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Subject[PATCH 1/4] powerpc: remove superfluous PageTail checks on the pte gup_fast
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This part of gup_fast doesn't seem capable of handling hugetlbfs ptes,
those should be handled by gup_hugepd only, so these checks are
superfluous.

Plus if this wasn't a noop, it would have oopsed because, the insistence
of using the speculative refcounting would trigger a VM_BUG_ON if a tail
page was encountered in the page_cache_get_speculative().

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>

diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
index b9e1c7f..d7efdbf 100644
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -16,17 +16,6 @@

#ifdef __HAVE_ARCH_PTE_SPECIAL

-static inline void get_huge_page_tail(struct page *page)
-{
- /*
- * __split_huge_page_refcount() cannot run
- * from under us.
- */
- VM_BUG_ON(page_mapcount(page) < 0);
- VM_BUG_ON(atomic_read(&page->_count) != 0);
- atomic_inc(&page->_mapcount);
-}
-
/*
* The performance critical leaf functions are made noinline otherwise gcc
* inlines everything into a single function which results in too much
@@ -58,8 +47,6 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
put_page(page);
return 0;
}
- if (PageTail(page))
- get_huge_page_tail(page);
pages[*nr] = page;
(*nr)++;

--
1.7.3.4


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