#ifdef AS_MODULE
#include <linux/module.h>
#endif
#include <linux/errno.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/mmzone.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/threads.h>

/* Offsets into the range list array */
#define COW_PAGE NR_CPUS
#define NOT_PRESENT (NR_CPUS + 1)

static inline int page2node(struct page *page) {
        struct zone *zone = page_zone(page);
        return zone->zone_pgdat->node_id;
}

int pagemap_show(struct seq_file *s, void *v) {
        struct task_struct *task = s->private;
	struct vm_area_struct *vma;
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *ptep, pte;
        unsigned long pga;
        int n, i, vmac;

	long node_pgc[NOT_PRESENT + 1];

	down_read(&task->active_mm->mmap_sem);
	vmac = 0;
	/* For each VMA, translate each page it spans to a node number */
	for (vma = task->active_mm->mmap; vma; vma = vma->vm_next) {
		seq_printf(s, "VMA %d start %lx end %lx\n", vmac, vma->vm_start,
		       vma->vm_end);
                for (pga = PAGE_ALIGN(vma->vm_start); pga < vma->vm_end; 
		     pga += PAGE_SIZE) {
			n = NOT_PRESENT;
			pgd = pgd_offset(task->active_mm, pga);
			if (pgd_none(*pgd) || pgd_bad(*pgd))
				goto out;
			pmd = pmd_offset(pgd, pga);
			if (pmd_none(*pmd) || pmd_bad(*pmd))
				goto out;
			ptep = pte_offset_map(pmd, pga);
			if (!ptep)
				goto out;
			pte = *ptep;
			pte_unmap(ptep);
			n = page2node(pte_page(pte));
			/* COW-page? Check if mapped to the zero page */
			if (!pte_write(pte) && (vma->vm_flags & VM_SHARED) 
			    && (vma->vm_flags & VM_WRITE)) {
			    seq_printf(s, "%08lx-%08lx node %d COW\n", 
				       pga, pga + PAGE_SIZE - 1, n); 
			}

			else {
			    if (n == NOT_PRESENT)
				seq_printf(s, "%08lx-%08lx node %d not present\n", 
					   pga, pga + PAGE_SIZE - 1, n); 
			    else
				seq_printf(s, "%08lx-%08lx node %d \n", pga, 
					   pga + PAGE_SIZE - 1, n); 
			}
		out:
                }
		vmac++;
        }
	up_read(&task->active_mm->mmap_sem);
	
	return 0;
}