syzbot

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BUG: KCSAN: data-race in d_lru_del / lookup_fast

write to 0xffff888124d11240 of 4 bytes by task 1 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+0x83/0xc60 kernel/exit.c:202
 wait_task_zombie kernel/exit.c:1106 [inline]
 wait_consider_task+0x190e/0x1a10 kernel/exit.c:1333
 do_wait_thread kernel/exit.c:1396 [inline]
 do_wait+0x1c9/0x4c0 kernel/exit.c:1467
 kernel_wait4+0x156/0x240 kernel/exit.c:1639
 __do_sys_wait4+0xea/0x100 kernel/exit.c:1651
 __se_sys_wait4 kernel/exit.c:1647 [inline]
 __x64_sys_wait4+0x5e/0x80 kernel/exit.c:1647
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888124d11240 of 4 bytes by task 8184 on cpu 1:
 lookup_fast+0x59e/0x700 fs/namei.c:1614
 walk_component+0x6d/0xe70 fs/namei.c:1796
 link_path_walk.part.0+0x5d3/0xa90 fs/namei.c:2131
 link_path_walk fs/namei.c:2062 [inline]
 path_openat+0x14f/0x36e0 fs/namei.c:3524
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8184 Comm: ps Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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