syzbot

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BUG: KCSAN: data-race in dput / shrink_dentry_list

read-write to 0xffff888107773000 of 4 bytes by task 17443 on cpu 0:
 d_shrink_del fs/dcache.c:421 [inline]
 shrink_dentry_list+0x20f/0x590 fs/dcache.c:1135
 shrink_dcache_sb+0x10d/0x1c0 fs/dcache.c:1268
 reconfigure_super+0x267/0x4d0 fs/super.c:887
 do_remount fs/namespace.c:2618 [inline]
 path_mount+0x13b1/0x1c10 fs/namespace.c:3203
 do_mount fs/namespace.c:3224 [inline]
 __do_sys_mount fs/namespace.c:3432 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3409
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3409
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888107773000 of 4 bytes by task 8453 on cpu 1:
 fast_dput fs/dcache.c:746 [inline]
 dput+0x2f/0x420 fs/dcache.c:872
 path_umount+0xd6/0x9f0 fs/namespace.c:1740
 ksys_umount fs/namespace.c:1760 [inline]
 __do_sys_umount fs/namespace.c:1765 [inline]
 __se_sys_umount fs/namespace.c:1763 [inline]
 __x64_sys_umount+0xa6/0xd0 fs/namespace.c:1763
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8453 Comm: syz-executor.3 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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