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BUG: KCSAN: data-race in __d_lookup_done / __dentry_kill

write to 0xffff888121333a80 of 4 bytes by task 21894 on cpu 0:
 __d_lookup_done+0xa4/0x2f0 fs/dcache.c:2629
 d_lookup_done include/linux/dcache.h:367 [inline]
 d_lookup_done include/linux/dcache.h:363 [inline]
 __lookup_slow+0x22b/0x270 fs/namei.c:1531
 lookup_slow fs/namei.c:1547 [inline]
 walk_component+0x296/0x390 fs/namei.c:1846
 link_path_walk.part.0+0x469/0x700 fs/namei.c:2169
 link_path_walk fs/namei.c:2098 [inline]
 path_openat+0x191/0x23d0 fs/namei.c:3342
 do_filp_open+0x11e/0x1b0 fs/namei.c:3373
 do_sys_openat2+0x52e/0x680 fs/open.c:1148
 do_sys_open+0xa2/0x110 fs/open.c:1164
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x50/0x60 fs/open.c:1168
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888121333a80 of 4 bytes by task 19468 on cpu 1:
 dentry_unlist fs/dcache.c:544 [inline]
 __dentry_kill+0x1b4/0x3b0 fs/dcache.c:575
 dentry_kill fs/dcache.c:698 [inline]
 dput+0x399/0x700 fs/dcache.c:859
 handle_mounts fs/namei.c:1375 [inline]
 step_into+0x8a3/0x1090 fs/namei.c:1676
 walk_component+0xde/0x390 fs/namei.c:1852
 link_path_walk.part.0+0x469/0x700 fs/namei.c:2169
 link_path_walk fs/namei.c:2098 [inline]
 path_openat+0x191/0x23d0 fs/namei.c:3342
 do_filp_open+0x11e/0x1b0 fs/namei.c:3373
 do_sys_openat2+0x52e/0x680 fs/open.c:1148
 do_sys_open+0xa2/0x110 fs/open.c:1164
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x50/0x60 fs/open.c:1168
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19468 Comm: systemd-udevd Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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