==================================================================
BUG: KCSAN: data-race in link_path_walk / shrink_dentry_list

write to 0xffff8881329bda80 of 4 bytes by task 23112 on cpu 1:
 shrink_dentry_list+0x127/0x540 fs/dcache.c:423
 shrink_dcache_sb+0x188/0x2d0 fs/dcache.c:1296
 reconfigure_super+0x146/0x540 fs/super.c:891
 do_remount fs/namespace.c:2656 [inline]
 path_mount+0x13f9/0x1c40 fs/namespace.c:3316
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3522
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3522
 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 0xffff8881329bda80 of 4 bytes by task 1838 on cpu 0:
 __d_entry_type include/linux/dcache.h:395 [inline]
 d_can_lookup include/linux/dcache.h:410 [inline]
 link_path_walk+0x54c/0x990 fs/namei.c:2307
 path_lookupat+0x8b/0x3d0 fs/namei.c:2448
 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:1779 [inline]
 __do_sys_umount fs/namespace.c:1787 [inline]
 __se_sys_umount fs/namespace.c:1785 [inline]
 __x64_sys_umount+0x84/0xe0 fs/namespace.c:1785
 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: 0x00280400 -> 0x00200000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1838 Comm: syz-executor.5 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================