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Diffstat (limited to 'arch/x86/mm/gup.c')
-rw-r--r--arch/x86/mm/gup.c28
1 files changed, 27 insertions, 1 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 738e6593799d..dbe34b931374 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -8,6 +8,7 @@
#include <linux/mm.h>
#include <linux/vmstat.h>
#include <linux/highmem.h>
+#include <linux/swap.h>
#include <asm/pgtable.h>
@@ -89,6 +90,7 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
page = pte_page(pte);
get_page(page);
+ SetPageReferenced(page);
pages[*nr] = page;
(*nr)++;
@@ -103,6 +105,17 @@ static inline void get_head_page_multiple(struct page *page, int nr)
VM_BUG_ON(page != compound_head(page));
VM_BUG_ON(page_count(page) == 0);
atomic_add(nr, &page->_count);
+ SetPageReferenced(page);
+}
+
+static inline void get_huge_page_tail(struct page *page)
+{
+ /*
+ * __split_huge_page_refcount() cannot run
+ * from under us.
+ */
+ VM_BUG_ON(atomic_read(&page->_count) < 0);
+ atomic_inc(&page->_count);
}
static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
@@ -128,6 +141,8 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
+ if (PageTail(page))
+ get_huge_page_tail(page);
(*nr)++;
page++;
refs++;
@@ -148,7 +163,18 @@ 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 (unlikely(pmd_large(pmd))) {
if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))