path: root/arch/sparc/mm
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authorNaoya Horiguchi <>2015-02-11 15:25:15 -0800
committerLinus Torvalds <>2015-02-11 17:06:01 -0800
commit61f77eda9bbf0d2e922197ed2dcf88638a639ce5 (patch)
tree4ca42137ea20cf5c48379a87cc0811050f124ee8 /arch/sparc/mm
parentcfc511557945812280699a92f171ddd2d254aca6 (diff)
mm/hugetlb: reduce arch dependent code around follow_huge_*
Currently we have many duplicates in definitions around follow_huge_addr(), follow_huge_pmd(), and follow_huge_pud(), so this patch tries to remove the m. The basic idea is to put the default implementation for these functions in mm/hugetlb.c as weak symbols (regardless of CONFIG_ARCH_WANT_GENERAL_HUGETL B), and to implement arch-specific code only when the arch needs it. For follow_huge_addr(), only powerpc and ia64 have their own implementation, and in all other architectures this function just returns ERR_PTR(-EINVAL). So this patch sets returning ERR_PTR(-EINVAL) as default. As for follow_huge_(pmd|pud)(), if (pmd|pud)_huge() is implemented to always return 0 in your architecture (like in ia64 or sparc,) it's never called (the callsite is optimized away) no matter how implemented it is. So in such architectures, we don't need arch-specific implementation. In some architecture (like mips, s390 and tile,) their current arch-specific follow_huge_(pmd|pud)() are effectively identical with the common code, so this patch lets these architecture use the common code. One exception is metag, where pmd_huge() could return non-zero but it expects follow_huge_pmd() to always return NULL. This means that we need arch-specific implementation which returns NULL. This behavior looks strange to me (because non-zero pmd_huge() implies that the architecture supports PMD-based hugepage, so follow_huge_pmd() can/should return some relevant value,) but that's beyond this cleanup patch, so let's keep it. Justification of non-trivial changes: - in s390, follow_huge_pmd() checks !MACHINE_HAS_HPAGE at first, and this patch removes the check. This is OK because we can assume MACHINE_HAS_HPAGE is true when follow_huge_pmd() can be called (note that pmd_huge() has the same check and always returns 0 for !MACHINE_HAS_HPAGE.) - in s390 and mips, we use HPAGE_MASK instead of PMD_MASK as done in common code. This patch forces these archs use PMD_MASK, but it's OK because they are identical in both archs. In s390, both of HPAGE_SHIFT and PMD_SHIFT are 20. In mips, HPAGE_SHIFT is defined as (PAGE_SHIFT + PAGE_SHIFT - 3) and PMD_SHIFT is define as (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3), but PTE_ORDER is always 0, so these are identical. Signed-off-by: Naoya Horiguchi <> Acked-by: Hugh Dickins <> Cc: James Hogan <> Cc: David Rientjes <> Cc: Mel Gorman <> Cc: Johannes Weiner <> Cc: Michal Hocko <> Cc: Rik van Riel <> Cc: Andrea Arcangeli <> Cc: Luiz Capitulino <> Cc: Nishanth Aravamudan <> Cc: Lee Schermerhorn <> Cc: Steve Capper <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'arch/sparc/mm')
1 files changed, 0 insertions, 12 deletions
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index d329537739c6..4242eab12e10 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -215,12 +215,6 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
return entry;
-struct page *follow_huge_addr(struct mm_struct *mm,
- unsigned long address, int write)
- return ERR_PTR(-EINVAL);
int pmd_huge(pmd_t pmd)
return 0;
@@ -230,9 +224,3 @@ int pud_huge(pud_t pud)
return 0;
-struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
- pmd_t *pmd, int write)
- return NULL;