syzbot

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BUG: KCSAN: data-race in __dentry_kill / d_lru_del

read to 0xffff88812247a180 of 4 bytes by task 8976 on cpu 1:
 dentry_unlist fs/dcache.c:544 [inline]
 __dentry_kill+0x1be/0x3c0 fs/dcache.c:575
 dentry_kill fs/dcache.c:698 [inline]
 dput+0x3b5/0x750 fs/dcache.c:859
 proc_flush_task_mnt fs/proc/base.c:3148 [inline]
 proc_flush_task+0x155/0x2e0 fs/proc/base.c:3217
 release_task+0x83/0xc70 kernel/exit.c:202
 exit_notify kernel/exit.c:687 [inline]
 do_exit+0xdae/0x18f0 kernel/exit.c:838
 do_group_exit+0xb4/0x1c0 kernel/exit.c:921
 get_signal+0x2a2/0x1320 kernel/signal.c:2734
 do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812247a180 of 4 bytes by task 8938 on cpu 0:
 d_lru_del+0x5d/0xf0 fs/dcache.c:410
 __dput_to_list+0xe9/0xf0 fs/dcache.c:872
 shrink_dentry_list+0x101/0x1c0 fs/dcache.c:1119
 shrink_dcache_parent+0x1ef/0x280 fs/dcache.c:1547
 d_invalidate fs/dcache.c:1656 [inline]
 d_invalidate+0x85/0x180 fs/dcache.c:1641
 proc_flush_task_mnt fs/proc/base.c:3147 [inline]
 proc_flush_task+0x14c/0x2e0 fs/proc/base.c:3217
 release_task+0x83/0xc70 kernel/exit.c:202
 exit_notify kernel/exit.c:687 [inline]
 do_exit+0xdae/0x18f0 kernel/exit.c:838
 do_group_exit+0xb4/0x1c0 kernel/exit.c:921
 get_signal+0x2a2/0x1320 kernel/signal.c:2734
 do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8938 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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