From: Trond Myklebust Ensure that the dummy 'root dentry' is invisible to d_find_alias(). If not, then it may be spliced into the tree if a parent directory from the same filesystem gets mounted at a later time. Signed-off-by: Trond Myklebust Signed-off-by: Andrew Morton --- fs/nfs/getroot.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff -puN fs/nfs/getroot.c~nfs-fix-an-oops-in-nfs-unmount fs/nfs/getroot.c --- a/fs/nfs/getroot.c~nfs-fix-an-oops-in-nfs-unmount +++ a/fs/nfs/getroot.c @@ -57,6 +57,17 @@ static int nfs_superblock_set_dummy_root } /* Circumvent igrab(): we know the inode is not being freed */ atomic_inc(&inode->i_count); + /* + * Ensure that this dentry is invisible to d_find_alias(). + * Otherwise, it may be spliced into the tree by + * d_materialise_unique if a parent directory from the same + * filesystem gets mounted at a later time. + * This again causes shrink_dcache_for_umount_subtree() to + * Oops, since the test for IS_ROOT() will fail. + */ + spin_lock(&dcache_lock); + list_del_init(&sb->s_root->d_alias); + spin_unlock(&dcache_lock); } return 0; } _