fix checks for expand-in-place mremap

#include "internal.h"

#ifndef arch_mmap_check

#define arch_mmap_check(addr, len, flags)	(0)

#endif

static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)

{

	pgd_t *pgd;

static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)

{

	unsigned long end = vma->vm_end + delta;

	unsigned long max_addr = TASK_SIZE;

	if (vma->vm_next)

		max_addr = vma->vm_next->vm_start;

	if (max_addr - vma->vm_end < delta)

	if (max_addr < end || end < vma->vm_end)

		return 0;

	if (arch_mmap_check(vma->vm_start, end - vma->vm_start, MAP_FIXED))

		return 0;

	if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,

			      0, MAP_FIXED) & ~PAGE_MASK)

		return 0;

	/* we need to do arch-specific checks here */

	return 1;

}