syzbot

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BUG: KCSAN: data-race in __dentry_kill / shrink_dentry_list

write to 0xffff88811f1aae40 of 4 bytes by task 18423 on cpu 1:
 d_lru_del fs/dcache.c:410 [inline]
 __dput_to_list fs/dcache.c:891 [inline]
 shrink_dentry_list+0x2e5/0x530 fs/dcache.c:1140
 shrink_dcache_parent+0x4d/0x3f0 fs/dcache.c:1568
 d_invalidate+0x6e/0x1a0 fs/dcache.c:1677
 lookup_fast+0x2ed/0x370 fs/namei.c:1509
 walk_component+0x5c/0x350 fs/namei.c:1856
 link_path_walk+0x462/0x730 fs/namei.c:2179
 path_openat+0x199/0x20a0 fs/namei.c:3364
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811f1aae40 of 4 bytes by task 18424 on cpu 0:
 dentry_unlist fs/dcache.c:544 [inline]
 __dentry_kill+0x1ef/0x450 fs/dcache.c:575
 dentry_kill fs/dcache.c:692 [inline]
 dput+0x208/0x420 fs/dcache.c:878
 handle_mounts fs/namei.c:1389 [inline]
 step_into+0x448/0xe70 fs/namei.c:1690
 walk_component+0x190/0x350 fs/namei.c:1866
 link_path_walk+0x462/0x730 fs/namei.c:2179
 path_openat+0x199/0x20a0 fs/namei.c:3364
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18424 Comm: systemd-udevd Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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