--- arch/x86/mm/ioremap.c.orig  2009-12-03 04:51:21.000000000 +0100
+++ arch/x86/mm/ioremap.c       2010-07-02 10:05:24.330120000 +0200
@@ -1,4 +1,4 @@
-/*
+*
  * Re-map IO memory to kernel address space so that we can access it.
  * This is needed for high PCI addresses that aren't mapped in the
  * 640k-1MB IO memory area on PC's
@@ -138,12 +138,12 @@
         * Don't allow anybody to remap normal RAM that we're using..
         */
        for (pfn = phys_addr >> PAGE_SHIFT;
-                               (pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK);
+                               (pfn << PAGE_SHIFT) <= (last_addr & PAGE_MASK);
                                pfn++) {
 
                int is_ram = page_is_ram(pfn);
 
-               if (is_ram && pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))
+               if (is_ram && pfn_valid(pfn) && PageReserved(pfn_to_page(pfn)))
                        return NULL;
                WARN_ON_ONCE(is_ram);
        }

Quote:

600typedef struct pglist_data {
601 struct zone node_zones[MAX_NR_ZONES];
602 struct zonelist node_zonelists[MAX_ZONELISTS];
603 int nr_zones;
604#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
605 struct page *node_mem_map;
606#ifdef CONFIG_CGROUP_MEM_RES_CTLR
607 struct page_cgroup *node_page_cgroup;
608#endif
609#endif
610#ifndef CONFIG_NO_BOOTMEM
611 struct bootmem_data *bdata;
612#endif
613#ifdef CONFIG_MEMORY_HOTPLUG
614 /*
615 * Must be held any time you expect node_start_pfn, node_present_pages
616 * or node_spanned_pages stay constant. Holding this will also
617 * guarantee that any pfn_valid() stays that way.
618 *
619 * Nests above zone->lock and zone->size_seqlock.
620 */
621 spinlock_t node_size_lock;
622#endif
623 unsigned long node_start_pfn;
624 unsigned long node_present_pages; /* total number of physical pages */
625 unsigned long node_spanned_pages; /* total size of physical page
626 range, including holes */
627 int node_id;
628 wait_queue_head_t kswapd_wait;
629 struct task_struct *kswapd;
630 int kswapd_max_order;
631} pg_data_t;

    void *mem;
    while (1) {
        mem = (void *) malloc(1024 * 1024); //1MB
        if  (!mem) {
            dump_mem_info(); //Prints total memory malloced using details from /proc/<pid>/status
            break;  
    }

/**
 * Create an offer to the specified process for the given range of address space.
 * The address space must be a whole multiple of pages.
 * The address space must be validly mapped for the current process.
 * Changes specified by this function do not occur until the remote process
 *   accepts the offer.
 * An offer can be cancelled by offering the same address with a size of 0.
 *   If the target process has already accepted the offer, it is too late, and the
 *   call will simply fail as this address is no longer valid for the current process.
 * If all permissions are dropped, then the memory is unmapped from the current
 *   process when the offer is claimed.
 * Flags:
 *    VMO_GRANT_R - grant read access to the remote process
 *    VMO_GRANT_W - grant write access to the remote process
 *    VMO_GRANT_X - grant exec access to the remote process
 *    VMO_DROP_R - release this process' read permission for the pages
 *    VMO_DROP_W - release this process' write permission for the pages
 *    VMO_DROP_X - release this process' exec permission for the pages
 *
 *    VMO_DISOWN - combination of all "drop" flags
 *    VMO_GRANTALL - combination of all "grant" flags
 */
int vm_offer(int dest_pid, void *addr, int len, int flags);

/**
 * Receive an offer of VM pages from another process.
 * The offer must have already been made by the source process.
 * The offer is identified (from other offers made by that process) by specifying the remote virtual address.
 * Flags:
 *   (none, yet)
 */
int vm_claim(int src_pid, void *remote_addr, void **local_addr, int *size, int flags);

/**
 * List sent and received offers.
 * list is a buffer to which an array of offer records will be written
 * count should be initialized to the size (in records) of the list
 * upon successful return, list is populated, and count is the number of entries
 * upon failure, list is unaltered and count is the number of entries needed in order to return successfully
 * Note that offers are dynamic in nature and may change before the entries can be acted on.
 */
int vm_listoffer(vm_offer_t *list, int *count);

Quote:

Register set is easy to do, as long as you know where it is. On Linux, there is a simple connection between the locations of process' task structure and its register set location:

Assuming struct task_struct *p is a pointer to the task structure, then the corresponding register set location is:

struct pt_regs *regs = ((struct pt_regs *)(2*PAGE_SIZE + (unsigned long)p)) - 1;