Re: [PATCH] regression: vmalloc easily fail.

[Roland Dreier <rdreier@cisco.com>]

 > I'm guessing that the missing comment explains that this is
 > intentional, to trap buffer overflows?

Actually, speaking of comments, it's interesting that
__get_vm_area_node() -- which is called from vmalloc() -- does:

	/*
	 * We always allocate a guard page.
	 */
	size += PAGE_SIZE;

	va = alloc_vmap_area(size, align, start, end, node, gfp_mask);

and alloc_vmap_area() adds another PAGE_SIZE, as the original email
pointed out:

		while (addr + size >= first->va_start && addr + size <= vend) {
			addr = ALIGN(first->va_end + PAGE_SIZE, align);

I wonder if the double padding is causing a problem when things get too
fragmented?

 - R.