From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
handle large pages for get_user_pages_fast. Also take care of large page
splitting.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/mm/gup.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 82 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
index d7efdbf..835c1ae 100644
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -55,6 +55,72 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long
addr,
return 1;
}
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int gup_huge_pmd(pmd_t *pmdp, unsigned long addr,
+ unsigned long end, int write,
+ struct page **pages, int *nr)
+{
+ int refs;
+ pmd_t pmd;
+ unsigned long mask;
+ struct page *head, *page, *tail;
+
+ pmd = *pmdp;
+ mask = PMD_HUGE_PRESENT | PMD_HUGE_USER;
+ if (write)
+ mask |= PMD_HUGE_RW;
+
+ if ((pmd_val(pmd) & mask) != mask)
+ return 0;
+
+ /* large pages are never "special" */
+ VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
+
+ refs = 0;
+ head = pmd_page(pmd);
+ page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ tail = page;
+ do {
+ VM_BUG_ON(compound_head(page) != head);
+ pages[*nr] = page;
+ (*nr)++;
+ page++;
+ refs++;
+ } while (addr += PAGE_SIZE, addr != end);
+
+ if (!page_cache_add_speculative(head, refs)) {
+ *nr -= refs;
+ return 0;
+ }
+
+ if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
+ *nr -= refs;
+ while (refs--)
+ put_page(head);
+ return 0;
+ }
+ /*
+ * Any tail page need their mapcount reference taken before we
+ * return.
+ */
+ while (refs--) {
+ if (PageTail(tail))
+ get_huge_page_tail(tail);
+ tail++;
+ }
+
+ return 1;
+}
+#else
+
+static inline int gup_huge_pmd(pmd_t *pmdp, unsigned long addr,
+ unsigned long end, int write,
+ struct page **pages, int *nr)
+{
+ return 1;
+}
+#endif
+
static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
@@ -66,9 +132,23 @@ static int gup_pmd_range(pud_t pud, unsigned long addr,
unsigned long end,
pmd_t pmd = *pmdp;
next = pmd_addr_end(addr, end);
- if (pmd_none(pmd))
+ /*
+ * The pmd_trans_splitting() check below explains why
+ * pmdp_splitting_flush has to flush the tlb, to stop
+ * this gup-fast code from running while we set the
+ * splitting bit in the pmd. Returning zero will take
+ * the slow path that will call wait_split_huge_page()
+ * if the pmd is still in splitting state. gup-fast
+ * can't because it has irq disabled and
+ * wait_split_huge_page() would never return as the
+ * tlb flush IPI wouldn't run.
+ */
+ if (pmd_none(pmd) || pmd_trans_splitting(pmd))
return 0;
- if (is_hugepd(pmdp)) {
+ if (unlikely(pmd_large(pmd))) {
+ if (!gup_huge_pmd(pmdp, addr, next, write, pages, nr))
+ return 0;
+ } else if (is_hugepd(pmdp)) {
if (!gup_hugepd((hugepd_t *)pmdp, PMD_SHIFT,
addr, next, write, pages, nr))
return 0;
--
1.7.10
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