syzbot

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BUG: KCSAN: data-race in __lookup_mnt / umount_tree

write to 0xffff888135a3e510 of 8 bytes by task 3129 on cpu 0:
 unhash_mnt fs/namespace.c:905 [inline]
 umount_mnt fs/namespace.c:920 [inline]
 umount_tree+0x574/0x860 fs/namespace.c:1675
 path_umount+0x928/0x9a0 fs/namespace.c:1896
 ksys_umount fs/namespace.c:1919 [inline]
 __do_sys_umount fs/namespace.c:1924 [inline]
 __se_sys_umount fs/namespace.c:1922 [inline]
 __x64_sys_umount+0xb9/0xe0 fs/namespace.c:1922
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888135a3e510 of 8 bytes by task 15045 on cpu 1:
 __lookup_mnt+0x83/0xf0 fs/namespace.c:696
 __follow_mount_rcu fs/namei.c:1508 [inline]
 handle_mounts fs/namei.c:1538 [inline]
 step_into+0x430/0x800 fs/namei.c:1840
 walk_component fs/namei.c:2008 [inline]
 link_path_walk+0x4d8/0x7e0 fs/namei.c:2329
 path_parentat fs/namei.c:2530 [inline]
 __filename_parentat+0x13b/0x3c0 fs/namei.c:2554
 filename_parentat fs/namei.c:2572 [inline]
 do_renameat2+0x32e/0xa40 fs/namei.c:4912
 __do_sys_rename fs/namei.c:5042 [inline]
 __se_sys_rename fs/namei.c:5040 [inline]
 __x64_sys_rename+0x5c/0x70 fs/namei.c:5040
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0xffff8881330dcc80 -> 0xffff888135a3e500

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15045 Comm: udevd Not tainted 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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