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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 <n-horiguchi@ah.jp.nec.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naoya Horiguchi 2015-02-11 15:25:15 -08:00 committed by Linus Torvalds
parent cfc5115579
commit 61f77eda9b
12 changed files with 23 additions and 141 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/arm/mm/hugetlbpage.c
View File

@ -36,12 +36,6 @@
* of type casting from pmd_t * to pte_t *.
*/
struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write)
{
return ERR_PTR(-EINVAL);
}
int pud_huge(pud_t pud)
{
return 0;

6
arch/arm64/mm/hugetlbpage.c
View File

@ -38,12 +38,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
}
#endif
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 !(pmd_val(pmd) & PMD_TABLE_BIT);

6
arch/ia64/mm/hugetlbpage.c
View File

@ -114,12 +114,6 @@ 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;
}
void hugetlb_free_pgd_range(struct mmu_gather *tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)

6
arch/metag/mm/hugetlbpage.c
View File

@ -94,12 +94,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
return 0;
}
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 pmd_page_shift(pmd) > PAGE_SHIFT;

18
arch/mips/mm/hugetlbpage.c
View File

@ -68,12 +68,6 @@ int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
return 0;
}
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 (pmd_val(pmd) & _PAGE_HUGE) != 0;
@ -83,15 +77,3 @@ int pud_huge(pud_t pud)
{
return (pud_val(pud) & _PAGE_HUGE) != 0;
}
struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
struct page *page;
page = pte_page(*(pte_t *)pmd);
if (page)
page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
return page;
}

8
arch/powerpc/mm/hugetlbpage.c
View File

@ -714,6 +714,14 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
return NULL;
}
struct page *
follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write)
{
BUG();
return NULL;
}
static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
unsigned long sz)
{

20
arch/s390/mm/hugetlbpage.c
View File

@ -192,12 +192,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
return 0;
}
struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write)
{
return ERR_PTR(-EINVAL);
}
int pmd_huge(pmd_t pmd)
{
if (!MACHINE_HAS_HPAGE)
@ -210,17 +204,3 @@ int pud_huge(pud_t pud)
{
return 0;
}
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmdp, int write)
{
struct page *page;
if (!MACHINE_HAS_HPAGE)
return NULL;
page = pmd_page(*pmdp);
if (page)
page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
return page;
}

12
arch/sh/mm/hugetlbpage.c
View File

@ -67,12 +67,6 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
return 0;
}
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;
@ -82,9 +76,3 @@ 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;
}

12
arch/sparc/mm/hugetlbpage.c
View File

@ -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;
}

28
arch/tile/mm/hugetlbpage.c
View File

@ -150,12 +150,6 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
return NULL;
}
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 !!(pmd_val(pmd) & _PAGE_HUGE_PAGE);
@ -166,28 +160,6 @@ int pud_huge(pud_t pud)
return !!(pud_val(pud) & _PAGE_HUGE_PAGE);
}
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
struct page *page;
page = pte_page(*(pte_t *)pmd);
if (page)
page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
return page;
}
struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write)
{
struct page *page;
page = pte_page(*(pte_t *)pud);
if (page)
page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
return page;
}
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
return 0;

12
arch/x86/mm/hugetlbpage.c
View File

@ -52,20 +52,8 @@ 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;
}
#else
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 !!(pmd_val(pmd) & _PAGE_PSE);

30
mm/hugetlb.c
View File

@ -3660,7 +3660,20 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
return (pte_t *) pmd;
}
struct page *
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
/*
* These functions are overwritable if your architecture needs its own
* behavior.
*/
struct page * __weak
follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write)
{
return ERR_PTR(-EINVAL);
}
struct page * __weak
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
@ -3672,7 +3685,7 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
return page;
}
struct page *
struct page * __weak
follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write)
{
@ -3684,19 +3697,6 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
return page;
}
#else /* !CONFIG_ARCH_WANT_GENERAL_HUGETLB */
/* Can be overriden by architectures */
struct page * __weak
follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write)
{
BUG();
return NULL;
}
#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
#ifdef CONFIG_MEMORY_FAILURE
/* Should be called in hugetlb_lock */