: ffffffff8b669d98 (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: ffffffff8b669d98 (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.2/11289: #0: ffffffff8b669d98 (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: 11289 Comm: syz-executor.2 Not tainted 5.15.0-rc5-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:2944 [inline] check_deadlock kernel/locking/lockdep.c:2987 [inline] validate_chain kernel/locking/lockdep.c:3776 [inline] __lock_acquire.cold+0x229/0x3ab kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 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+0x206/0x8d0 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 RA