syzbot

==================================================================
BUG: KCSAN: data-race in d_shrink_del / dput

write to 0xffff888128e14600 of 4 bytes by task 31910 on cpu 1:
 d_shrink_del+0xcd/0x170 fs/dcache.c:421
 shrink_dentry_list+0x128/0x1d0 fs/dcache.c:1109
 shrink_dcache_sb+0x106/0x1c0 fs/dcache.c:1242
 reconfigure_super+0x318/0x570 fs/super.c:940
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1120/0x14d0 fs/namespace.c:3098
 __do_sys_mount fs/namespace.c:3316 [inline]
 __se_sys_mount fs/namespace.c:3293 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3293
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888128e14600 of 4 bytes by task 32122 on cpu 0:
 fast_dput fs/dcache.c:727 [inline]
 dput+0x4b/0x700 fs/dcache.c:846
 path_put+0x25/0x40 fs/namei.c:482
 free_fs_struct+0x25/0x50 fs/fs_struct.c:91
 exit_fs+0xbd/0xc0 fs/fs_struct.c:108
 do_exit+0x6b3/0x1880 kernel/exit.c:797
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 __do_sys_exit_group kernel/exit.c:910 [inline]
 __se_sys_exit_group kernel/exit.c:908 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:908
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 32122 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================