mm/hugetlb: introduce set_huge_swap_pte_at() helper

set_huge_pte_at(), an architecture callback to populate hugepage ptes,
does not provide the range of virtual memory that is targeted.  This
leads to ambiguity when dealing with swap entries on architectures that
support hugepages consisting of contiguous ptes.

Fix the problem by introducing an overridable helper that is called when
populating the page tables with swap entries.  The size of the targeted
region is provided to the helper to help determine the number of entries
to be updated.

Provide a default implementation that maintains the current behaviour.

[punit.agrawal@arm.com: v4]
Link: http://lkml.kernel.org/r/20170524115409.31309-8-punit.agrawal@arm.com
[punit.agrawal@arm.com: add an empty definition for set_huge_swap_pte_at()]
Link: http://lkml.kernel.org/r/20170525171331.31469-1-punit.agrawal@arm.com
Link: http://lkml.kernel.org/r/20170522133604.11392-6-punit.agrawal@arm.com
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 31e665fbcf762aac681b519ea60017b6f36602be..46bfb702e7d62ac021505d848b94fcdba638838e 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -516,6 +516,14 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm)
 {
        atomic_long_sub(l, &mm->hugetlb_usage);
 }
+
+#ifndef set_huge_swap_pte_at
+static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
+                                       pte_t *ptep, pte_t pte, unsigned long sz)
+{
+       set_huge_pte_at(mm, addr, ptep, pte);
+}
+#endif
 #else  /* CONFIG_HUGETLB_PAGE */
 struct hstate {};
 #define alloc_huge_page(v, a, r) NULL
@@ -565,6 +573,11 @@ static inline void hugetlb_report_usage(struct seq_file *f, struct mm_struct *m)
 static inline void hugetlb_count_sub(long l, struct mm_struct *mm)
 {
 }
+
+static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
+                                       pte_t *ptep, pte_t pte, unsigned long sz)
+{
+}
 #endif /* CONFIG_HUGETLB_PAGE */
 
 static inline spinlock_t *huge_pte_lock(struct hstate *h,

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3dbe3e25797529fdb1457b90c4705d9cbd594310..51d31352a5bfd4f23d7ed3cfdbf8933956b286ff 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3276,9 +3276,10 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
                                 */
                                make_migration_entry_read(&swp_entry);
                                entry = swp_entry_to_pte(swp_entry);
-                               set_huge_pte_at(src, addr, src_pte, entry);
+                               set_huge_swap_pte_at(src, addr, src_pte,
+                                                    entry, sz);
                        }
-                       set_huge_pte_at(dst, addr, dst_pte, entry);
+                       set_huge_swap_pte_at(dst, addr, dst_pte, entry, sz);
                } else {
                        if (cow) {
                                huge_ptep_set_wrprotect(src, addr, src_pte);
@@ -4295,7 +4296,8 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 
                                make_migration_entry_read(&entry);
                                newpte = swp_entry_to_pte(entry);
-                               set_huge_pte_at(mm, address, ptep, newpte);
+                               set_huge_swap_pte_at(mm, address, ptep,
+                                                    newpte, huge_page_size(h));
                                pages++;
                        }
                        spin_unlock(ptl);