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1
WARNING: kernel/rcu/tree_stall.h:1049 at rcu_check_gp_start_stall.part.0+0x1c4/0x4b0 kernel/rcu/tree_stall.h:1049, CPU#1: syz.4.1521/11587
Modules linked in:
CPU: 1 UID: 0 PID: 11587 Comm: syz.4.1521 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:rcu_check_gp_start_stall.part.0+0x1c4/0x4b0 kernel/rcu/tree_stall.h:1049
Code: 88 61 01 00 00 be 04 00 00 00 48 c7 c7 40 d3 18 9b e8 00 32 88 00 b8 01 00 00 00 87 05 55 16 2c 19 85 c0 0f 85 3d 01 00 00 90 <0f> 0b 90 48 c7 c3 c4 61 d7 90 48 81 fd 00 08 7f 8e 74 5a 48 b8 00
RSP: 0018:ffffc90000590de8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000002904 RCX: ffffffff81ecbce0
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff9b18d340
RBP: ffffffff8e7f0800 R08: 0000000000000001 R09: fffffbfff3631a68
R10: 0000000000000003 R11: 0000000000000000 R12: 1ffffffff1c81e50
R13: 0000000000000246 R14: 0000000000000080 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88809728d000(0063) knlGS:0000000056f1d480
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000034a1aff8 CR3: 0000000066fee000 CR4: 0000000000352ef0
Call Trace:
 <IRQ>
 rcu_check_gp_start_stall kernel/rcu/tree_stall.h:1012 [inline]
 rcu_core+0x2cb/0x10d0 kernel/rcu/tree.c:2864
 handle_softirqs+0x1ea/0xa00 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline]
RIP: 0010:write_comp_data+0x3a/0x90 kernel/kcov.c:246
Code: 65 48 8b 3d 10 3a 01 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 e9 c0 b6 81 09 8b 87 ec 16 00 00 85 c0 74 f1 <8b> 87 c8 16 00 00 83 f8 03 75 e6 48 8b 87 d0 16 00 00 8b bf cc 16
RSP: 0018:ffffc9000666f4d0 EFLAGS: 00000246
RAX: 0000000000000003 RBX: 0000000000000003 RCX: ffffffff81fb825d
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888022304a80
RBP: ffff88802b543060 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10056a860d R14: 0000000000000001 R15: ffff88802b33c740
 csd_lock_wait kernel/smp.c:342 [inline]
 smp_call_function_many_cond+0x5ad/0x1700 kernel/smp.c:892
 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057
 kvm_flush_tlb_multi+0x22e/0x370 arch/x86/kernel/kvm.c:687
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451
 flush_tlb_batched_pending+0x93/0xe0 mm/rmap.c:817
 change_pte_range mm/mprotect.c:339 [inline]
 change_pmd_range mm/mprotect.c:537 [inline]
 change_pud_range mm/mprotect.c:600 [inline]
 change_p4d_range mm/mprotect.c:626 [inline]
 change_protection_range mm/mprotect.c:654 [inline]
 change_protection+0x1326/0x52f0 mm/mprotect.c:688
 mprotect_fixup+0x439/0xe30 mm/mprotect.c:807
 do_mprotect_pkey+0xa4b/0xef0 mm/mprotect.c:967
 __do_sys_mprotect mm/mprotect.c:988 [inline]
 __se_sys_mprotect mm/mprotect.c:985 [inline]
 __ia32_sys_mprotect+0x75/0xb0 mm/mprotect.c:985
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe7/0x970 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf70aef7c
Code: d2 74 05 c1 e8 0c 89 02 8b 5d fc 31 c0 c9 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 58 b8
RSP: 002b:00000000ffe56678 EFLAGS: 00000286 ORIG_RAX: 000000000000007d
RAX: ffffffffffffffda RBX: 00000000f545d000 RCX: 0000000000020000
RDX: 0000000000000003 RSI: 0000000000001000 RDI: 0000000000021000
RBP: 00000000f547cb40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	65 48 8b 3d 10 3a 01 	mov    %gs:0x12013a10(%rip),%rdi        # 0x12013a18
   7:	12
   8:	a9 00 01 ff 00       	test   $0xff0100,%eax
   d:	74 1b                	je     0x2a
   f:	f6 c4 01             	test   $0x1,%ah
  12:	74 07                	je     0x1b
  14:	a9 00 00 ff 00       	test   $0xff0000,%eax
  19:	74 05                	je     0x20
  1b:	e9 c0 b6 81 09       	jmp    0x981b6e0
  20:	8b 87 ec 16 00 00    	mov    0x16ec(%rdi),%eax
  26:	85 c0                	test   %eax,%eax
  28:	74 f1                	je     0x1b
* 2a:	8b 87 c8 16 00 00    	mov    0x16c8(%rdi),%eax <-- trapping instruction
  30:	83 f8 03             	cmp    $0x3,%eax
  33:	75 e6                	jne    0x1b
  35:	48 8b 87 d0 16 00 00 	mov    0x16d0(%rdi),%rax
  3c:	8b                   	.byte 0x8b
  3d:	bf                   	.byte 0xbf
  3e:	cc                   	int3
  3f:	16                   	(bad)