Patch "mm/hugetlb: reduce arch dependent code around follow_huge_*" has been added to the 3.19-stable tree

PATCH [email protected] 1 participant 1 message Apr 26, 2015

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Stable branch Memory management Arm (32-bit) x86 +9 more subsystems

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2015-04-26 09:57 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

mm/hugetlb: reduce arch dependent code around follow_huge_*

to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-hugetlb-reduce-arch-dependent-code-around-follow_huge_.patch
and it can be found in the queue-3.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 61f77eda9bbf0d2e922197ed2dcf88638a639ce5 Mon Sep 17 00:00:00 2001

From: Naoya Horiguchi <[email protected]>
Date: Wed, 11 Feb 2015 15:25:15 -0800
Subject: mm/hugetlb: reduce arch dependent code around follow_huge_*

From: Naoya Horiguchi <[email protected]>

commit 61f77eda9bbf0d2e922197ed2dcf88638a639ce5 upstream.

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.

[[email protected]: resolve conflict to apply to v3.19.1]

Signed-off-by Naoya Horiguchi <[email protected]>

Acked-by Hugh Dickins <[email protected]>

Cc James Hogan <[email protected]>

Cc David Rientjes <[email protected]>

Cc Mel Gorman <[email protected]>

Cc Johannes Weiner <[email protected]>

Cc Michal Hocko <[email protected]>

Cc Rik van Riel <[email protected]>

Cc Andrea Arcangeli <[email protected]>

Cc Luiz Capitulino <[email protected]>

Cc Nishanth Aravamudan <[email protected]>

Cc Lee Schermerhorn <[email protected]>

Cc Steve Capper <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

Signed-off-by Linus Torvalds <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 arch/arm/mm/hugetlbpage.c     |    6 ------
 arch/arm64/mm/hugetlbpage.c   |    6 ------
 arch/ia64/mm/hugetlbpage.c    |    6 ------
 arch/metag/mm/hugetlbpage.c   |    6 ------
 arch/mips/mm/hugetlbpage.c    |   18 ------------------
 arch/powerpc/mm/hugetlbpage.c |    8 ++++++++
 arch/s390/mm/hugetlbpage.c    |   20 --------------------
 arch/sh/mm/hugetlbpage.c      |   12 ------------
 arch/sparc/mm/hugetlbpage.c   |   12 ------------
 arch/tile/mm/hugetlbpage.c    |   28 ----------------------------
 arch/x86/mm/hugetlbpage.c     |   12 ------------
 mm/hugetlb.c                  |   30 +++++++++++++++---------------
 12 files changed, 23 insertions(+), 141 deletions(-)

arch/arm/mm/hugetlbpage.c +0 -6

@@ -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;

arch/arm64/mm/hugetlbpage.c +0 -6

@@ -38,12 +38,6 @@ int huge_pmd_unshare(struct mm_struct *m
 }
 #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);

arch/ia64/mm/hugetlbpage.c +0 -6

@@ -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)

arch/metag/mm/hugetlbpage.c +0 -6

@@ -94,12 +94,6 @@ int huge_pmd_unshare(struct mm_struct *m
 	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;

arch/mips/mm/hugetlbpage.c +0 ~~-18~~

@@ -68,12 +68,6 @@ int is_aligned_hugepage_range(unsigned l
 	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;
-}

arch/powerpc/mm/hugetlbpage.c +8 -0

@@ -714,6 +714,14 @@ follow_huge_pmd(struct mm_struct *mm, un
 	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)
 {

arch/s390/mm/hugetlbpage.c +0 ~~-20~~

@@ -192,12 +192,6 @@ int huge_pmd_unshare(struct mm_struct *m
 	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;
-}

arch/sh/mm/hugetlbpage.c +0 ~~-12~~

@@ -67,12 +67,6 @@ int huge_pmd_unshare(struct mm_struct *m
 	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;
-}

arch/sparc/mm/hugetlbpage.c +0 ~~-12~~

@@ -215,12 +215,6 @@ pte_t huge_ptep_get_and_clear(struct mm_
 	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;
-}

arch/tile/mm/hugetlbpage.c +0 ~~-28~~

@@ -150,12 +150,6 @@ pte_t *huge_pte_offset(struct mm_struct
 	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;

arch/x86/mm/hugetlbpage.c +0 ~~-12~~

@@ -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);
-}
-
 /*
  * pmd_huge() returns 1 if @pmd is hugetlb related entry, that is normal
  * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry.

mm/hugetlb.c +15 ~~-15~~

@@ -3700,7 +3700,20 @@ pte_t *huge_pte_offset(struct mm_struct
 	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)
 {

@@ -3714,7 +3727,7 @@ follow_huge_pmd(struct mm_struct *mm, un
 	return page;
 }
 
-struct page *
+struct page * __weak
 follow_huge_pud(struct mm_struct *mm, unsigned long address,
 		pud_t *pud, int write)
 {

@@ -3726,19 +3739,6 @@ follow_huge_pud(struct mm_struct *mm, un
 	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 */

Patches currently in stable-queue which might be from [email protected] are

queue-3.19/mm-hugetlb-take-page-table-lock-in-follow_huge_pmd.patch queue-3.19/mm-hugetlb-reduce-arch-dependent-code-around-follow_huge_.patch