int hugetlb_max_hstate __read_mostly;
unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];
+/*
+ * Minimum page order among possible hugepage sizes, set to a proper value
+ * at boot time.
+ */
+static unsigned int minimum_order __read_mostly = UINT_MAX;
__initdata LIST_HEAD(huge_boot_pages);
* Region tracking -- allows tracking of reservations and instantiated pages
* across the pages in a mapping.
*
- * The region data structures are embedded into a resv_map and
- * protected by a resv_map's lock
+ * The region data structures are embedded into a resv_map and protected
+ * by a resv_map's lock. The set of regions within the resv_map represent
+ * reservations for huge pages, or huge pages that have already been
+ * instantiated within the map. The from and to elements are huge page
+ * indicies into the associated mapping. from indicates the starting index
+ * of the region. to represents the first index past the end of the region.
+ *
+ * For example, a file region structure with from == 0 and to == 4 represents
+ * four huge pages in a mapping. It is important to note that the to element
+ * represents the first element past the end of the region. This is used in
+ * arithmetic as 4(to) - 0(from) = 4 huge pages in the region.
+ *
+ * Interval notation of the form [from, to) will be used to indicate that
+ * the endpoint from is inclusive and to is exclusive.
*/
struct file_region {
struct list_head link;
long to;
};
+/*
+ * Add the huge page range represented by [f, t) to the reserve
+ * map. Existing regions will be expanded to accommodate the
+ * specified range. We know only existing regions need to be
+ * expanded, because region_add is only called after region_chg
+ * with the same range. If a new file_region structure must
+ * be allocated, it is done in region_chg.
+ */
static long region_add(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
return 0;
}
+/*
+ * Examine the existing reserve map and determine how many
+ * huge pages in the specified range [f, t) are NOT currently
+ * represented. This routine is called before a subsequent
+ * call to region_add that will actually modify the reserve
+ * map to add the specified range [f, t). region_chg does
+ * not change the number of huge pages represented by the
+ * map. However, if the existing regions in the map can not
+ * be expanded to represent the new range, a new file_region
+ * structure is added to the map as a placeholder. This is
+ * so that the subsequent region_add call will have all the
+ * regions it needs and will not fail.
+ *
+ * Returns the number of huge pages that need to be added
+ * to the existing reservation map for the range [f, t).
+ * This number is greater or equal to zero. -ENOMEM is
+ * returned if a new file_region structure is needed and can
+ * not be allocated.
+ */
static long region_chg(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
return chg;
}
+/*
+ * Truncate the reserve map at index 'end'. Modify/truncate any
+ * region which contains end. Delete any regions past end.
+ * Return the number of huge pages removed from the map.
+ */
static long region_truncate(struct resv_map *resv, long end)
{
struct list_head *head = &resv->regions;
return chg;
}
+/*
+ * Count and return the number of huge pages in the reserve map
+ * that intersect with the range [f, t).
+ */
static long region_count(struct resv_map *resv, long f, long t)
{
struct list_head *head = &resv->regions;
*/
void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
{
- unsigned int order = 8 * sizeof(void *);
unsigned long pfn;
- struct hstate *h;
if (!hugepages_supported())
return;
- /* Set scan step to minimum hugepage size */
- for_each_hstate(h)
- if (order > huge_page_order(h))
- order = huge_page_order(h);
- VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order));
- for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
+ VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << minimum_order));
+ for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
dissolve_free_huge_page(pfn_to_page(pfn));
}
struct hstate *h;
for_each_hstate(h) {
+ if (minimum_order > huge_page_order(h))
+ minimum_order = huge_page_order(h);
+
/* oversize hugepages were init'ed in early boot */
if (!hstate_is_gigantic(h))
hugetlb_hstate_alloc_pages(h);
}
+ VM_BUG_ON(minimum_order == UINT_MAX);
}
static char * __init memfmt(char *buf, unsigned long n)
{
return NULL;
}
+
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+ return 0;
+}
#define want_pmd_share() (0)
#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */