syzbot

==================================================================
BUG: KCSAN: data-race in dentry_lru_isolate_shrink / lookup_fast

write to 0xffff8881013bab40 of 4 bytes by task 3959 on cpu 1:
 d_lru_shrink_move fs/dcache.c:455 [inline]
 dentry_lru_isolate_shrink+0x7b/0x100 fs/dcache.c:1275
 __list_lru_walk_one+0xfb/0x320 mm/list_lru.c:231
 list_lru_walk_node+0x116/0x1a0 mm/list_lru.c:311
 list_lru_walk include/linux/list_lru.h:215 [inline]
 shrink_dcache_sb+0xc8/0x2d0 fs/dcache.c:1294
 reconfigure_super+0x146/0x540 fs/super.c:891
 do_remount fs/namespace.c:2650 [inline]
 path_mount+0x13f9/0x1c40 fs/namespace.c:3310
 do_mount fs/namespace.c:3331 [inline]
 __do_sys_mount fs/namespace.c:3539 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3516
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3516
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881013bab40 of 4 bytes by task 1815 on cpu 0:
 d_revalidate fs/namei.c:853 [inline]
 lookup_fast+0x172/0x360 fs/namei.c:1606
 walk_component+0x6d/0x360 fs/namei.c:1966
 lookup_last fs/namei.c:2425 [inline]
 path_lookupat+0x12d/0x3d0 fs/namei.c:2449
 filename_lookup+0x130/0x310 fs/namei.c:2478
 user_path_at_empty+0x3e/0x110 fs/namei.c:2801
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1773 [inline]
 __do_sys_umount fs/namespace.c:1781 [inline]
 __se_sys_umount fs/namespace.c:1779 [inline]
 __x64_sys_umount+0x84/0xe0 fs/namespace.c:1779
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00280040 -> 0x00008040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1815 Comm: syz-executor.0 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================