Just a nit
On Fri 27-07-12 11:46:05, Mel Gorman wrote:
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index fd1d530..8c6e5a5 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2429,6 +2429,25 @@ again:
> tlb_end_vma(tlb, vma);
> }
>
I would welcome a comment here. Something like:
/*
* Called when the VMA is on the way out and page tables will be freed
* by free_pagetables.
* i_mmap_mutex has to be held when calling this function
*/
> +void __unmap_hugepage_range_final(struct mmu_gather *tlb,
> + struct vm_area_struct *vma, unsigned long start,
> + unsigned long end, struct page *ref_page)
> +{
> + __unmap_hugepage_range(tlb, vma, start, end, ref_page);
> +
> + /*
> + * Clear this flag so that x86's huge_pmd_share page_table_shareable
> + * test will fail on a vma being torn down, and not grab a page table
> + * on its way out. We're lucky that the flag has such an appropriate
> + * name, and can in fact be safely cleared here. We could clear it
> + * before the __unmap_hugepage_range above, but all that's necessary
> + * is to clear it before releasing the i_mmap_mutex. This works
> + * because in the context this is called, the VMA is about to be
> + * destroyed and the i_mmap_mutex is held.
> + */
> + vma->vm_flags &= ~VM_MAYSHARE;
> +}
> +
--
Michal Hocko
SUSE Labs
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