sparc64: Fix get_user_pages_fast() wrt. THP.

[karo-tx-linux.git] / arch / sparc / mm / gup.c

diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 42c55df3aec300b5baee79e6af5123ab99c7b126..01ee23dd724d5812b7993245b8bcb15bb0a00a7a 100644 (file)
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -66,6 +66,56 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
        return 1;
 }
 
+static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
+                       unsigned long end, int write, struct page **pages,
+                       int *nr)
+{
+       struct page *head, *page, *tail;
+       u32 mask;
+       int refs;
+
+       mask = PMD_HUGE_PRESENT;
+       if (write)
+               mask |= PMD_HUGE_WRITE;
+       if ((pmd_val(pmd) & mask) != mask)
+               return 0;
+
+       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;
+}
+
 static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
                int write, struct page **pages, int *nr)
 {
@@ -77,9 +127,14 @@ 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))
+               if (pmd_none(pmd) || pmd_trans_splitting(pmd))
                        return 0;
-               if (!gup_pte_range(pmd, addr, next, write, pages, nr))
+               if (unlikely(pmd_large(pmd))) {
+                       if (!gup_huge_pmd(pmdp, pmd, addr, next,
+                                         write, pages, nr))
+                               return 0;
+               } else if (!gup_pte_range(pmd, addr, next, write,
+                                         pages, nr))
                        return 0;
        } while (pmdp++, addr = next, addr != end);