On Tue, Aug 09, 2016 at 01:34:35PM +0100, Steve Capper wrote:
> In page_remove_file_rmap(.) we have the following check:
> VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
>
> This is meant to check for either HugeTLB pages or THP when a compound
> page is passed in.
>
> Unfortunately, if one disables CONFIG_TRANSPARENT_HUGEPAGE, then
> PageTransHuge(.) will always return false provoking BUGs when one runs
> the libhugetlbfs test suite.
>
> Changing the definition of PageTransHuge to be defined for
> !CONFIG_TRANSPARENT_HUGEPAGE turned out to provoke build bugs; so this
> patch instead replaces the errant check with:
> PageTransHuge(page) || PageHuge(page)
I think PageHead() check should be enough to cover this.
>
> Fixes: dd78fedde4b9 ("rmap: support file thp")
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Steve Capper <steve.capper@xxxxxxx>
> ---
> mm/rmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 709bc83..ad8fc51 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1303,7 +1303,7 @@ static void page_remove_file_rmap(struct page *page, bool compound)
> {
> int i, nr = 1;
>
> - VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
> + VM_BUG_ON_PAGE(compound && !(PageTransHuge(page) || PageHuge(page)), page);
> lock_page_memcg(page);
>
> /* Hugepages are not counted in NR_FILE_MAPPED for now. */
> --
> 1.8.3.1
>
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--
Kirill A. Shutemov
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