syzbot

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BUG: KCSAN: data-race in d_set_mounted / dput

write to 0xffff88812b84f000 of 4 bytes by task 11557 on cpu 1:
 d_set_mounted+0x18e/0x1b0 fs/dcache.c:1440
 get_mountpoint+0x135/0x2f0 fs/namespace.c:724
 attach_recursive_mnt+0xae/0x8a0 fs/namespace.c:2056
 graft_tree+0x107/0x160 fs/namespace.c:2179
 do_add_mount.isra.0+0x102/0x190 fs/namespace.c:2725
 do_new_mount_fc fs/namespace.c:2764 [inline]
 do_new_mount fs/namespace.c:2818 [inline]
 do_mount+0x12d5/0x1590 fs/namespace.c:3141
 __do_sys_mount fs/namespace.c:3350 [inline]
 __se_sys_mount fs/namespace.c:3327 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3327
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812b84f000 of 4 bytes by task 11552 on cpu 0:
 fast_dput fs/dcache.c:727 [inline]
 dput+0x4b/0x700 fs/dcache.c:846
 put_fs_context+0x4d/0x350 fs/fs_context.c:470
 do_new_mount fs/namespace.c:2820 [inline]
 do_mount+0x5a3/0x1590 fs/namespace.c:3141
 __do_sys_mount fs/namespace.c:3350 [inline]
 __se_sys_mount fs/namespace.c:3327 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3327
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11552 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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