syzbot

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BUG: KMSAN: uninit-value in rcu_segcblist_pend_cbs+0xa9/0xf0 kernel/rcu/rcu_segcblist.c:104
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.17.0+ #9
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
 __msan_warning_32+0x70/0xc0 mm/kmsan/kmsan_instr.c:620
 rcu_segcblist_pend_cbs+0xa9/0xf0 kernel/rcu/rcu_segcblist.c:104
 rcu_accelerate_cbs+0x7e/0xca0 kernel/rcu/tree.c:1810
 rcu_report_qs_rdp kernel/rcu/tree.c:2514 [inline]
 rcu_check_quiescent_state kernel/rcu/tree.c:2553 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2881 [inline]
 rcu_process_callbacks+0x84b/0x2060 kernel/rcu/tree.c:2914
 __do_softirq+0x592/0x979 kernel/softirq.c:285
 invoke_softirq kernel/softirq.c:365 [inline]
 irq_exit+0x202/0x240 kernel/softirq.c:405
 exiting_irq+0xe/0x10 arch/x86/include/asm/apic.h:525
 smp_apic_timer_interrupt+0x64/0x90 arch/x86/kernel/apic/apic.c:1055
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:866
 </IRQ>
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:55 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:97 [inline]
RIP: 0010:default_idle+0x20b/0x3e0 arch/x86/kernel/process.c:500
RSP: 0018:ffff8801d8e5fdf0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8801fd432f18 RBX: 0000000000000000 RCX: ffff880000000000
RDX: ffff8801fd032f18 RSI: aaaaaaaaaaaab000 RDI: ffffea0000000000
RBP: ffff8801d8e5fe28 R08: 0000000001080020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff89fef830 R12: ffff8801d8e5fe8f
R13: ffff8801d8da57c0 R14: ffff8801d8e5fe8c R15: ffff8801d8da6098
 arch_cpu_idle+0x26/0x30 arch/x86/kernel/process.c:491
 default_idle_call kernel/sched/idle.c:93 [inline]
 cpuidle_idle_call kernel/sched/idle.c:153 [inline]
 do_idle+0x36d/0x830 kernel/sched/idle.c:262
 cpu_startup_entry+0x45/0x50 kernel/sched/idle.c:368
 start_secondary+0x3c6/0x490 arch/x86/kernel/smpboot.c:272
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:297 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:689
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:464
 rcu_segcblist_enqueue+0x275/0x2d0 kernel/rcu/rcu_segcblist.c:151
 __call_rcu+0x227/0xef0 kernel/rcu/tree.c:3057
 call_rcu_sched+0x32/0x40 kernel/rcu/tree.c:3097
 release_task+0x24b9/0x2530 kernel/exit.c:223
 exit_notify kernel/exit.c:736 [inline]
 do_exit+0x2e11/0x3930 kernel/exit.c:887
 do_group_exit+0x1a0/0x360 kernel/exit.c:970
 get_signal+0x1405/0x1ec0 kernel/signal.c:2482
 do_signal+0xb8/0x1d20 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:162 [inline]
 prepare_exit_to_usermode+0x271/0x3a0 arch/x86/entry/common.c:196
 syscall_return_slowpath+0xe9/0x710 arch/x86/entry/common.c:265
 do_syscall_64+0x1ad/0x230 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Local variable description: ----tlb@exit_mmap
Variable was created at:
 exit_mmap+0x47/0x980 mm/mmap.c:3051
 __mmput+0x158/0x600 kernel/fork.c:962
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