syzbot

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BUG: KCSAN: data-race in dont_mount / step_into

read-write to 0xffff8881096aecc0 of 4 bytes by task 3869 on cpu 0:
 dont_mount+0x27/0x40 include/linux/dcache.h:351
 vfs_unlink+0x282/0x3e0 fs/namei.c:4329
 do_unlinkat+0x26c/0x4f0 fs/namei.c:4393
 __do_sys_unlink fs/namei.c:4441 [inline]
 __se_sys_unlink fs/namei.c:4439 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4439
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881096aecc0 of 4 bytes by task 2745 on cpu 1:
 __follow_mount_rcu fs/namei.c:1483 [inline]
 handle_mounts fs/namei.c:1534 [inline]
 step_into+0xe7/0x800 fs/namei.c:1836
 walk_component+0x164/0x230 fs/namei.c:2004
 lookup_last fs/namei.c:2455 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2479
 filename_lookup+0x126/0x300 fs/namei.c:2508
 user_path_at_empty+0x42/0x110 fs/namei.c:2907
 do_readlinkat+0x92/0x210 fs/stat.c:477
 __do_sys_readlink fs/stat.c:510 [inline]
 __se_sys_readlink fs/stat.c:507 [inline]
 __x64_sys_readlink+0x47/0x50 fs/stat.c:507
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00600008 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2745 Comm: udevd Not tainted 6.4.0-rc5-syzkaller-00017-ga27648c74210 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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