[RFC PATCH 2/3] mm/map_contig: Use pre-allocated pages for VM_CONTIG mappings
From: Mike Kravetz <hidden>
Date: 2017-10-12 01:47:04
Also in:
linux-mm, lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
When populating mappings backed by contiguous memory allocations (VM_CONTIG), use the preallocated pages instead of allocating new. Signed-off-by: Mike Kravetz <redacted> --- 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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