rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10500 ticks this GP) idle=c82/1/0x4000000000000000 softirq=34294/34294 fqs=5212 
	(t=10502 jiffies g=53797 q=4365)
NMI backtrace for cpu 0
CPU: 0 PID: 18535 Comm: syz-executor.4 Not tainted 5.13.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:341
 print_cpu_stall kernel/rcu/tree_stall.h:624 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:699 [inline]
 rcu_pending kernel/rcu/tree.c:3911 [inline]
 rcu_sched_clock_irq.cold+0x3f1/0x74b kernel/rcu/tree.c:2649
 update_process_times+0x16d/0x200 kernel/time/timer.c:1796
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1374
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1601
 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:647
RIP: 0010:__sanitizer_cov_trace_pc+0x4c/0x60 kernel/kcov.c:202
Code: 0e 85 c9 74 35 8b 82 3c 15 00 00 85 c0 74 2b 8b 82 18 15 00 00 83 f8 02 75 20 48 8b 8a 20 15 00 00 8b 92 1c 15 00 00 48 8b 01 <48> 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 c3 0f 1f 00 41 55
RSP: 0018:ffffc9000908f0d0 EFLAGS: 00000246
RAX: 000000000003ffff RBX: ffffc9000908f420 RCX: ffffc900120ef000
RDX: 0000000000040000 RSI: ffffffff8191d5df RDI: ffff8880123e3c08
RBP: ffffffff8c042520 R08: 0000000000000001 R09: ffff8880123e3c0f
R10: ffffed100247c781 R11: 0000000000000001 R12: ffffc9000908f218
R13: dffffc0000000000 R14: ffff8880123e3a20 R15: 0000000000000008
 perf_event_count kernel/events/core.c:4382 [inline]
 perf_output_read_group kernel/events/core.c:6877 [inline]
 perf_output_read+0xc0f/0x1310 kernel/events/core.c:6914
 perf_output_sample+0xd12/0x1be0 kernel/events/core.c:6961
 __perf_event_output kernel/events/core.c:7446 [inline]
 perf_event_output_forward+0x132/0x270 kernel/events/core.c:7460
 __perf_event_overflow+0x13c/0x3d0 kernel/events/core.c:9135
 perf_swevent_overflow kernel/events/core.c:9211 [inline]
 perf_swevent_event+0x347/0x550 kernel/events/core.c:9239
 do_perf_sw_event kernel/events/core.c:9352 [inline]
 ___perf_sw_event+0x31a/0x570 kernel/events/core.c:9383
 __perf_sw_event+0x54/0x130 kernel/events/core.c:9395
 perf_sw_event include/linux/perf_event.h:1170 [inline]
 mm_account_fault mm/memory.c:4608 [inline]
 handle_mm_fault+0x5da/0x7e0 mm/memory.c:4659
 do_user_addr_fault+0x483/0x1210 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:577
RIP: 0010:__clear_user+0x40/0x70 arch/x86/lib/usercopy_64.c:24
Code: a2 c6 89 e8 f2 ae ba fd 0f 01 cb 48 89 d8 48 c1 eb 03 48 89 ef 83 e0 07 48 89 d9 48 85 c9 74 19 66 2e 0f 1f 84 00 00 00 00 00 <48> c7 07 00 00 00 00 48 83 c7 08 ff c9 75 f1 48 89 c1 85 c9 74 0a
RSP: 0018:ffffc9000908f988 EFLAGS: 00050206
RAX: 0000000000000000 RBX: 0000000000000200 RCX: 000000000000008b
RDX: 0000000000040000 RSI: ffffffff83edb9ae RDI: 00000000206ddfff
RBP: 00000000206dd457 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000004000 R12: 00000000206de457
R13: 00000000206dd457 R14: 0000000000001000 R15: 00000000006dce57
 clear_user+0xd3/0x110 arch/x86/lib/usercopy_64.c:54
 iov_iter_zero+0x242/0x1830 lib/iov_iter.c:1029
 read_iter_zero+0x10f/0x250 drivers/char/mem.c:493
 call_read_iter include/linux/fs.h:2108 [inline]
 do_iter_readv_writev+0x56a/0x740 fs/read_write.c:738
 do_iter_read+0x285/0x6e0 fs/read_write.c:801
 vfs_readv+0xe5/0x150 fs/read_write.c:921
 do_readv+0x139/0x300 fs/read_write.c:958
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff4d104a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000013
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 000000000000000a RSI: 0000000020001900 RDI: 0000000000000006
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007fff582ae9df R14: 00007ff4d104a300 R15: 0000000000022000