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BUG: KCSAN: data-race in __dentry_kill / lookup_fast

write to 0xffff888105e5c3c0 of 4 bytes by task 19550 on cpu 0:
 dentry_unlist fs/dcache.c:520 [inline]
 __dentry_kill+0x147/0x4e0 fs/dcache.c:576
 dentry_kill fs/dcache.c:693 [inline]
 dput+0xc6/0x360 fs/dcache.c:886
 handle_mounts fs/namei.c:1475 [inline]
 step_into+0x442/0xec0 fs/namei.c:1773
 walk_component+0x190/0x350 fs/namei.c:1949
 lookup_last fs/namei.c:2398 [inline]
 path_lookupat+0x12d/0x570 fs/namei.c:2422
 filename_lookup+0xff/0x390 fs/namei.c:2455
 user_path_at_empty+0x3b/0x50 fs/namei.c:2735
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x98/0x290 fs/stat.c:195
 vfs_fstatat fs/stat.c:217 [inline]
 vfs_stat include/linux/fs.h:3236 [inline]
 __do_sys_newstat fs/stat.c:359 [inline]
 __se_sys_newstat+0x46/0x250 fs/stat.c:355
 __x64_sys_newstat+0x2d/0x40 fs/stat.c:355
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105e5c3c0 of 4 bytes by task 19548 on cpu 1:
 d_revalidate fs/namei.c:826 [inline]
 lookup_fast+0x15f/0x350 fs/namei.c:1579
 walk_component+0x5c/0x350 fs/namei.c:1939
 lookup_last fs/namei.c:2398 [inline]
 path_lookupat+0x12d/0x570 fs/namei.c:2422
 filename_lookup+0xff/0x390 fs/namei.c:2455
 user_path_at_empty+0x3b/0x50 fs/namei.c:2735
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x98/0x290 fs/stat.c:195
 vfs_fstatat fs/stat.c:217 [inline]
 vfs_stat include/linux/fs.h:3236 [inline]
 __do_sys_newstat fs/stat.c:359 [inline]
 __se_sys_newstat+0x46/0x250 fs/stat.c:355
 __x64_sys_newstat+0x2d/0x40 fs/stat.c:355
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19548 Comm: modprobe Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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