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BUG: KCSAN: data-race in __mnt_want_write / propagate_one

write to 0xffff8880acdbea30 of 4 bytes by task 4841 on cpu 0:
 propagate_one fs/pnode.c:269 [inline]
 propagate_one+0x3b3/0x550 fs/pnode.c:225
 propagate_mnt+0x22e/0x270 fs/pnode.c:320
 attach_recursive_mnt+0x66d/0x8a0 fs/namespace.c:2071
 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 0xffff8880acdbea30 of 4 bytes by task 4838 on cpu 1:
 __mnt_is_readonly fs/namespace.c:248 [inline]
 mnt_is_readonly fs/namespace.c:292 [inline]
 __mnt_want_write+0xdf/0x1b0 fs/namespace.c:332
 mnt_want_write+0x3d/0x80 fs/namespace.c:355
 filename_create+0xb8/0x2d0 fs/namei.c:3439
 user_path_create fs/namei.c:3502 [inline]
 do_symlinkat+0x90/0x1e0 fs/namei.c:3957
 __do_sys_symlink fs/namei.c:3983 [inline]
 __se_sys_symlink fs/namei.c:3981 [inline]
 __x64_sys_symlink+0x3c/0x50 fs/namei.c:3981
 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: 1 PID: 4838 Comm: syz-executor.3 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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