参照元

説明

引数

返り値

参考

実装

/*
 * mlock_fixup  - handle mlock[all]/munlock[all] requests.
 *
 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
 * munlock is a no-op.  However, for some special vmas, we go ahead and
 * populate the ptes via make_pages_present().
 *
 * For vmas that pass the filters, merge/split as appropriate.
 */
static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
	unsigned long start, unsigned long end, unsigned int newflags)
{
	struct mm_struct *mm = vma->vm_mm;
	pgoff_t pgoff;
	int nr_pages;
	int ret = 0;
	int lock = newflags & VM_LOCKED;
	if (newflags == vma->vm_flags ||
			(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;	/* don't set VM_LOCKED,  don't count */
	if ((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
			is_vm_hugetlb_page(vma) ||
			vma == get_gate_vma(current)) {
		if (lock)
			make_pages_present(start, end);
		goto out;	/* don't set VM_LOCKED,  don't count */
	}
	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
			  vma->vm_file, pgoff, vma_policy(vma));
	if (*prev) {
		vma = *prev;
		goto success;
	}
	if (start != vma->vm_start) {
		ret = split_vma(mm, vma, start, 1);
		if (ret)
			goto out;
	}
	if (end != vma->vm_end) {
		ret = split_vma(mm, vma, end, 0);
		if (ret)
			goto out;
	}

success:
	/*
	 * Keep track of amount of locked VM.
	 */
	nr_pages = (end - start) >> PAGE_SHIFT;
	if (!lock)
		nr_pages = -nr_pages;
	mm->locked_vm += nr_pages;

	/*
	 * vm_flags is protected by the mmap_sem held in write mode.
	 * It's okay if try_to_unmap_one unmaps a page just after we
	 * set VM_LOCKED, __mlock_vma_pages_range will bring it back.
	 */

	if (lock) {
		vma->vm_flags = newflags;
		ret = __mlock_vma_pages_range(vma, start, end);
		if (ret < 0)
			ret = __mlock_posix_error_return(ret);
	} else {
		munlock_vma_pages_range(vma, start, end);
	}
out:
	*prev = vma;
	return ret;
}

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Last-modified: 2014-09-13 (土) 08:26:42