Re: [PATCH] Fix do_mlock so page alignment is to hugepage boundries when needed

On Wed, 17 May 2006, Eric Paris wrote:

sys_m{,un}lock and do_mlock all align memory references and the length
of the mlock given by userspace to page boundaries.  If the page being
mlocked is a hugepage instead of a normal page the start and finish of
the mlock will still only be aligned to normal page boundaries.
Ultimately upon the process exiting we will eventually call unmap_vmas
which will call unmap_hugepage_range for all of the ranges.
unmap_hugepage_range checks to make sure the beginning and the end of
the range are actually hugepage aligned and if not will BUG().  Since we
only aligned to a normal page boundary the end of the first range and
the beginning of the second will likely (unless userspace passed of
values already hugepage aligned) not be hugepage aligned and thus we
bomb.

When did you test this?  It should have been fixed in 2.6.11 onwards
by split_vma()'s simple:

	if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
		return -EINVAL;

Hugh