INFO: rcu detected stall in bsearch

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 11da3a7f84f1 Linux 4.19-rc3
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13dd3cda400000
kernel config: https://syzkaller.appspot.com/x/.config?x=9917ff4b798e1a1e
dashboard link: https://syzkaller.appspot.com/bug?extid=863146b3ebbde69454d3
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [jpoi...@redhat.com linux-...@vger.kernel.org
mhir...@kernel.org mi...@kernel.org pau...@linux.vnet.ibm.com
pet...@infradead.org ros...@goodmis.org zhouche...@huawei.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+863146...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (10500 ticks this GP) idle=4e2/1/0x4000000000000002
softirq=38153/38153 fqs=0
rcu: (t=10502 jiffies g=55257 q=30)
rcu: rcu_preempt kthread starved for 10503 jiffies! g55257 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt R running task 22872 10 2 0x80000000
Call Trace:
context_switch kernel/sched/core.c:2825 [inline]
__schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
schedule+0xfe/0x460 kernel/sched/core.c:3517
schedule_timeout+0x140/0x260 kernel/time/timer.c:1804
rcu_gp_kthread+0x9d9/0x2310 kernel/rcu/tree.c:2194
kthread+0x35a/0x420 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
NMI backtrace for cpu 0
CPU: 0 PID: 20782 Comm: syz-executor3 Not tainted 4.19.0-rc3+ #231
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_single_cpu_backtrace include/linux/nmi.h:162 [inline]
rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340
print_cpu_stall.cold.78+0x2d3/0x524 kernel/rcu/tree.c:1478
check_cpu_stall kernel/rcu/tree.c:1550 [inline]
__rcu_pending kernel/rcu/tree.c:3276 [inline]
rcu_pending kernel/rcu/tree.c:3319 [inline]
rcu_check_callbacks+0xfd9/0x1990 kernel/rcu/tree.c:2665
update_process_times+0x2d/0x70 kernel/time/timer.c:1636
tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
__run_hrtimer kernel/time/hrtimer.c:1398 [inline]
__hrtimer_run_queues+0x41c/0x10d0 kernel/time/hrtimer.c:1460
hrtimer_interrupt+0x313/0x780 kernel/time/hrtimer.c:1518
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1029 [inline]
smp_apic_timer_interrupt+0x1a1/0x760 arch/x86/kernel/apic/apic.c:1054
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
</IRQ>
RIP: 0010:ex_to_insn lib/extable.c:23 [inline]
RIP: 0010:cmp_ex_search+0x44/0xb0 lib/extable.c:104
Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 75 48 89 da 4d 8b 24
24 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 0f b6 14 02 <48> 89 d8 83 e0
07 83 c0 03 38 d0 7c 04 84 d2 75 41 48 63 33 4c 89
RSP: 0018:ffff880184136748 EFLAGS: 00000a03 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffffffff87e08374 RCX: ffffc9000ead6000
RDX: 0000000000000000 RSI: ffffffff87b81844 RDI: ffff8801841367e0
RBP: ffff880184136760 R08: ffff8801b75ae000 R09: ffff880184136930
R10: ffffed0030826d35 R11: ffff8801841369af R12: ffffffff81147628
R13: ffffffff87e08374 R14: 000000000000014f R15: 000000000000000c
bsearch+0x5d/0xc0 lib/bsearch.c:41
search_extable+0x80/0xb0 lib/extable.c:123
search_exception_tables+0x37/0x50 kernel/extable.c:60
fixup_exception+0x44/0xcb arch/x86/mm/extable.c:192
do_trap_no_signal arch/x86/kernel/traps.c:209 [inline]
do_trap+0x63/0x240 arch/x86/kernel/traps.c:258
do_error_trap+0x185/0x4d0 arch/x86/kernel/traps.c:303
do_divide_error+0x18/0x20 arch/x86/kernel/traps.c:314
divide_error+0x14/0x20 arch/x86/entry/entry_64.S:990
RIP: 0010:em_idiv_ex+0x0/0x8
Code: 00 00 48 f7 e9 c3 0f 1f 40 00 f6 f1 c3 0f 1f 44 00 00 66 f7 f1 c3 0f
1f 40 00 f7 f1 c3 0f 1f 44 00 00 48 f7 f1 c3 0f 1f 40 00 <f6> f9 c3 0f 1f
44 00 00 66 f7 f9 c3 0f 1f 40 00 f7 f9 c3 0f 1f 44
RSP: 0018:ffff880184136ae0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff88019daebe60 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81147628 RDI: 0000000000000200
RBP: ffff880184136b18 R08: ffff8801b75ae000 R09: 1ffffffff12b43d5
R10: ffffed003b5c4732 R11: ffff8801dae23993 R12: 0000000000000000
R13: ffffffff81147628 R14: 0000000000000001 R15: ffffffff81147628
x86_emulate_insn+0x1efd/0x5020 arch/x86/kvm/emulate.c:5587
x86_emulate_instruction+0xd45/0x1fc0 arch/x86/kvm/x86.c:6224
kvm_mmu_page_fault+0x396/0x1b30 arch/x86/kvm/mmu.c:5280
handle_ept_violation+0x29e/0x6a0 arch/x86/kvm/vmx.c:7679
vmx_handle_exit+0x2f7/0x17e0 arch/x86/kvm/vmx.c:10115
vcpu_enter_guest+0x14a9/0x62e0 arch/x86/kvm/x86.c:7648
vcpu_run arch/x86/kvm/x86.c:7711 [inline]
kvm_arch_vcpu_ioctl_run+0x375/0x16e0 arch/x86/kvm/x86.c:7888
kvm_vcpu_ioctl+0x72b/0x1150 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
__do_sys_ioctl fs/ioctl.c:709 [inline]
__se_sys_ioctl fs/ioctl.c:707 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457099
Code: fd b4 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd04dcbac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd04dcbb6d4 RCX: 0000000000457099
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cf730 R14: 00000000004c59b9 R15: 0000000000000000


---
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[Dmitry Vyukov]

#syz dup: INFO: rcu detected stall in kvm_vcpu_ioctl

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