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

write to 0xffff888102e98600 of 4 bytes by task 18674 on cpu 1:
 shrink_dentry_list+0x127/0x580 fs/dcache.c:421
 shrink_dcache_sb+0x10d/0x1c0 fs/dcache.c:1294
 reconfigure_super+0x2aa/0x4f0 fs/super.c:888
 do_remount fs/namespace.c:2637 [inline]
 path_mount+0x1444/0x1ce0 fs/namespace.c:3225
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888102e98600 of 4 bytes by task 18670 on cpu 0:
 link_path_walk+0x37d/0x780 fs/namei.c:2232
 path_parentat fs/namei.c:2474 [inline]
 filename_parentat+0x104/0x950 fs/namei.c:2496
 filename_create+0x58/0x3c0 fs/namei.c:3581
 user_path_create fs/namei.c:3656 [inline]
 do_mkdirat+0x59/0x200 fs/namei.c:3834
 __do_sys_mkdir fs/namei.c:3862 [inline]
 __se_sys_mkdir fs/namei.c:3860 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3860
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18670 Comm: syz-executor.1 Tainted: G        W         5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================