tree 18bef9178b1142d839b906ce3bf38c92eb650ee8
parent 89b0fc38cca4e6c92a90b58960881ffc5dddd89c
author Miklos Szeredi <mszeredi@suse.cz> 1286274669 +0200
committer Al Viro <viro@zeniv.linux.org.uk> 1288056256 -0400

vfs: fix infinite loop caused by clone_mnt race

If clone_mnt() happens while mnt_make_readonly() is running, the
cloned mount might have MNT_WRITE_HOLD flag set, which results in
mnt_want_write() spinning forever on this mount.

Needs CAP_SYS_ADMIN to trigger deliberately and unlikely to happen
accidentally.  But if it does happen it can hang the machine.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>