[PATCH V5 2/3] mm: Update generic gup implementation to handle hugepage directory
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Thu Nov 6 03:27:40 AEDT 2014
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.
Tested-by: Steve Capper <steve.capper at linaro.org>
Acked-by: Steve Capper <steve.capper at linaro.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
Changes from V4:
* Add pmd accessor needed for the change to ppc64
* Drop the assumption that we can access pmd using pte_* functions.
arch/powerpc/include/asm/page.h | 1 +
include/linux/hugetlb.h | 46 +++++++++++++++++++++++
mm/gup.c | 81 +++++++++++++++++++++++++++++++++++++----
3 files changed, 120 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 26fe1ae15212..f973fce73a43 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 6e6d338641fe..e6b62f30ab21 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -175,6 +175,52 @@ 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 pgd_write
+static inline int pgd_write(pgd_t pgd)
+{
+ BUG();
+ return 0;
+}
+#endif
+
+#ifndef pud_write
+static inline int pud_write(pud_t pud)
+{
+ BUG();
+ return 0;
+}
+#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"
diff --git a/mm/gup.c b/mm/gup.c
index cd62c8c90d4a..0ca1df9075ab 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3,7 +3,6 @@
#include <linux/err.h>
#include <linux/spinlock.h>
-#include <linux/hugetlb.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
@@ -12,6 +11,7 @@
#include <linux/sched.h>
#include <linux/rwsem.h>
+#include <linux/hugetlb.h>
#include <asm/pgtable.h>
#include "internal.h"
@@ -875,6 +875,49 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
return 1;
}
+static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
+ unsigned long end, int write,
+ struct page **pages, int *nr)
+{
+ int refs;
+ struct page *head, *page, *tail;
+
+ if (write && !pgd_write(orig))
+ return 0;
+
+ refs = 0;
+ head = pgd_page(orig);
+ page = head + ((addr & ~PGDIR_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;
+ return 0;
+ }
+
+ if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) {
+ *nr -= refs;
+ while (refs--)
+ put_page(head);
+ return 0;
+ }
+
+ while (refs--) {
+ if (PageTail(tail))
+ get_huge_page_tail(tail);
+ tail++;
+ }
+
+ return 1;
+}
+
static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
@@ -902,6 +945,14 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
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 +960,26 @@ 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,
- int write, struct page **pages, int *nr)
+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 (unlikely(pud_huge(pud))) {
if (!gup_huge_pud(pud, pudp, addr, next, write,
- pages, nr))
+ 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 +1025,20 @@ 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_pgd(pgd, pgdp, addr, 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);
--
2.1.0
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