syzbot

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BUG: KCSAN: data-race in dput / vfs_unlink

write to 0xffff888144936240 of 4 bytes by task 15901 on cpu 0:
 dont_mount include/linux/dcache.h:357 [inline]
 vfs_unlink+0x289/0x3e0 fs/namei.c:4033
 do_unlinkat+0x29f/0x4f0 fs/namei.c:4098
 __do_sys_unlink fs/namei.c:4145 [inline]
 __se_sys_unlink fs/namei.c:4143 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:4143
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888144936240 of 4 bytes by task 4830 on cpu 1:
 fast_dput fs/dcache.c:747 [inline]
 dput+0x34/0x430 fs/dcache.c:873
 path_put+0x1b/0x30 fs/namei.c:546
 do_readlinkat+0x188/0x200 fs/stat.c:432
 __do_sys_readlink fs/stat.c:450 [inline]
 __se_sys_readlink fs/stat.c:447 [inline]
 __x64_sys_readlink+0x43/0x50 fs/stat.c:447
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4830 Comm: systemd-udevd 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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