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-rw-r--r--mm/hugetlb.c25
1 files changed, 18 insertions, 7 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 41b1038f76d..d5987a87bbe 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -13,6 +13,7 @@
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
+#include <linux/mutex.h>
#include <asm/page.h>
#include <asm/pgtable.h>
@@ -26,6 +27,10 @@ unsigned long max_huge_pages;
static struct list_head hugepage_freelists[MAX_NUMNODES];
static unsigned int nr_huge_pages_node[MAX_NUMNODES];
static unsigned int free_huge_pages_node[MAX_NUMNODES];
+/*
+ * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
+ */
+static DEFINE_SPINLOCK(hugetlb_lock);
static void clear_huge_page(struct page *page, unsigned long addr)
{
@@ -50,11 +55,6 @@ static void copy_huge_page(struct page *dst, struct page *src,
}
}
-/*
- * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
- */
-static DEFINE_SPINLOCK(hugetlb_lock);
-
static void enqueue_huge_page(struct page *page)
{
int nid = page_to_nid(page);
@@ -508,14 +508,24 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
pte_t *ptep;
pte_t entry;
int ret;
+ static DEFINE_MUTEX(hugetlb_instantiation_mutex);
ptep = huge_pte_alloc(mm, address);
if (!ptep)
return VM_FAULT_OOM;
+ /*
+ * Serialize hugepage allocation and instantiation, so that we don't
+ * get spurious allocation failures if two CPUs race to instantiate
+ * the same page in the page cache.
+ */
+ mutex_lock(&hugetlb_instantiation_mutex);
entry = *ptep;
- if (pte_none(entry))
- return hugetlb_no_page(mm, vma, address, ptep, write_access);
+ if (pte_none(entry)) {
+ ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
+ mutex_unlock(&hugetlb_instantiation_mutex);
+ return ret;
+ }
ret = VM_FAULT_MINOR;
@@ -525,6 +535,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (write_access && !pte_write(entry))
ret = hugetlb_cow(mm, vma, address, ptep, entry);
spin_unlock(&mm->page_table_lock);
+ mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}