When populating mappings backed by contiguous memory allocations
(VM_CONTIG), use the preallocated pages instead of allocating new.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/memory.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index a728bed16c20..fbef78d07cf3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3100,7 +3100,18 @@ static int do_anonymous_page(struct vm_fault *vmf)
/* Allocate our own private page. */
if (unlikely(anon_vma_prepare(vma)))
goto oom;
- page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
+
+ /*
+ * In the special VM_CONTIG case, pages have been pre-allocated. So,
+ * simply grab the appropriate pre-allocated page.
+ */
+ if (unlikely(vma->vm_flags & VM_CONTIG)) {
+ VM_BUG_ON(!vma->vm_private_data);
+ page = ((struct page *)vma->vm_private_data) +
+ ((vmf->address - vma->vm_start) / PAGE_SIZE);
+ } else {
+ page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
+ }
if (!page)
goto oom;
--
2.13.6
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