rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=0a5c/1/0x4000000000000000 softirq=16863/16865 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5868/1:b..l P5959/1:b..l
rcu: 	(detected by 1, t=10506 jiffies, g=8481, q=161 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6047 Comm: syz.0.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:do_raw_spin_lock+0x36/0x290 kernel/locking/spinlock_debug.c:114
Code: 41 55 41 54 53 48 83 e4 e0 48 81 ec 80 00 00 00 48 89 fb 65 48 8b 05 29 d8 02 11 48 89 44 24 60 49 bf 00 00 00 00 00 fc ff df <48> c7 44 24 20 b3 8a b5 41 48 c7 44 24 28 59 4a b0 8d 48 c7 44 24
RSP: 0018:ffffc900000077c0 EFLAGS: 00000086
RAX: 8a106b9edb7d9000 RBX: ffff88804b027a80 RCX: 8a106b9edb7d9000
RDX: 0000000000000000 RSI: ffffffff8dbaa5db RDI: ffff88804b027a80
RBP: ffffc90000007870 R08: 0000000000000000 R09: ffffffff81adabcb
R10: dffffc0000000000 R11: ffffed1009604f51 R12: dffffc0000000000
R13: ffff88804b027b00 R14: 0000000000000802 R15: dffffc0000000000
FS:  00007f06ad7cc6c0(0000) GS:ffff8880b8611000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0be5ba4e68 CR3: 000000010dc1a000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162
 lock_hrtimer_base kernel/time/hrtimer.c:171 [inline]
 hrtimer_try_to_cancel+0x22b/0x420 kernel/time/hrtimer.c:1362
 hrtimer_cancel+0x3b/0x50 kernel/time/hrtimer.c:1488
 perf_swevent_cancel_hrtimer kernel/events/core.c:11817 [inline]
 cpu_clock_event_stop+0xd9/0x130 kernel/events/core.c:11867
 __perf_event_overflow+0x580/0xe40 kernel/events/core.c:10333
 perf_swevent_hrtimer+0x3c5/0x550 kernel/events/core.c:11773
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x4e0/0xc60 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 6b c0 49 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 23 65 12 f6 65 8b 05 6c 41 23 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc900034efaa0 EFLAGS: 00000206
RAX: 8a106b9edb7d9000 RBX: 0000000000000a02 RCX: 8a106b9edb7d9000
RDX: 0000000000000000 RSI: ffffffff8d9baf27 RDI: 0000000000000001
RBP: ffffc900034efb28 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: fffffbfff1f476a7 R12: dffffc0000000000
R13: 0000000000000001 R14: ffff888108f2e050 R15: 1ffff9200069df54
 class_raw_spinlock_irqsave_destructor include/linux/spinlock.h:557 [inline]
 try_to_wake_up+0x7b7/0x12b0 kernel/sched/core.c:4216
 wake_up_process kernel/sched/core.c:4459 [inline]
 wake_up_q+0x85/0xd0 kernel/sched/core.c:1084
 futex_wake+0x4a0/0x560 kernel/futex/waitwake.c:198
 do_futex+0x395/0x420 kernel/futex/syscalls.c:107
 __do_sys_futex kernel/futex/syscalls.c:179 [inline]
 __se_sys_futex+0x36f/0x400 kernel/futex/syscalls.c:160
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f06ac98ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f06ad7cc0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f06acbd5fa8 RCX: 00007f06ac98ec29
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f06acbd5fac
RBP: 00007f06acbd5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f06acbd6038 R14: 00007ffed969b390 R15: 00007ffed969b478
 </TASK>
task:syz-executor    state:R  running task     stack:20472 pid:5959  tgid:5959  ppid:5958   task_flags:0x400140 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7145
 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7169
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 wp_page_copy mm/memory.c:3653 [inline]
 do_wp_page+0x1d1d/0x5800 mm/memory.c:4013
 handle_pte_fault mm/memory.c:6068 [inline]
 __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f0be5966e60
RSP: 002b:00007ffe7fe3dde8 EFLAGS: 00010296
RAX: 66007265746c6966 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 00007f0be5ba4e68 RSI: 00007f0be5a13230 RDI: 00007f0be5ba4e68
RBP: 0000000000000000 R08: fefefefefefefeff R09: ff00000000000000
R10: 00007f0be5ba2608 R11: 0000000000000206 R12: 00007f0be5a13228
R13: 00007f0be5ba7020 R14: 00007f0be5ba4e68 R15: 00007f0be5ba4e60
 </TASK>
task:udevd           state:R  running task     stack:26416 pid:5868  tgid:5868  ppid:5299   task_flags:0x400140 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7145
 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7169
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 fast_dput+0x233/0x430 fs/dcache.c:-1
 dput+0xe8/0x2b0 fs/dcache.c:905
 shmem_unlink+0x1fd/0x2d0 mm/shmem.c:4042
 vfs_unlink+0x394/0x650 fs/namei.c:4586
 do_unlinkat+0x345/0x560 fs/namei.c:4650
 __do_sys_unlink fs/namei.c:4696 [inline]
 __se_sys_unlink fs/namei.c:4694 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4694
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f794db17da7
RSP: 002b:00007ffebd58d368 EFLAGS: 00000202 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00005587528ec120 RCX: 00007f794db17da7
RDX: 00007ffebd58d38a RSI: 00005587528d04cd RDI: 00007ffebd58d378
RBP: 000055877fc3bd60 R08: 0000000000000000 R09: 00007ffebd58cce8
R10: 0000000000000010 R11: 0000000000000202 R12: 0000000000000041
R13: 00007ffebd58d378 R14: 0000000003938700 R15: 00005587528ec160
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g8481 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27432 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 6046 Comm: syz.0.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_single+0x3a9/0x590 kernel/smp.c:687
Code: 33 44 89 f6 83 e6 01 31 ff e8 83 7a 0b 00 41 83 e6 01 75 11 e8 38 76 0b 00 4d 89 fe eb 3f e8 2e 76 0b 00 eb 3c 4d 89 fe f3 90 <43> 0f b6 04 2c 84 c0 75 0f f7 03 01 00 00 00 74 1d e8 11 76 0b 00
RSP: 0018:ffffc9000295fa40 EFLAGS: 00000293
RAX: ffffffff81b44f8f RBX: ffffc9000295fa88 RCX: ffff888108f2d640
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000295fb30 R08: ffffffff8fa3b537 R09: 1ffffffff1f476a6
R10: dffffc0000000000 R11: ffffffff81706100 R12: 1ffff9200052bf51
R13: dffffc0000000000 R14: 1ffff9200052bf4c R15: 1ffff9200052bf4c
FS:  00005555792f5500(0000) GS:ffff8881a3c11000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31163fff CR3: 000000010dc1a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 task_function_call kernel/events/core.c:121 [inline]
 event_function_call+0x326/0x970 kernel/events/core.c:341
 perf_event_release_kernel+0x15d/0x510 kernel/events/core.c:5801
 perf_release+0x38/0x50 kernel/events/core.c:5876
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f06ac98ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffed969b5d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00000000000100ac RCX: 00007f06ac98ec29
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f06acbd7da0 R08: 0000000000000001 R09: 00000003d969b8cf
R10: 0000001b30520000 R11: 0000000000000246 R12: 00007f06acbd5fac
R13: 00007f06acbd5fa0 R14: ffffffffffffffff R15: 00007ffed969b6f0
 </TASK>
