bisecting fixing commit since ae4b064e2a616b545acf02b8f50cc513b32c7522 building syzkaller on 08003f6440deafc4e193b159c4acece64f7864b1 testing commit ae4b064e2a616b545acf02b8f50cc513b32c7522 with gcc (GCC) 8.1.0 kernel signature: f979973e4228755793b00710a7de475dcaa966d737216490e2f81e32ee2a3604 run #0: crashed: INFO: rcu detected stall in chrdev_open run #1: crashed: INFO: rcu detected stall in chrdev_open run #2: crashed: INFO: rcu detected stall in chrdev_open run #3: crashed: INFO: rcu detected stall in corrupted run #4: crashed: INFO: rcu detected stall in chrdev_open run #5: crashed: INFO: rcu detected stall in chrdev_open run #6: crashed: INFO: rcu detected stall in chrdev_open run #7: crashed: INFO: rcu detected stall in chrdev_open run #8: crashed: INFO: rcu detected stall in chrdev_open run #9: crashed: INFO: rcu detected stall in corrupted testing current HEAD 659caaf65dc9c7150aa3e80225ec6e66b25ab3ce testing commit 659caaf65dc9c7150aa3e80225ec6e66b25ab3ce with gcc (GCC) 8.1.0 kernel signature: 7494fbc0fffc10b5721466e92be200ed9b80074b57931d40948777f150f67532 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in chrdev_open run #4: crashed: INFO: rcu detected stall in chrdev_open run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in chrdev_open revisions tested: 2, total time: 20m41.780579841s (build: 10m44.00060373s, test: 9m23.545304648s) the crash still happens on HEAD commit msg: Merge tag 'ceph-for-5.10-rc3' of git://github.com/ceph/ceph-client crash: INFO: rcu detected stall in chrdev_open rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): ------------[ cut here ]------------ WARNING: CPU: 1 PID: 8330 at kernel/sched/core.c:3009 try_invoke_on_locked_down_task+0xab/0x130 kernel/sched/core.c:3009 Modules linked in: CPU: 1 PID: 8330 Comm: syz-executor.0 Not tainted 5.10.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:try_invoke_on_locked_down_task+0xab/0x130 kernel/sched/core.c:3009 Code: d0 65 48 33 0c 25 28 00 00 00 0f 85 8f 00 00 00 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b 05 75 9c e0 7e 85 c0 75 93 <0f> 0b eb 8f 48 8d 75 c0 48 89 df 45 31 ed e8 92 c0 ff ff 8b 4b 40 RSP: 0018:ffffc90000d08dc0 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffff88810681e100 RCX: 0000000000000001 RDX: ffffc90000d08e54 RSI: ffffffff81265750 RDI: ffff88810681e100 RBP: ffffc90000d08e08 R08: 0000000000000000 R09: c0000000ffffdfff R10: ffff88810681e480 R11: ffffc90000d08bf0 R12: 000000000002ed40 R13: ffffffff843c5040 R14: ffffffff81265750 R15: ffffc90000d08e54 FS: 00007f1661138700(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000714158 CR3: 000000011ea4e000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_print_task_stall kernel/rcu/tree_stall.h:267 [inline] print_other_cpu_stall kernel/rcu/tree_stall.h:475 [inline] check_cpu_stall kernel/rcu/tree_stall.h:634 [inline] rcu_pending kernel/rcu/tree.c:3694 [inline] rcu_sched_clock_irq.cold.92+0x24b/0x53b kernel/rcu/tree.c:2567 update_process_times+0x54/0x90 kernel/time/timer.c:1709 tick_sched_handle.isra.24+0x20/0x60 kernel/time/tick-sched.c:176 tick_sched_timer+0x74/0x90 kernel/time/tick-sched.c:1328 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1e1/0x4f0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0xfc/0x210 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x93/0x2a0 arch/x86/kernel/apic/apic.c:1097 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xd5/0xf0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline] RIP: 0010:lock_acquire+0x133/0x410 kernel/locking/lockdep.c:5439 Code: b8 ff ff ff ff 65 0f c1 05 1a 8b dd 7e 83 f8 01 0f 85 d5 01 00 00 48 83 3d 11 7f 07 03 00 0f 84 e5 01 00 00 48 8b 7d 98 57 9d <0f> 1f 44 00 00 48 8b 45 d0 65 48 33 04 25 28 00 00 00 0f 85 bd 02 RSP: 0018:ffffc90004d57ad0 EFLAGS: 00000286 RAX: 0000000000000001 RBX: 0000000000000001 RCX: d27c185d29fc4082 RDX: d27c185d29fc4082 RSI: ffffffff83e7680f RDI: 0000000000000286 RBP: ffffc90004d57b38 R08: 0000000000000001 R09: 0000000000000001 R10: 00000000000059c6 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff84514c68 R15: 0000000000000000 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x94/0x9f0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 tty_open_by_driver drivers/tty/tty_io.c:1947 [inline] tty_open+0x1d3/0x4b0 drivers/tty/tty_io.c:2031 chrdev_open+0xa0/0x1d0 fs/char_dev.c:414 do_dentry_open+0x163/0x3d0 fs/open.c:817 vfs_open+0x28/0x30 fs/open.c:931 do_open fs/namei.c:3252 [inline] path_openat+0x476/0xa90 fs/namei.c:3369 do_filp_open+0x8e/0x100 fs/namei.c:3396 do_sys_openat2+0x218/0x2d0 fs/open.c:1168 do_sys_open+0x48/0x80 fs/open.c:1184 __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x1b/0x20 fs/open.c:1195 do_syscall_64+0x31/0x80 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45a989 Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f1661137c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a989 RDX: 0000000000000000 RSI: 0000000020000380 RDI: ffffffffffffff9c RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f16611386d4 R13: 00000000004c86f8 R14: 00000000004dfaa8 R15: 00000000ffffffff