Re: [PATCH -V6 04/14] hugetlb: Use mmu_gather instead of atemporary linked list for accumulating pages

From: Andrew Morton
Date: Mon Apr 23 2012 - 19:44:45 EST


On Mon, 16 Apr 2012 16:14:41 +0530
"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:

> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> Use mmu_gather instead of temporary linked list for accumulating pages when
> we unmap a hugepage range. This also allows us to get rid of i_mmap_mutex
> unmap_hugepage_range in the following patch.
>

Another warning and a build error, due to inadequate coverage testing.

mm/memory.c: In function 'unmap_single_vma':
mm/memory.c:1334: error: implicit declaration of function '__unmap_hugepage_range'

--- a/include/linux/hugetlb.h~hugetlb-use-mmu_gather-instead-of-a-temporary-linked-list-for-accumulating-pages-fix
+++ a/include/linux/hugetlb.h
@@ -41,8 +41,9 @@ int follow_hugetlb_page(struct mm_struct
unsigned long *, int *, int, unsigned int flags);
void unmap_hugepage_range(struct vm_area_struct *,
unsigned long, unsigned long, struct page *);
-void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *,
- unsigned long, unsigned long, struct page *);
+void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vms,
+ unsigned long start, unsigned long end,
+ struct page *ref_page);
int hugetlb_prefault(struct address_space *, struct vm_area_struct *);
void hugetlb_report_meminfo(struct seq_file *);
int hugetlb_report_node_meminfo(int, char *);
@@ -119,6 +120,12 @@ static inline void copy_huge_page(struct

#define hugetlb_change_protection(vma, address, end, newprot)

+static inline void __unmap_hugepage_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, struct page *ref_page)
+{
+}
+
#endif /* !CONFIG_HUGETLB_PAGE */

#define HUGETLB_ANON_FILE "anon_hugepage"


I also fixed up that __unmap_hugepage_range() declaration - it's quite
maddening to work on and review and read code when people have gone and
left out the names of the arguments.

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