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Groups > linux.kernel > #1649532 > unrolled thread

[PATCH v4 0/8] Support for contiguous pte hugepages

Started byPunit Agrawal <punit.agrawal@arm.com>
First post2017-05-24 14:00 +0200
Last post2017-06-05 15:00 +0200
Articles 6 — 1 participant

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Contents

  [PATCH v4 0/8] Support for contiguous pte hugepages Punit Agrawal <punit.agrawal@arm.com> - 2017-05-24 14:00 +0200
    [PATCH v4 5/8] mm/hugetlb: add size parameter to huge_pte_offset() Punit Agrawal <punit.agrawal@arm.com> - 2017-05-24 14:00 +0200
    [PATCH v4 1/8] arm64: hugetlb: Refactor find_num_contig Punit Agrawal <punit.agrawal@arm.com> - 2017-05-24 14:00 +0200
    [PATCH v4 6/8] mm/hugetlb: Allow architectures to override huge_pte_clear() Punit Agrawal <punit.agrawal@arm.com> - 2017-05-24 14:00 +0200
    [PATCH v4 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages Punit Agrawal <punit.agrawal@arm.com> - 2017-05-24 14:00 +0200
      [PATCH v4.1 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages Punit Agrawal <punit.agrawal@arm.com> - 2017-06-05 15:00 +0200

#1649532 — [PATCH v4 0/8] Support for contiguous pte hugepages

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-05-24 14:00 +0200
Subject[PATCH v4 0/8] Support for contiguous pte hugepages
Message-ID<tKD7j-1Uh-9@gated-at.bofh.it>
Hi,

This patchset updates the hugetlb code to fix issues arising from
contiguous pte hugepages (such as on arm64). Compared to v3, This
version addresses a build failure on arm64 by including two cleanup
patches. Other than the arm64 cleanups, the rest are generic code
changes. The remaining arm64 support based on these patches will be
posted separately. The patches are based on v4.12-rc2. Previous
related postings can be found at [0], [1], [2], and [3].

The patches fall into three categories -

* Patch 1-2 - arm64 cleanups required to greatly simplify changing
  huge_pte_offset() prototype in Patch 5.

  Catalin, Will - are you happy for these patches to go via mm?

* Patches 3-4 address issues with gup

* Patches 5-8 relate to passing a size argument to hugepage helpers to
  disambiguate the size of the referred page. These changes are
  required to enable arch code to properly handle swap entries for
  contiguous pte hugepages.

  The changes to huge_pte_offset() (patch 5) touch multiple
  architectures but I've managed to minimise these changes for the
  other affected functions - huge_pte_clear() and set_huge_pte_at().

These patches gate the enabling of contiguous hugepages support on
arm64 which has been requested for systems using !4k page granule.

Feedback welcome.

Thanks,
Punit

v3 -> v4

* Reworked huge_pte_clear() and set_huge_swap_pte_at() to use #ifndef
  block pattern
* Included two arm64 hugetlb patches to address build failure
* Updated tags

v2 -> v3

* Added gup fixes

v1 -> v2

* switch huge_pte_offset() to use size instead of hstate for
  consistency with the rest of the api
* Expand the series to address huge_pte_clear() and set_huge_pte_at()

RFC -> v1

* Fixed a missing conversion of huge_pte_offset() prototype to add
  hstate parameter. Reported by 0-day.

[0] https://www.spinics.net/lists/arm-kernel/msg582682.html
[1] http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1370686.html
[2] https://lkml.org/lkml/2017/3/30/770
[3] https://lkml.org/lkml/2017/3/23/293


Punit Agrawal (5):
  mm, gup: Ensure real head page is ref-counted when using hugepages
  mm/hugetlb: add size parameter to huge_pte_offset()
  mm/hugetlb: Allow architectures to override huge_pte_clear()
  mm/hugetlb: Introduce set_huge_swap_pte_at() helper
  mm: rmap: Use correct helper when poisoning hugepages

Steve Capper (2):
  arm64: hugetlb: Refactor find_num_contig
  arm64: hugetlb: Remove spurious calls to huge_ptep_offset

Will Deacon (1):
  mm, gup: Remove broken VM_BUG_ON_PAGE compound check for hugepages

 arch/arm64/mm/hugetlbpage.c     | 53 +++++++++++++++++------------------------
 arch/ia64/mm/hugetlbpage.c      |  4 ++--
 arch/metag/mm/hugetlbpage.c     |  3 ++-
 arch/mips/mm/hugetlbpage.c      |  3 ++-
 arch/parisc/mm/hugetlbpage.c    |  3 ++-
 arch/powerpc/mm/hugetlbpage.c   |  2 +-
 arch/s390/include/asm/hugetlb.h |  2 +-
 arch/s390/mm/hugetlbpage.c      |  3 ++-
 arch/sh/mm/hugetlbpage.c        |  3 ++-
 arch/sparc/mm/hugetlbpage.c     |  3 ++-
 arch/tile/mm/hugetlbpage.c      |  3 ++-
 arch/x86/mm/hugetlbpage.c       |  2 +-
 fs/userfaultfd.c                |  7 ++++--
 include/asm-generic/hugetlb.h   |  4 +++-
 include/linux/hugetlb.h         | 13 ++++++++--
 mm/gup.c                        | 15 +++++-------
 mm/hugetlb.c                    | 33 +++++++++++++++----------
 mm/page_vma_mapped.c            |  3 ++-
 mm/pagewalk.c                   |  3 ++-
 mm/rmap.c                       |  7 ++++--
 20 files changed, 95 insertions(+), 74 deletions(-)

-- 
2.11.0

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#1649534 — [PATCH v4 5/8] mm/hugetlb: add size parameter to huge_pte_offset()

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-05-24 14:00 +0200
Subject[PATCH v4 5/8] mm/hugetlb: add size parameter to huge_pte_offset()
Message-ID<tKD7k-1Uh-25@gated-at.bofh.it>
In reply to#1649532
A poisoned or migrated hugepage is stored as a swap entry in the page
tables. On architectures that support hugepages consisting of contiguous
page table entries (such as on arm64) this leads to ambiguity in
determining the page table entry to return in huge_pte_offset() when a
poisoned entry is encountered.

Let's remove the ambiguity by adding a size parameter to convey
additional information about the requested address. Also fixup the
definition/usage of huge_pte_offset() throughout the tree.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: James Hogan <james.hogan@imgtec.com> (odd fixer:METAG ARCHITECTURE)
Cc: Ralf Baechle <ralf@linux-mips.org> (supporter:MIPS)
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
---
 arch/arm64/mm/hugetlbpage.c   |  3 ++-
 arch/ia64/mm/hugetlbpage.c    |  4 ++--
 arch/metag/mm/hugetlbpage.c   |  3 ++-
 arch/mips/mm/hugetlbpage.c    |  3 ++-
 arch/parisc/mm/hugetlbpage.c  |  3 ++-
 arch/powerpc/mm/hugetlbpage.c |  2 +-
 arch/s390/mm/hugetlbpage.c    |  3 ++-
 arch/sh/mm/hugetlbpage.c      |  3 ++-
 arch/sparc/mm/hugetlbpage.c   |  3 ++-
 arch/tile/mm/hugetlbpage.c    |  3 ++-
 arch/x86/mm/hugetlbpage.c     |  2 +-
 fs/userfaultfd.c              |  7 +++++--
 include/linux/hugetlb.h       |  5 +++--
 mm/hugetlb.c                  | 23 ++++++++++++++---------
 mm/page_vma_mapped.c          |  3 ++-
 mm/pagewalk.c                 |  3 ++-
 16 files changed, 46 insertions(+), 27 deletions(-)

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index f89aa8fa5855..656e0ece2289 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -131,7 +131,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index 85de86d36fdf..ae35140332f7 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -44,7 +44,7 @@ huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 }
 
 pte_t *
-huge_pte_offset (struct mm_struct *mm, unsigned long addr)
+huge_pte_offset (struct mm_struct *mm, unsigned long addr, unsigned long sz)
 {
 	unsigned long taddr = htlbpage_to_page(addr);
 	pgd_t *pgd;
@@ -92,7 +92,7 @@ struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int writ
 	if (REGION_NUMBER(addr) != RGN_HPAGE)
 		return ERR_PTR(-EINVAL);
 
-	ptep = huge_pte_offset(mm, addr);
+	ptep = huge_pte_offset(mm, addr, HPAGE_SIZE);
 	if (!ptep || pte_none(*ptep))
 		return NULL;
 	page = pte_page(*ptep);
diff --git a/arch/metag/mm/hugetlbpage.c b/arch/metag/mm/hugetlbpage.c
index db1b7da91e4f..67fd53e2935a 100644
--- a/arch/metag/mm/hugetlbpage.c
+++ b/arch/metag/mm/hugetlbpage.c
@@ -74,7 +74,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/mips/mm/hugetlbpage.c b/arch/mips/mm/hugetlbpage.c
index 74aa6f62468f..cef152234312 100644
--- a/arch/mips/mm/hugetlbpage.c
+++ b/arch/mips/mm/hugetlbpage.c
@@ -36,7 +36,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
+		       unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/parisc/mm/hugetlbpage.c b/arch/parisc/mm/hugetlbpage.c
index aa50ac090e9b..5eb8f633b282 100644
--- a/arch/parisc/mm/hugetlbpage.c
+++ b/arch/parisc/mm/hugetlbpage.c
@@ -69,7 +69,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index a4f33de4008e..e46744d3b4ae 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -55,7 +55,7 @@ static unsigned nr_gpages;
 
 #define hugepd_none(hpd)	(hpd_val(hpd) == 0)
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 {
 	/* Only called for hugetlbfs pages, hence can ignore THP */
 	return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL, NULL);
diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
index 9b4050caa4e9..ae23afc18493 100644
--- a/arch/s390/mm/hugetlbpage.c
+++ b/arch/s390/mm/hugetlbpage.c
@@ -176,7 +176,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return (pte_t *) pmdp;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgdp;
 	pud_t *pudp;
diff --git a/arch/sh/mm/hugetlbpage.c b/arch/sh/mm/hugetlbpage.c
index cc948db74878..d2412d2d6462 100644
--- a/arch/sh/mm/hugetlbpage.c
+++ b/arch/sh/mm/hugetlbpage.c
@@ -42,7 +42,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index 7c29d38e6b99..8989c5e155b3 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -277,7 +277,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
index cb10153b5c9f..1f0993945521 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -102,7 +102,8 @@ static pte_t *get_pte(pte_t *base, int index, int level)
 	return ptep;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	pud_t *pud;
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 302f43fd9c28..ccf509063dfd 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -33,7 +33,7 @@ follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 	if (!vma || !is_vm_hugetlb_page(vma))
 		return ERR_PTR(-EINVAL);
 
-	pte = huge_pte_offset(mm, address);
+	pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
 
 	/* hugetlb should be locked, and hence, prefaulted */
 	WARN_ON(!pte || pte_none(*pte));
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index f7555fc25877..7b9c94837895 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -214,6 +214,7 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
  * hugepmd ranges.
  */
 static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+					 struct vm_area_struct *vma,
 					 unsigned long address,
 					 unsigned long flags,
 					 unsigned long reason)
@@ -224,7 +225,7 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 
 	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
 
-	pte = huge_pte_offset(mm, address);
+	pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
 	if (!pte)
 		goto out;
 
@@ -243,6 +244,7 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 }
 #else
 static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+					 struct vm_area_struct *vma,
 					 unsigned long address,
 					 unsigned long flags,
 					 unsigned long reason)
@@ -435,7 +437,8 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 		must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
 						  reason);
 	else
-		must_wait = userfaultfd_huge_must_wait(ctx, vmf->address,
+		must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma,
+						       vmf->address,
 						       vmf->flags, reason);
 	up_read(&mm->mmap_sem);
 
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index b857fc8cc2ec..23010a3b2047 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -113,7 +113,8 @@ extern struct list_head huge_boot_pages;
 
 pte_t *huge_pte_alloc(struct mm_struct *mm,
 			unsigned long addr, unsigned long sz);
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr);
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz);
 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);
@@ -157,7 +158,7 @@ static inline void hugetlb_show_meminfo(void)
 #define hugetlb_fault(mm, vma, addr, flags)	({ BUG(); 0; })
 #define hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
 				src_addr, pagep)	({ BUG(); 0; })
-#define huge_pte_offset(mm, address)	0
+#define huge_pte_offset(mm, address, sz)	0
 static inline int dequeue_hwpoisoned_huge_page(struct page *page)
 {
 	return 0;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e5828875f7bb..0e4d1fb3122f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3233,7 +3233,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 
 	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
 		spinlock_t *src_ptl, *dst_ptl;
-		src_pte = huge_pte_offset(src, addr);
+		src_pte = huge_pte_offset(src, addr, sz);
 		if (!src_pte)
 			continue;
 		dst_pte = huge_pte_alloc(dst, addr, sz);
@@ -3317,7 +3317,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 	address = start;
 	for (; address < end; address += sz) {
-		ptep = huge_pte_offset(mm, address);
+		ptep = huge_pte_offset(mm, address, sz);
 		if (!ptep)
 			continue;
 
@@ -3535,7 +3535,8 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 			unmap_ref_private(mm, vma, old_page, address);
 			BUG_ON(huge_pte_none(pte));
 			spin_lock(ptl);
-			ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+			ptep = huge_pte_offset(mm, address & huge_page_mask(h),
+					       huge_page_size(h));
 			if (likely(ptep &&
 				   pte_same(huge_ptep_get(ptep), pte)))
 				goto retry_avoidcopy;
@@ -3574,7 +3575,8 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * before the page tables are altered
 	 */
 	spin_lock(ptl);
-	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+	ptep = huge_pte_offset(mm, address & huge_page_mask(h),
+			       huge_page_size(h));
 	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
 		ClearPagePrivate(new_page);
 
@@ -3861,7 +3863,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	address &= huge_page_mask(h);
 
-	ptep = huge_pte_offset(mm, address);
+	ptep = huge_pte_offset(mm, address, huge_page_size(h));
 	if (ptep) {
 		entry = huge_ptep_get(ptep);
 		if (unlikely(is_hugetlb_entry_migration(entry))) {
@@ -4118,7 +4120,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		 *
 		 * Note that page table lock is not held when pte is null.
 		 */
-		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
+		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h),
+				      huge_page_size(h));
 		if (pte)
 			ptl = huge_pte_lock(h, mm, pte);
 		absent = !pte || huge_pte_none(huge_ptep_get(pte));
@@ -4252,7 +4255,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 	i_mmap_lock_write(vma->vm_file->f_mapping);
 	for (; address < end; address += huge_page_size(h)) {
 		spinlock_t *ptl;
-		ptep = huge_pte_offset(mm, address);
+		ptep = huge_pte_offset(mm, address, huge_page_size(h));
 		if (!ptep)
 			continue;
 		ptl = huge_pte_lock(h, mm, ptep);
@@ -4516,7 +4519,8 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
 
 		saddr = page_table_shareable(svma, vma, addr, idx);
 		if (saddr) {
-			spte = huge_pte_offset(svma->vm_mm, saddr);
+			spte = huge_pte_offset(svma->vm_mm, saddr,
+					       vma_mmu_pagesize(svma));
 			if (spte) {
 				get_page(virt_to_page(spte));
 				break;
@@ -4612,7 +4616,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 	return pte;
 }
 
-pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+pte_t *huge_pte_offset(struct mm_struct *mm,
+		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
 	p4d_t *p4d;
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index de9c40d7304a..8ec6ba230bb9 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -116,7 +116,8 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 
 	if (unlikely(PageHuge(pvmw->page))) {
 		/* when pud is not present, pte will be NULL */
-		pvmw->pte = huge_pte_offset(mm, pvmw->address);
+		pvmw->pte = huge_pte_offset(mm, pvmw->address,
+					    PAGE_SIZE << compound_order(page));
 		if (!pvmw->pte)
 			return false;
 
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 60f7856e508f..1a4197965415 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -180,12 +180,13 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 	struct hstate *h = hstate_vma(vma);
 	unsigned long next;
 	unsigned long hmask = huge_page_mask(h);
+	unsigned long sz = huge_page_size(h);
 	pte_t *pte;
 	int err = 0;
 
 	do {
 		next = hugetlb_entry_end(h, addr, end);
-		pte = huge_pte_offset(walk->mm, addr & hmask);
+		pte = huge_pte_offset(walk->mm, addr & hmask, sz);
 		if (pte && walk->hugetlb_entry)
 			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
 		if (err)
-- 
2.11.0

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#1649538 — [PATCH v4 1/8] arm64: hugetlb: Refactor find_num_contig

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-05-24 14:00 +0200
Subject[PATCH v4 1/8] arm64: hugetlb: Refactor find_num_contig
Message-ID<tKD7l-1Uh-35@gated-at.bofh.it>
In reply to#1649532
From: Steve Capper <steve.capper@arm.com>

As we regularly check for contiguous pte's in the huge accessors, remove
this extra check from find_num_contig.

Cc: David Woods <dwoods@mellanox.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>
[ Resolved rebase conflicts due to patch re-ordering ]
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
---
 arch/arm64/mm/hugetlbpage.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 69b8200b1cfd..710bf935a473 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -42,15 +42,13 @@ int pud_huge(pud_t pud)
 }
 
 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
-			   pte_t *ptep, pte_t pte, size_t *pgsize)
+			   pte_t *ptep, size_t *pgsize)
 {
 	pgd_t *pgd = pgd_offset(mm, addr);
 	pud_t *pud;
 	pmd_t *pmd;
 
 	*pgsize = PAGE_SIZE;
-	if (!pte_cont(pte))
-		return 1;
 	pud = pud_offset(pgd, addr);
 	pmd = pmd_offset(pud, addr);
 	if ((pte_t *)pmd == ptep) {
@@ -65,15 +63,16 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 {
 	size_t pgsize;
 	int i;
-	int ncontig = find_num_contig(mm, addr, ptep, pte, &pgsize);
+	int ncontig;
 	unsigned long pfn;
 	pgprot_t hugeprot;
 
-	if (ncontig == 1) {
+	if (!pte_cont(pte)) {
 		set_pte_at(mm, addr, ptep, pte);
 		return;
 	}
 
+	ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 	pfn = pte_pfn(pte);
 	hugeprot = __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
 	for (i = 0; i < ncontig; i++) {
@@ -188,7 +187,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 		bool is_dirty = false;
 
 		cpte = huge_pte_offset(mm, addr);
-		ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
+		ncontig = find_num_contig(mm, addr, cpte, &pgsize);
 		/* save the 1st pte to return */
 		pte = ptep_get_and_clear(mm, addr, cpte);
 		for (i = 1, addr += pgsize; i < ncontig; ++i, addr += pgsize) {
@@ -228,7 +227,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 		cpte = huge_pte_offset(vma->vm_mm, addr);
 		pfn = pte_pfn(*cpte);
 		ncontig = find_num_contig(vma->vm_mm, addr, cpte,
-					  *cpte, &pgsize);
+					  &pgsize);
 		for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize) {
 			changed |= ptep_set_access_flags(vma, addr, cpte,
 							pfn_pte(pfn,
@@ -251,7 +250,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		size_t pgsize = 0;
 
 		cpte = huge_pte_offset(mm, addr);
-		ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
+		ncontig = find_num_contig(mm, addr, cpte, &pgsize);
 		for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
 			ptep_set_wrprotect(mm, addr, cpte);
 	} else {
@@ -269,7 +268,7 @@ void huge_ptep_clear_flush(struct vm_area_struct *vma,
 
 		cpte = huge_pte_offset(vma->vm_mm, addr);
 		ncontig = find_num_contig(vma->vm_mm, addr, cpte,
-					  *cpte, &pgsize);
+					  &pgsize);
 		for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
 			ptep_clear_flush(vma, addr, cpte);
 	} else {
-- 
2.11.0

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#1649540 — [PATCH v4 6/8] mm/hugetlb: Allow architectures to override huge_pte_clear()

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-05-24 14:00 +0200
Subject[PATCH v4 6/8] mm/hugetlb: Allow architectures to override huge_pte_clear()
Message-ID<tKD7l-1Uh-41@gated-at.bofh.it>
In reply to#1649532
When unmapping a hugepage range, huge_pte_clear() is used to clear the
page table entries that are marked as not present. huge_pte_clear()
internally just ends up calling pte_clear() which does not correctly
deal with hugepages consisting of contiguous page table entries.

Add a size argument to address this issue and allow architectures to
override huge_pte_clear() by wrapping it in a #ifndef block.

Update s390 implementation with the size parameter as well.

Note that the change only affects huge_pte_clear() - the other generic
hugetlb functions don't need any change.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
---
 arch/s390/include/asm/hugetlb.h | 2 +-
 include/asm-generic/hugetlb.h   | 4 +++-
 mm/hugetlb.c                    | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index cd546a245c68..c0443500baec 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -39,7 +39,7 @@ static inline int prepare_hugepage_range(struct file *file,
 #define arch_clear_hugepage_flags(page)		do { } while (0)
 
 static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
-				  pte_t *ptep)
+				  pte_t *ptep, unsigned long sz)
 {
 	if ((pte_val(*ptep) & _REGION_ENTRY_TYPE_MASK) == _REGION_ENTRY_TYPE_R3)
 		pte_val(*ptep) = _REGION3_ENTRY_EMPTY;
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 99b490b4d05a..540354f94f83 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -31,10 +31,12 @@ static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
 	return pte_modify(pte, newprot);
 }
 
+#ifndef huge_pte_clear
 static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
-				  pte_t *ptep)
+		    pte_t *ptep, unsigned long sz)
 {
 	pte_clear(mm, addr, ptep);
 }
+#endif
 
 #endif /* _ASM_GENERIC_HUGETLB_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0e4d1fb3122f..ddfed20cd637 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3338,7 +3338,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		 * unmapped and its refcount is dropped, so just clear pte here.
 		 */
 		if (unlikely(!pte_present(pte))) {
-			huge_pte_clear(mm, address, ptep);
+			huge_pte_clear(mm, address, ptep, sz);
 			spin_unlock(ptl);
 			continue;
 		}
-- 
2.11.0

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#1649541 — [PATCH v4 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-05-24 14:00 +0200
Subject[PATCH v4 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages
Message-ID<tKD7l-1Uh-37@gated-at.bofh.it>
In reply to#1649532
When speculatively taking references to a hugepage using
page_cache_add_speculative() in gup_huge_pmd(), it is assumed that the
page returned by pmd_page() is the head page. Although normally true,
this assumption doesn't hold when the hugepage comprises of successive
page table entries such as when using contiguous bit on arm64 at PTE or
PMD levels.

This can be addressed by ensuring that the page passed to
page_cache_add_speculative() is the real head or by de-referencing the
head page within the function.

We take the first approach to keep the usage pattern aligned with
page_cache_get_speculative() where users already pass the appropriate
page, i.e., the de-referenced head.

Apply the same logic to fix gup_huge_[pud|pgd]() as well.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/gup.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index ccf8cb38234f..be67996513be 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1358,8 +1358,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		return __gup_device_huge_pmd(orig, addr, end, pages, nr);
 
 	refs = 0;
-	head = pmd_page(orig);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1367,6 +1366,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(page);
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
@@ -1396,8 +1396,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		return __gup_device_huge_pud(orig, addr, end, pages, nr);
 
 	refs = 0;
-	head = pud_page(orig);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+	page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1405,6 +1404,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(page);
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
@@ -1433,8 +1433,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 
 	BUILD_BUG_ON(pgd_devmap(orig));
 	refs = 0;
-	head = pgd_page(orig);
-	page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
+	page = pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1442,6 +1441,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(page);
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
-- 
2.11.0

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#1657579 — [PATCH v4.1 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages

FromPunit Agrawal <punit.agrawal@arm.com>
Date2017-06-05 15:00 +0200
Subject[PATCH v4.1 4/8] mm, gup: Ensure real head page is ref-counted when using hugepages
Message-ID<tOZLY-30O-31@gated-at.bofh.it>
In reply to#1649541
When speculatively taking references to a hugepage using
page_cache_add_speculative() in gup_huge_pmd(), it is assumed that the
page returned by pmd_page() is the head page. Although normally true,
this assumption doesn't hold when the hugepage comprises of successive
page table entries such as when using contiguous bit on arm64 at PTE or
PMD levels.

This can be addressed by ensuring that the page passed to
page_cache_add_speculative() is the real head or by de-referencing the
head page within the function.

We take the first approach to keep the usage pattern aligned with
page_cache_get_speculative() where users already pass the appropriate
page, i.e., the de-referenced head.

Apply the same logic to fix gup_huge_[pud|pgd]() as well.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---

Hi Andrew,

Please update the patch in your queue with this version.

It fixes the ltp failures reported by Yury[0]. The original patch led
to incorrect ref-count on certain pages due to taking a referencing on
the following page in some instances. Should be fixed with this
version.

Thanks,
Punit

[0] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/510318.html

 mm/gup.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index e74e0b5a0c7c..6bd39264d0e7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1354,8 +1354,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		return __gup_device_huge_pmd(orig, addr, end, pages, nr);
 
 	refs = 0;
-	head = pmd_page(orig);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1363,6 +1362,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(pmd_page(orig));
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
@@ -1392,8 +1392,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		return __gup_device_huge_pud(orig, addr, end, pages, nr);
 
 	refs = 0;
-	head = pud_page(orig);
-	page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+	page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1401,6 +1400,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(pud_page(orig));
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
@@ -1429,8 +1429,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 
 	BUILD_BUG_ON(pgd_devmap(orig));
 	refs = 0;
-	head = pgd_page(orig);
-	page = head + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
+	page = pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
 	do {
 		pages[*nr] = page;
 		(*nr)++;
@@ -1438,6 +1437,7 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 		refs++;
 	} while (addr += PAGE_SIZE, addr != end);
 
+	head = compound_head(pgd_page(orig));
 	if (!page_cache_add_speculative(head, refs)) {
 		*nr -= refs;
 		return 0;
-- 
2.11.0

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