[PATCH v2 0/9] HugeTLB migration support for PPC64

[PATCH v2 0/9] HugeTLB migration support for PPC64

[Aneesh Kumar K.V]

HugeTLB migration support for PPC64

Changes from V1:
* Added Reviewed-by:
* Drop follow_huge_addr from powerpc

Aneesh Kumar K.V (8):
  mm/hugetlb/migration: Use set_huge_pte_at instead of set_pte_at
  mm/follow_page_mask: Split follow_page_mask to smaller functions.
  mm/hugetlb: export hugetlb_entry_migration helper
  mm/hugetlb: Move default definition of hugepd_t earlier in the header
  mm/follow_page_mask: Add support for hugepage directory entry
  powerpc/hugetlb: Add follow_huge_pd implementation for ppc64.
  powerpc/mm/hugetlb: Remove follow_huge_addr for powerpc
  powerpc/hugetlb: Enable hugetlb migration for ppc64

Anshuman Khandual (1):
  mm/follow_page_mask: Add support for hugetlb pgd entries.

 arch/powerpc/mm/hugetlbpage.c          |  81 ++++++--------
 arch/powerpc/platforms/Kconfig.cputype |   5 +
 include/linux/hugetlb.h                |  56 ++++++----
 mm/gup.c                               | 186 +++++++++++++++++++++++----------
 mm/hugetlb.c                           |  25 ++++-
 mm/migrate.c                           |  21 ++--
 6 files changed, 230 insertions(+), 144 deletions(-)

-- 
2.7.4

[PATCH v2 1/9] mm/hugetlb/migration: Use set_huge_pte_at instead of set_pte_at

[Aneesh Kumar K.V]

The right interface to use to set a hugetlb pte entry is set_huge_pte_at. Use
that instead of set_pte_at.

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/migrate.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 9a0897a14d37..4c272ac6fe53 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -224,25 +224,26 @@ static int remove_migration_pte(struct page *page, struct vm_area_struct *vma,
 		if (is_write_migration_entry(entry))
 			pte = maybe_mkwrite(pte, vma);
 
+		flush_dcache_page(new);
 #ifdef CONFIG_HUGETLB_PAGE
 		if (PageHuge(new)) {
 			pte = pte_mkhuge(pte);
 			pte = arch_make_huge_pte(pte, vma, new, 0);
-		}
-#endif
-		flush_dcache_page(new);
-		set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
-
-		if (PageHuge(new)) {
+			set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 			if (PageAnon(new))
 				hugepage_add_anon_rmap(new, vma, pvmw.address);
 			else
 				page_dup_rmap(new, true);
-		} else if (PageAnon(new))
-			page_add_anon_rmap(new, vma, pvmw.address, false);
-		else
-			page_add_file_rmap(new, false);
+		} else
+#endif
+		{
+			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 
+			if (PageAnon(new))
+				page_add_anon_rmap(new, vma, pvmw.address, false);
+			else
+				page_add_file_rmap(new, false);
+		}
 		if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
 			mlock_vma_page(new);
 
-- 
2.7.4

[PATCH v2 2/9] mm/follow_page_mask: Split follow_page_mask to smaller functions.

[Aneesh Kumar K.V]

Makes code reading easy. No functional changes in this patch. In a followup
patch, we will be updating the follow_page_mask to handle hugetlb hugepd format
so that archs like ppc64 can switch to the generic version. This split helps
in doing that nicely.

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/gup.c | 148 +++++++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 91 insertions(+), 57 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 04aa405350dc..73d46f9f7b81 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -208,68 +208,16 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	return no_page_table(vma, flags);
 }
 
-/**
- * follow_page_mask - look up a page descriptor from a user-virtual address
- * @vma: vm_area_struct mapping @address
- * @address: virtual address to look up
- * @flags: flags modifying lookup behaviour
- * @page_mask: on output, *page_mask is set according to the size of the page
- *
- * @flags can have FOLL_ flags set, defined in <linux/mm.h>
- *
- * Returns the mapped (struct page *), %NULL if no mapping exists, or
- * an error pointer if there is a mapping to something not represented
- * by a page descriptor (see also vm_normal_page()).
- */
-struct page *follow_page_mask(struct vm_area_struct *vma,
-			      unsigned long address, unsigned int flags,
-			      unsigned int *page_mask)
+static struct page *follow_pmd_mask(struct vm_area_struct *vma,
+				    unsigned long address, pud_t *pudp,
+				    unsigned int flags, unsigned int *page_mask)
 {
-	pgd_t *pgd;
-	p4d_t *p4d;
-	pud_t *pud;
 	pmd_t *pmd;
 	spinlock_t *ptl;
 	struct page *page;
 	struct mm_struct *mm = vma->vm_mm;
 
-	*page_mask = 0;
-
-	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
-	if (!IS_ERR(page)) {
-		BUG_ON(flags & FOLL_GET);
-		return page;
-	}
-
-	pgd = pgd_offset(mm, address);
-	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
-		return no_page_table(vma, flags);
-	p4d = p4d_offset(pgd, address);
-	if (p4d_none(*p4d))
-		return no_page_table(vma, flags);
-	BUILD_BUG_ON(p4d_huge(*p4d));
-	if (unlikely(p4d_bad(*p4d)))
-		return no_page_table(vma, flags);
-	pud = pud_offset(p4d, address);
-	if (pud_none(*pud))
-		return no_page_table(vma, flags);
-	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
-		page = follow_huge_pud(mm, address, pud, flags);
-		if (page)
-			return page;
-		return no_page_table(vma, flags);
-	}
-	if (pud_devmap(*pud)) {
-		ptl = pud_lock(mm, pud);
-		page = follow_devmap_pud(vma, address, pud, flags);
-		spin_unlock(ptl);
-		if (page)
-			return page;
-	}
-	if (unlikely(pud_bad(*pud)))
-		return no_page_table(vma, flags);
-
-	pmd = pmd_offset(pud, address);
+	pmd = pmd_offset(pudp, address);
 	if (pmd_none(*pmd))
 		return no_page_table(vma, flags);
 	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
@@ -319,13 +267,99 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 		return ret ? ERR_PTR(ret) :
 			follow_page_pte(vma, address, pmd, flags);
 	}
-
 	page = follow_trans_huge_pmd(vma, address, pmd, flags);
 	spin_unlock(ptl);
 	*page_mask = HPAGE_PMD_NR - 1;
 	return page;
 }
 
+
+static struct page *follow_pud_mask(struct vm_area_struct *vma,
+				    unsigned long address, p4d_t *p4dp,
+				    unsigned int flags, unsigned int *page_mask)
+{
+	pud_t *pud;
+	spinlock_t *ptl;
+	struct page *page;
+	struct mm_struct *mm = vma->vm_mm;
+
+	pud = pud_offset(p4dp, address);
+	if (pud_none(*pud))
+		return no_page_table(vma, flags);
+	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
+		page = follow_huge_pud(mm, address, pud, flags);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
+	if (pud_devmap(*pud)) {
+		ptl = pud_lock(mm, pud);
+		page = follow_devmap_pud(vma, address, pud, flags);
+		spin_unlock(ptl);
+		if (page)
+			return page;
+	}
+	if (unlikely(pud_bad(*pud)))
+		return no_page_table(vma, flags);
+
+	return follow_pmd_mask(vma, address, pud, flags, page_mask);
+}
+
+
+static struct page *follow_p4d_mask(struct vm_area_struct *vma,
+				    unsigned long address, pgd_t *pgdp,
+				    unsigned int flags, unsigned int *page_mask)
+{
+	p4d_t *p4d;
+
+	p4d = p4d_offset(pgdp, address);
+	if (p4d_none(*p4d))
+		return no_page_table(vma, flags);
+	BUILD_BUG_ON(p4d_huge(*p4d));
+	if (unlikely(p4d_bad(*p4d)))
+		return no_page_table(vma, flags);
+
+	return follow_pud_mask(vma, address, p4d, flags, page_mask);
+}
+
+/**
+ * follow_page_mask - look up a page descriptor from a user-virtual address
+ * @vma: vm_area_struct mapping @address
+ * @address: virtual address to look up
+ * @flags: flags modifying lookup behaviour
+ * @page_mask: on output, *page_mask is set according to the size of the page
+ *
+ * @flags can have FOLL_ flags set, defined in <linux/mm.h>
+ *
+ * Returns the mapped (struct page *), %NULL if no mapping exists, or
+ * an error pointer if there is a mapping to something not represented
+ * by a page descriptor (see also vm_normal_page()).
+ */
+struct page *follow_page_mask(struct vm_area_struct *vma,
+			      unsigned long address, unsigned int flags,
+			      unsigned int *page_mask)
+{
+	pgd_t *pgd;
+	struct page *page;
+	struct mm_struct *mm = vma->vm_mm;
+
+	*page_mask = 0;
+
+	/* make this handle hugepd */
+	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
+	if (!IS_ERR(page)) {
+		BUG_ON(flags & FOLL_GET);
+		return page;
+	}
+
+	pgd = pgd_offset(mm, address);
+
+	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+		return no_page_table(vma, flags);
+
+	return follow_p4d_mask(vma, address, pgd, flags, page_mask);
+}
+
 static int get_gate_page(struct mm_struct *mm, unsigned long address,
 		unsigned int gup_flags, struct vm_area_struct **vma,
 		struct page **page)
-- 
2.7.4

[PATCH v2 3/9] mm/hugetlb: export hugetlb_entry_migration helper

[Aneesh Kumar K.V]

We will be using this later from the ppc64 code. Change the return type to bool.

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/hugetlb.h | 1 +
 mm/hugetlb.c            | 8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index b857fc8cc2ec..fddf6cf403d5 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -126,6 +126,7 @@ int pud_huge(pud_t pud);
 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 		unsigned long address, unsigned long end, pgprot_t newprot);
 
+bool is_hugetlb_entry_migration(pte_t pte);
 #else /* !CONFIG_HUGETLB_PAGE */
 
 static inline void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ce090186b992..25e2ee888a90 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3182,17 +3182,17 @@ static void set_huge_ptep_writable(struct vm_area_struct *vma,
 		update_mmu_cache(vma, address, ptep);
 }
 
-static int is_hugetlb_entry_migration(pte_t pte)
+bool is_hugetlb_entry_migration(pte_t pte)
 {
 	swp_entry_t swp;
 
 	if (huge_pte_none(pte) || pte_present(pte))
-		return 0;
+		return false;
 	swp = pte_to_swp_entry(pte);
 	if (non_swap_entry(swp) && is_migration_entry(swp))
-		return 1;
+		return true;
 	else
-		return 0;
+		return false;
 }
 
 static int is_hugetlb_entry_hwpoisoned(pte_t pte)
-- 
2.7.4

[PATCH v2 4/9] mm/follow_page_mask: Add support for hugetlb pgd entries.

[Aneesh Kumar K.V]

From: Anshuman Khandual <khandual@linux.vnet.ibm.com>

ppc64 supports pgd hugetlb entries. Add code to handle hugetlb pgd entries to
follow_page_mask so that ppc64 can switch to it to handle hugetlbe entries.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/hugetlb.h | 4 ++++
 mm/gup.c                | 7 +++++++
 mm/hugetlb.c            | 9 +++++++++
 3 files changed, 20 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index fddf6cf403d5..edab98f0a7b8 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -121,6 +121,9 @@ struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 				pmd_t *pmd, int flags);
 struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address,
 				pud_t *pud, int flags);
+struct page *follow_huge_pgd(struct mm_struct *mm, unsigned long address,
+			     pgd_t *pgd, int flags);
+
 int pmd_huge(pmd_t pmd);
 int pud_huge(pud_t pud);
 unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
@@ -150,6 +153,7 @@ static inline void hugetlb_show_meminfo(void)
 }
 #define follow_huge_pmd(mm, addr, pmd, flags)	NULL
 #define follow_huge_pud(mm, addr, pud, flags)	NULL
+#define follow_huge_pgd(mm, addr, pgd, flags)	NULL
 #define prepare_hugepage_range(file, addr, len)	(-EINVAL)
 #define pmd_huge(x)	0
 #define pud_huge(x)	0
diff --git a/mm/gup.c b/mm/gup.c
index 73d46f9f7b81..65255389620a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -357,6 +357,13 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
 		return no_page_table(vma, flags);
 
+	if (pgd_huge(*pgd)) {
+		page = follow_huge_pgd(mm, address, pgd, flags);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
+
 	return follow_p4d_mask(vma, address, pgd, flags, page_mask);
 }
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 25e2ee888a90..a12d3cab04fe 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4687,6 +4687,15 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
 	return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
 }
 
+struct page * __weak
+follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags)
+{
+	if (flags & FOLL_GET)
+		return NULL;
+
+	return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT);
+}
+
 #ifdef CONFIG_MEMORY_FAILURE
 
 /*
-- 
2.7.4

[PATCH v2 5/9] mm/hugetlb: Move default definition of hugepd_t earlier in the header

[Aneesh Kumar K.V]

This enable to use the hugepd_t type early. No functional change in this patch.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/hugetlb.h | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index edab98f0a7b8..f66c1d4e0d1f 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -14,6 +14,30 @@ struct ctl_table;
 struct user_struct;
 struct mmu_gather;
 
+#ifndef is_hugepd
+/*
+ * Some architectures requires a hugepage directory format that is
+ * required to support multiple hugepage sizes. For example
+ * a4fe3ce76 "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
+ * introduced the same on powerpc. This allows for a more flexible hugepage
+ * pagetable layout.
+ */
+typedef struct { unsigned long pd; } hugepd_t;
+#define is_hugepd(hugepd) (0)
+#define __hugepd(x) ((hugepd_t) { (x) })
+static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+			      unsigned pdshift, unsigned long end,
+			      int write, struct page **pages, int *nr)
+{
+	return 0;
+}
+#else
+extern int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
+		       unsigned pdshift, unsigned long end,
+		       int write, struct page **pages, int *nr);
+#endif
+
+
 #ifdef CONFIG_HUGETLB_PAGE
 
 #include <linux/mempolicy.h>
@@ -222,29 +246,6 @@ static inline int pud_write(pud_t pud)
 }
 #endif
 
-#ifndef is_hugepd
-/*
- * Some architectures requires a hugepage directory format that is
- * required to support multiple hugepage sizes. For example
- * a4fe3ce76 "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
- * introduced the same on powerpc. This allows for a more flexible hugepage
- * pagetable layout.
- */
-typedef struct { unsigned long pd; } hugepd_t;
-#define is_hugepd(hugepd) (0)
-#define __hugepd(x) ((hugepd_t) { (x) })
-static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-			      unsigned pdshift, unsigned long end,
-			      int write, struct page **pages, int *nr)
-{
-	return 0;
-}
-#else
-extern int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
-		       unsigned pdshift, unsigned long end,
-		       int write, struct page **pages, int *nr);
-#endif
-
 #define HUGETLB_ANON_FILE "anon_hugepage"
 
 enum {
-- 
2.7.4

[PATCH v2 6/9] mm/follow_page_mask: Add support for hugepage directory entry

[Aneesh Kumar K.V]

Architectures like ppc64 supports hugepage size that is not mapped to any of
of the page table levels. Instead they add an alternate page table entry format
called hugepage directory (hugepd). hugepd indicates that the page table entry maps
to a set of hugetlb pages. Add support for this in generic follow_page_mask
code. We already support this format in the generic gup code.

The defaul implementation prints warning and returns NULL. We will add ppc64
support in later patches

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/hugetlb.h |  4 ++++
 mm/gup.c                | 33 +++++++++++++++++++++++++++++++++
 mm/hugetlb.c            |  8 ++++++++
 3 files changed, 45 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index f66c1d4e0d1f..caee7c4664c8 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -141,6 +141,9 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr);
 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep);
 struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
 			      int write);
+struct page *follow_huge_pd(struct vm_area_struct *vma,
+			    unsigned long address, hugepd_t hpd,
+			    int flags, int pdshift);
 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 				pmd_t *pmd, int flags);
 struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address,
@@ -175,6 +178,7 @@ static inline void hugetlb_report_meminfo(struct seq_file *m)
 static inline void hugetlb_show_meminfo(void)
 {
 }
+#define follow_huge_pd(vma, addr, hpd, flags, pdshift) NULL
 #define follow_huge_pmd(mm, addr, pmd, flags)	NULL
 #define follow_huge_pud(mm, addr, pud, flags)	NULL
 #define follow_huge_pgd(mm, addr, pgd, flags)	NULL
diff --git a/mm/gup.c b/mm/gup.c
index 65255389620a..a7f5b82e15f3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -226,6 +226,14 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
 			return page;
 		return no_page_table(vma, flags);
 	}
+	if (is_hugepd(__hugepd(pmd_val(*pmd)))) {
+		page = follow_huge_pd(vma, address,
+				      __hugepd(pmd_val(*pmd)), flags,
+				      PMD_SHIFT);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
 	if (pmd_devmap(*pmd)) {
 		ptl = pmd_lock(mm, pmd);
 		page = follow_devmap_pmd(vma, address, pmd, flags);
@@ -292,6 +300,14 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
 			return page;
 		return no_page_table(vma, flags);
 	}
+	if (is_hugepd(__hugepd(pud_val(*pud)))) {
+		page = follow_huge_pd(vma, address,
+				      __hugepd(pud_val(*pud)), flags,
+				      PUD_SHIFT);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
 	if (pud_devmap(*pud)) {
 		ptl = pud_lock(mm, pud);
 		page = follow_devmap_pud(vma, address, pud, flags);
@@ -311,6 +327,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
 				    unsigned int flags, unsigned int *page_mask)
 {
 	p4d_t *p4d;
+	struct page *page;
 
 	p4d = p4d_offset(pgdp, address);
 	if (p4d_none(*p4d))
@@ -319,6 +336,14 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
 	if (unlikely(p4d_bad(*p4d)))
 		return no_page_table(vma, flags);
 
+	if (is_hugepd(__hugepd(p4d_val(*p4d)))) {
+		page = follow_huge_pd(vma, address,
+				      __hugepd(p4d_val(*p4d)), flags,
+				      P4D_SHIFT);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
 	return follow_pud_mask(vma, address, p4d, flags, page_mask);
 }
 
@@ -363,6 +388,14 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 			return page;
 		return no_page_table(vma, flags);
 	}
+	if (is_hugepd(__hugepd(pgd_val(*pgd)))) {
+		page = follow_huge_pd(vma, address,
+				      __hugepd(pgd_val(*pgd)), flags,
+				      PGDIR_SHIFT);
+		if (page)
+			return page;
+		return no_page_table(vma, flags);
+	}
 
 	return follow_p4d_mask(vma, address, pgd, flags, page_mask);
 }
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a12d3cab04fe..58307d62ac37 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4643,6 +4643,14 @@ follow_huge_addr(struct mm_struct *mm, unsigned long address,
 }
 
 struct page * __weak
+follow_huge_pd(struct vm_area_struct *vma,
+	       unsigned long address, hugepd_t hpd, int flags, int pdshift)
+{
+	WARN(1, "hugepd follow called with no support for hugepage directory format\n");
+	return NULL;
+}
+
+struct page * __weak
 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 		pmd_t *pmd, int flags)
 {
-- 
2.7.4

[PATCH v2 7/9] powerpc/hugetlb: Add follow_huge_pd implementation for ppc64.

[Aneesh Kumar K.V]

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/mm/hugetlbpage.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 80f6d2ed551a..5c829a83a4cc 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -17,6 +17,8 @@
 #include <linux/memblock.h>
 #include <linux/bootmem.h>
 #include <linux/moduleparam.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/tlb.h>
@@ -618,6 +620,46 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 }
 
 /*
+ * 64 bit book3s use generic follow_page_mask
+ */
+#ifdef CONFIG_PPC_BOOK3S_64
+
+struct page *follow_huge_pd(struct vm_area_struct *vma,
+			    unsigned long address, hugepd_t hpd,
+			    int flags, int pdshift)
+{
+	pte_t *ptep;
+	spinlock_t *ptl;
+	struct page *page = NULL;
+	unsigned long mask;
+	int shift = hugepd_shift(hpd);
+	struct mm_struct *mm = vma->vm_mm;
+
+retry:
+	ptl = &mm->page_table_lock;
+	spin_lock(ptl);
+
+	ptep = hugepte_offset(hpd, address, pdshift);
+	if (pte_present(*ptep)) {
+		mask = (1UL << shift) - 1;
+		page = pte_page(*ptep);
+		page += ((address & mask) >> PAGE_SHIFT);
+		if (flags & FOLL_GET)
+			get_page(page);
+	} else {
+		if (is_hugetlb_entry_migration(*ptep)) {
+			spin_unlock(ptl);
+			__migration_entry_wait(mm, ptep, ptl);
+			goto retry;
+		}
+	}
+	spin_unlock(ptl);
+	return page;
+}
+
+#else /* !CONFIG_PPC_BOOK3S_64 */
+
+/*
  * We are holding mmap_sem, so a parallel huge page collapse cannot run.
  * To prevent hugepage split, disable irq.
  */
@@ -672,6 +714,7 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
 	BUG();
 	return NULL;
 }
+#endif
 
 static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 				      unsigned long sz)
-- 
2.7.4

[PATCH v2 8/9] powerpc/mm/hugetlb: Remove follow_huge_addr for powerpc

[Aneesh Kumar K.V]

With generic code now handling hugetlb entries at pgd level and also
supporting hugepage directory format, we can now remove the powerpc
sepcific follow_huge_addr implementation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/mm/hugetlbpage.c | 64 -------------------------------------------
 1 file changed, 64 deletions(-)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 5c829a83a4cc..1816b965a142 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -619,11 +619,6 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 	} while (addr = next, addr != end);
 }
 
-/*
- * 64 bit book3s use generic follow_page_mask
- */
-#ifdef CONFIG_PPC_BOOK3S_64
-
 struct page *follow_huge_pd(struct vm_area_struct *vma,
 			    unsigned long address, hugepd_t hpd,
 			    int flags, int pdshift)
@@ -657,65 +652,6 @@ struct page *follow_huge_pd(struct vm_area_struct *vma,
 	return page;
 }
 
-#else /* !CONFIG_PPC_BOOK3S_64 */
-
-/*
- * We are holding mmap_sem, so a parallel huge page collapse cannot run.
- * To prevent hugepage split, disable irq.
- */
-struct page *
-follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
-{
-	bool is_thp;
-	pte_t *ptep, pte;
-	unsigned shift;
-	unsigned long mask, flags;
-	struct page *page = ERR_PTR(-EINVAL);
-
-	local_irq_save(flags);
-	ptep = find_linux_pte_or_hugepte(mm->pgd, address, &is_thp, &shift);
-	if (!ptep)
-		goto no_page;
-	pte = READ_ONCE(*ptep);
-	/*
-	 * Verify it is a huge page else bail.
-	 * Transparent hugepages are handled by generic code. We can skip them
-	 * here.
-	 */
-	if (!shift || is_thp)
-		goto no_page;
-
-	if (!pte_present(pte)) {
-		page = NULL;
-		goto no_page;
-	}
-	mask = (1UL << shift) - 1;
-	page = pte_page(pte);
-	if (page)
-		page += (address & mask) / PAGE_SIZE;
-
-no_page:
-	local_irq_restore(flags);
-	return page;
-}
-
-struct page *
-follow_huge_pmd(struct mm_struct *mm, unsigned long address,
-		pmd_t *pmd, int write)
-{
-	BUG();
-	return NULL;
-}
-
-struct page *
-follow_huge_pud(struct mm_struct *mm, unsigned long address,
-		pud_t *pud, int write)
-{
-	BUG();
-	return NULL;
-}
-#endif
-
 static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 				      unsigned long sz)
 {
-- 
2.7.4

[PATCH v2 9/9] powerpc/hugetlb: Enable hugetlb migration for ppc64

[Aneesh Kumar K.V]

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/Kconfig.cputype | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 80175000042d..8acc4f27d101 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -351,6 +351,11 @@ config PPC_RADIX_MMU
 	  is only implemented by IBM Power9 CPUs, if you don't have one of them
 	  you can probably disable this.
 
+config ARCH_ENABLE_HUGEPAGE_MIGRATION
+	def_bool y
+	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
+
+
 config PPC_MMU_NOHASH
 	def_bool y
 	depends on !PPC_STD_MMU
-- 
2.7.4

Re: [PATCH v2 9/9] powerpc/hugetlb: Enable hugetlb migration for ppc64

[Christophe LEROY]

Le 16/05/2017 à 11:23, Aneesh Kumar K.V a écrit :
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>   arch/powerpc/platforms/Kconfig.cputype | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 80175000042d..8acc4f27d101 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -351,6 +351,11 @@ config PPC_RADIX_MMU
>   	  is only implemented by IBM Power9 CPUs, if you don't have one of them
>   	  you can probably disable this.
>   
> +config ARCH_ENABLE_HUGEPAGE_MIGRATION
> +	def_bool y
> +	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
> +
> +

Is there a reason why you redefine ARCH_ENABLE_HUGEPAGE_MIGRATION 
instead of doing a 'select' as it is already defined in mm/Kconfig ?

Christophe

>   config PPC_MMU_NOHASH
>   	def_bool y
>   	depends on !PPC_STD_MMU
> 

Re: [PATCH v2 9/9] powerpc/hugetlb: Enable hugetlb migration for ppc64

[Aneesh Kumar K.V]

Christophe LEROY <christophe.leroy@c-s.fr> writes:

> Le 16/05/2017 à 11:23, Aneesh Kumar K.V a écrit :
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>>   arch/powerpc/platforms/Kconfig.cputype | 5 +++++
>>   1 file changed, 5 insertions(+)
>> 
>> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
>> index 80175000042d..8acc4f27d101 100644
>> --- a/arch/powerpc/platforms/Kconfig.cputype
>> +++ b/arch/powerpc/platforms/Kconfig.cputype
>> @@ -351,6 +351,11 @@ config PPC_RADIX_MMU
>>   	  is only implemented by IBM Power9 CPUs, if you don't have one of them
>>   	  you can probably disable this.
>>   
>> +config ARCH_ENABLE_HUGEPAGE_MIGRATION
>> +	def_bool y
>> +	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
>> +
>> +
>
> Is there a reason why you redefine ARCH_ENABLE_HUGEPAGE_MIGRATION 
> instead of doing a 'select' as it is already defined in mm/Kconfig ?
>

That got copied from x86 Kconfig i guess.

-aneesh