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BUG: KMSAN: uninit-value in __call_rcu+0x4b8/0xef0 kernel/rcu/tree.c:3038
CPU: 0 PID: 29 Comm: kworker/u4:2 Not tainted 4.16.0+ #87
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound call_usermodehelper_exec_work
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
 __call_rcu+0x4b8/0xef0 kernel/rcu/tree.c:3038
 call_rcu_sched+0x32/0x40 kernel/rcu/tree.c:3100
 free_pid+0x441/0x450 kernel/pid.c:156
 __change_pid kernel/pid.c:294 [inline]
 detach_pid+0x35a/0x370 kernel/pid.c:299
 __unhash_process kernel/exit.c:75 [inline]
 __exit_signal kernel/exit.c:156 [inline]
 release_task+0x10a0/0x2530 kernel/exit.c:200
 wait_task_zombie kernel/exit.c:1163 [inline]
 wait_consider_task+0x2e29/0x4520 kernel/exit.c:1390
 do_wait_thread kernel/exit.c:1453 [inline]
 do_wait+0x5f8/0xbc0 kernel/exit.c:1524
 kernel_wait4+0x337/0x4b0 kernel/exit.c:1667
 SYSC_wait4+0x111/0x280 kernel/exit.c:1679
 SyS_wait4+0x64/0x90 kernel/exit.c:1675
 call_usermodehelper_exec_sync kernel/umh.c:138 [inline]
 call_usermodehelper_exec_work+0x1e2/0x540 kernel/umh.c:175
 process_one_work+0x12c6/0x1f60 kernel/workqueue.c:2113
 worker_thread+0x113c/0x24f0 kernel/workqueue.c:2247
 kthread+0x539/0x720 kernel/kthread.c:239
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:406

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:293 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:528
 rcu_segcblist_enqueue+0x275/0x2d0 kernel/rcu/rcu_segcblist.c:151
 __call_rcu+0x227/0xef0 kernel/rcu/tree.c:3060
 call_rcu_sched+0x32/0x40 kernel/rcu/tree.c:3100
 file_free fs/file_table.c:55 [inline]
 __fput+0x90e/0xa10 fs/file_table.c:226
 ____fput+0x37/0x40 fs/file_table.c:243
 task_work_run+0x243/0x2c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x10e1/0x38d0 kernel/exit.c:867
 do_group_exit+0x1a0/0x360 kernel/exit.c:970
 SYSC_exit_group+0x21/0x30 kernel/exit.c:981
 SyS_exit_group+0x25/0x30 kernel/exit.c:979
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
Local variable description: ----tlb.i@ldt_arch_exit_mmap
Variable was created at:
 ldt_arch_exit_mmap+0x46/0x160 arch/x86/kernel/ldt.c:298
 arch_exit_mmap arch/x86/include/asm/mmu_context.h:244 [inline]
 exit_mmap+0x30f/0x950 mm/mmap.c:3009
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