syzbot

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BUG: KCSAN: data-race in dput / select_collect

write to 0xffff88813401d3c0 of 4 bytes by task 8437 on cpu 0:
 d_lru_del fs/dcache.c:410 [inline]
 select_collect+0xaf/0x2b0 fs/dcache.c:1512
 d_walk+0x298/0x4b0 fs/dcache.c:1333
 shrink_dcache_parent+0x85/0x3f0 fs/dcache.c:1572
 d_invalidate+0x6e/0x1a0 fs/dcache.c:1684
 proc_invalidate_siblings_dcache+0x1e3/0x2d0 fs/proc/inode.c:150
 proc_flush_pid+0x16/0x20 fs/proc/base.c:3326
 release_task+0xa9f/0xb90 kernel/exit.c:222
 wait_task_zombie kernel/exit.c:1107 [inline]
 wait_consider_task+0x104f/0x18e0 kernel/exit.c:1334
 do_wait_thread kernel/exit.c:1397 [inline]
 do_wait+0x1b1/0x4e0 kernel/exit.c:1468
 kernel_wait4+0x13c/0x1a0 kernel/exit.c:1630
 __do_sys_wait4 kernel/exit.c:1658 [inline]
 __se_sys_wait4 kernel/exit.c:1654 [inline]
 __x64_sys_wait4+0x7a/0x100 kernel/exit.c:1654
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88813401d3c0 of 4 bytes by task 26784 on cpu 1:
 fast_dput fs/dcache.c:746 [inline]
 dput+0x2f/0x420 fs/dcache.c:872
 proc_invalidate_siblings_dcache+0x1eb/0x2d0 fs/proc/inode.c:151
 proc_flush_pid+0x16/0x20 fs/proc/base.c:3326
 release_task+0xa9f/0xb90 kernel/exit.c:222
 exit_notify kernel/exit.c:699 [inline]
 do_exit+0xf11/0x1690 kernel/exit.c:845
 do_group_exit+0xce/0x180 kernel/exit.c:922
 get_signal+0xdce/0x14e0 kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a/0x270 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x11a/0x1b0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:294
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26784 Comm: syz-executor.3 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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