[PATCH V3 1/2] mm: Update generic gup implementation to handle hugepage directory
From: Aneesh Kumar K.V
Date: Sat Oct 25 2014 - 17:15:17 EST
Update generic gup implementation with powerpc specific details.
On powerpc at pmd level we can have hugepte, normal pmd pointer
or a pointer to the hugepage directory.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
Changes from V3:
* Explain pgd_huge, also move the definition to linux/hugetlb.h.
Both pgd_huge and is_hugepd are related to hugepages and hugetlb.h
is the right header
arch/arm/include/asm/pgtable.h | 2 +
arch/arm64/include/asm/pgtable.h | 2 +
arch/powerpc/include/asm/page.h | 1 +
include/linux/hugetlb.h | 30 +++++++++++
include/linux/mm.h | 7 +++
mm/gup.c | 113 +++++++++++++++++++--------------------
6 files changed, 96 insertions(+), 59 deletions(-)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 3b30062..c52d261 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -181,6 +181,8 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(addr) pgd_offset(&init_mm, addr)
+#define pgd_huge(pgd) (0)
+
#define pmd_none(pmd) (!pmd_val(pmd))
#define pmd_present(pmd) (pmd_val(pmd))
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 41a43bf..f532a14 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -464,6 +464,8 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
+#define pgd_huge(pgd) (0)
+
/*
* Encode and decode a swap entry:
* bits 0-1: present (must be zero)
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 26fe1ae..f973fce 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -380,6 +380,7 @@ static inline int hugepd_ok(hugepd_t hpd)
#endif
#define is_hugepd(pdep) (hugepd_ok(*((hugepd_t *)(pdep))))
+#define pgd_huge pgd_huge
int pgd_huge(pgd_t pgd);
#else /* CONFIG_HUGETLB_PAGE */
#define is_hugepd(pdep) 0
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 6e6d338..de63dbc 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -175,6 +175,36 @@ static inline void __unmap_hugepage_range(struct mmu_gather *tlb,
}
#endif /* !CONFIG_HUGETLB_PAGE */
+/*
+ * hugepages at page global directory. If arch support
+ * hugepages at pgd level, they need to define this.
+ */
+#ifndef pgd_huge
+#define pgd_huge(x) 0
+#endif
+
+#ifndef is_hugepd
+/*
+ * Some architectures requires a hugepage directory format that is
+ * required to support multiple hugepage sizes. For example
+ * a4fe3ce7699bfe1bd88f816b55d42d8fe1dac655 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"
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 02d11ee..31d7fac 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1219,6 +1219,13 @@ long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
struct vm_area_struct **vmas);
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
+
+#ifdef CONFIG_HAVE_GENERIC_RCU_GUP
+extern int gup_huge_pte(pte_t orig, pte_t *ptep, unsigned long addr,
+ unsigned long sz, unsigned long end, int write,
+ struct page **pages, int *nr);
+#endif
+
struct kvec;
int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
struct page **pages);
diff --git a/mm/gup.c b/mm/gup.c
index cd62c8c..30773f3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -786,65 +786,31 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
}
#endif /* __HAVE_ARCH_PTE_SPECIAL */
-static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr)
+int gup_huge_pte(pte_t orig, pte_t *ptep, unsigned long addr,
+ unsigned long sz, unsigned long end, int write,
+ struct page **pages, int *nr)
{
- struct page *head, *page, *tail;
int refs;
+ unsigned long pte_end;
+ struct page *head, *page, *tail;
- if (write && !pmd_write(orig))
- return 0;
-
- refs = 0;
- head = pmd_page(orig);
- page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
- tail = page;
- do {
- VM_BUG_ON_PAGE(compound_head(page) != head, page);
- pages[*nr] = page;
- (*nr)++;
- page++;
- refs++;
- } while (addr += PAGE_SIZE, addr != end);
- if (!page_cache_add_speculative(head, refs)) {
- *nr -= refs;
+ if (write && !pte_write(orig))
return 0;
- }
- if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
- *nr -= refs;
- while (refs--)
- put_page(head);
+ if (!pte_present(orig))
return 0;
- }
- /*
- * Any tail pages need their mapcount reference taken before we
- * return. (This allows the THP code to bump their ref count when
- * they are split into base pages).
- */
- while (refs--) {
- if (PageTail(tail))
- get_huge_page_tail(tail);
- tail++;
- }
-
- return 1;
-}
-
-static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
- unsigned long end, int write, struct page **pages, int *nr)
-{
- struct page *head, *page, *tail;
- int refs;
+ pte_end = (addr + sz) & ~(sz-1);
+ if (pte_end < end)
+ end = pte_end;
- if (write && !pud_write(orig))
- return 0;
+ /* hugepages are never "special" */
+ VM_BUG_ON(!pfn_valid(pte_pfn(orig)));
refs = 0;
- head = pud_page(orig);
- page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+ head = pte_page(orig);
+ page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
tail = page;
do {
VM_BUG_ON_PAGE(compound_head(page) != head, page);
@@ -859,13 +825,18 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
return 0;
}
- if (unlikely(pud_val(orig) != pud_val(*pudp))) {
+ if (unlikely(pte_val(orig) != pte_val(*ptep))) {
*nr -= refs;
while (refs--)
put_page(head);
return 0;
}
+ /*
+ * Any tail pages need their mapcount reference taken before we
+ * return. (This allows the THP code to bump their ref count when
+ * they are split into base pages).
+ */
while (refs--) {
if (PageTail(tail))
get_huge_page_tail(tail);
@@ -898,10 +869,19 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
if (pmd_numa(pmd))
return 0;
- if (!gup_huge_pmd(pmd, pmdp, addr, next, write,
- pages, nr))
+ if (!gup_huge_pte(__pte(pmd_val(pmd)), (pte_t *)pmdp,
+ addr, PMD_SIZE, next,
+ write, pages, nr))
return 0;
+ } else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) {
+ /*
+ * architecture have different format for hugetlbfs
+ * pmd format and THP pmd format
+ */
+ if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
+ PMD_SHIFT, next, write, pages, nr))
+ return 0;
} else if (!gup_pte_range(pmd, addr, next, write, pages, nr))
return 0;
} while (pmdp++, addr = next, addr != end);
@@ -909,22 +889,27 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
return 1;
}
-static int gup_pud_range(pgd_t *pgdp, unsigned long addr, unsigned long end,
+static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
unsigned long next;
pud_t *pudp;
- pudp = pud_offset(pgdp, addr);
+ pudp = pud_offset(&pgd, addr);
do {
pud_t pud = ACCESS_ONCE(*pudp);
next = pud_addr_end(addr, end);
if (pud_none(pud))
return 0;
- if (pud_huge(pud)) {
- if (!gup_huge_pud(pud, pudp, addr, next, write,
- pages, nr))
+ if (unlikely(pud_huge(pud))) {
+ if (!gup_huge_pte(__pte(pud_val(pud)), (pte_t *)pudp,
+ addr, PUD_SIZE, next,
+ write, pages, nr))
+ return 0;
+ } else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
+ if (!gup_huge_pd(__hugepd(pud_val(pud)), addr,
+ PUD_SHIFT, next, write, pages, nr))
return 0;
} else if (!gup_pmd_range(pud, addr, next, write, pages, nr))
return 0;
@@ -970,10 +955,21 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
local_irq_save(flags);
pgdp = pgd_offset(mm, addr);
do {
+ pgd_t pgd = ACCESS_ONCE(*pgdp);
+
next = pgd_addr_end(addr, end);
- if (pgd_none(*pgdp))
+ if (pgd_none(pgd))
break;
- else if (!gup_pud_range(pgdp, addr, next, write, pages, &nr))
+ if (unlikely(pgd_huge(pgd))) {
+ if (!gup_huge_pte(__pte(pgd_val(pgd)), (pte_t *)pgdp,
+ addr, PGDIR_SIZE, next,
+ write, pages, &nr))
+ break;
+ } else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) {
+ if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr,
+ PGDIR_SHIFT, next, write, pages, &nr))
+ break;
+ } else if (!gup_pud_range(pgd, addr, next, write, pages, &nr))
break;
} while (pgdp++, addr = next, addr != end);
local_irq_restore(flags);
@@ -1028,5 +1024,4 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
return ret;
}
-
#endif /* CONFIG_HAVE_GENERIC_RCU_GUP */
--
2.1.0
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