Re: [PATCH 1/2] mm: hugetlbfs: Add some VM_BUG_ON()s tocatchnon-hugetlbfs pages

[Naoya Horiguchi]

On Mon, Oct 28, 2013 at 03:16:18PM -0700, Dave Hansen wrote:
> 
> Dave Jiang reported that he was seeing oopses when running
> NUMA systems and default_hugepagesz=1G.  I traced the issue down
> to migrate_page_copy() trying to use the same code for hugetlb
> pages and transparent hugepages.  It should not have been trying
> to pass thp pages in there.
> 
> So, add some VM_BUG_ON()s for the next hapless VM developer that

Looks good to me, thanks.

Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>


> 
> ---
> 
>  linux.git-davehans/include/linux/hugetlb.h |    1 +
>  linux.git-davehans/mm/hugetlb.c            |    1 +
>  2 files changed, 2 insertions(+)
> 
> diff -puN include/linux/hugetlb.h~bug-not-hugetlbfs-in-copy_huge_page include/linux/hugetlb.h
> --- linux.git/include/linux/hugetlb.h~bug-not-hugetlbfs-in-copy_huge_page	2013-10-28 15:06:12.888828815 -0700
> +++ linux.git-davehans/include/linux/hugetlb.h	2013-10-28 15:06:12.893829038 -0700
> @@ -355,6 +355,7 @@ static inline pte_t arch_make_huge_pte(p
>  
>  static inline struct hstate *page_hstate(struct page *page)
>  {
> +	VM_BUG_ON(!PageHuge(page));
>  	return size_to_hstate(PAGE_SIZE << compound_order(page));
>  }
>  
> diff -puN mm/hugetlb.c~bug-not-hugetlbfs-in-copy_huge_page mm/hugetlb.c
> --- linux.git/mm/hugetlb.c~bug-not-hugetlbfs-in-copy_huge_page	2013-10-28 15:06:12.890828904 -0700
> +++ linux.git-davehans/mm/hugetlb.c	2013-10-28 15:06:12.894829082 -0700
> @@ -498,6 +498,7 @@ void copy_huge_page(struct page *dst, st
>  	int i;
>  	struct hstate *h = page_hstate(src);
>  
> +	VM_BUG_ON(!h);
>  	if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
>  		copy_gigantic_page(dst, src);
>  		return;
> _
> 
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