syzbot

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BUG: KMSAN: uninit-value in rcu_segcblist_ready_cbs+0xab/0xe0 kernel/rcu/rcu_segcblist.c:94
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.17.0+ #17
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:1368
 __msan_warning_32+0x70/0xc0 mm/kmsan/kmsan_instr.c:634
 rcu_segcblist_ready_cbs+0xab/0xe0 kernel/rcu/rcu_segcblist.c:94
 __rcu_pending kernel/rcu/tree.c:3367 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x13c3/0x2ae0 kernel/rcu/tree.c:2763
 update_process_times+0x132/0x1a0 kernel/time/timer.c:1636
 tick_sched_handle kernel/time/tick-sched.c:164 [inline]
 tick_sched_timer+0x3ba/0x520 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0xc54/0x1630 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x451/0x13c0 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt+0x6b/0x250 arch/x86/kernel/apic/apic.c:1025
 smp_apic_timer_interrupt+0x5a/0x90 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:868
 </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:ffffffff8ac0fd90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8801fd432f18 RBX: 0000000000000000 RCX: ffff8801fd032f18
RDX: ffff8801fd032f18 RSI: aaaaaaaaaaaab000 RDI: ffffea00004212c0
RBP: ffffffff8ac0fdc8 R08: 0000000001080020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff89ff18c0 R12: ffffffff8ac0fe2f
R13: ffffffff8ac372c0 R14: ffffffff8ac0fe2c R15: ffffffff8ac37b98
 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
 rest_init+0x1c1/0x1f0 init/main.c:443
 start_kernel+0x1110/0x1120 init/main.c:740
 x86_64_start_reservations arch/x86/kernel/head64.c:453 [inline]
 x86_64_start_kernel+0xf0/0x100 arch/x86/kernel/head64.c:434
 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:287 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:302 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:692
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:478
 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+0x63/0xe7

Local variable description: ----tlb.i@ldt_arch_exit_mmap
Variable was created at:
 ldt_arch_exit_mmap+0x46/0x160 arch/x86/kernel/ldt.c:302
 arch_exit_mmap arch/x86/include/asm/mmu_context.h:245 [inline]
 exit_mmap+0x410/0x980 mm/mmap.c:3094
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