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authorDavid S. Miller <davem@davemloft.net>2013-02-13 12:21:06 -0800
committerDavid S. Miller <davem@davemloft.net>2013-02-13 12:22:14 -0800
commit89a77915e0f56dc7b9f9082ba787895b6a83f809 (patch)
treece147ee36f1117dddeac5e1ba53eab9986b1f47b /arch/sparc/mm
parentb9156ebb7beef015745f917f373abc137efc3400 (diff)
sparc64: Fix get_user_pages_fast() wrt. THP.
Mostly mirrors the s390 logic, as unlike x86 we don't need the SetPageReferenced() bits. On sparc64 we also lack a user/privileged bit in the huge PMDs. In order to make this work for THP and non-THP builds, some header file adjustments were necessary. Namely, provide the PMD_HUGE_* bit defines and the pmd_large() inline unconditionally rather than protected by TRANSPARENT_HUGEPAGE. Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/mm')
-rw-r--r--arch/sparc/mm/gup.c59
1 files changed, 57 insertions, 2 deletions
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 42c55df3aec3..01ee23dd724d 100644
--- 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);

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