static int unmerge_ksm_pages(struct vm_area_struct *vma,
			     unsigned long start, unsigned long end)
{
	unsigned long addr;
	int err = 0;

	for (addr = start; addr < end && !err; addr += PAGE_SIZE) {
		if (ksm_test_exit(vma->vm_mm))
			break;
		if (signal_pending(current))
			err = -ERESTARTSYS;
		else
			err = break_ksm(vma, addr);
	}
	return err;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.