mm: add pt_mm to struct page

For pgd page table pages, x86 overloads the page->index field to store a
pointer to the mm_struct.  Rename this to pt_mm so it's visible to other
users.

Link: http://lkml.kernel.org/r/20180518194519.3820-13-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index ffc8c13c50e4491941a1f795e2339964305e51da..938dbcd46b97b2827400e2f71813f50bb26622d4 100644 (file)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -114,13 +114,12 @@ static inline void pgd_list_del(pgd_t *pgd)
 
 static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
 {
-       BUILD_BUG_ON(sizeof(virt_to_page(pgd)->index) < sizeof(mm));
-       virt_to_page(pgd)->index = (pgoff_t)mm;
+       virt_to_page(pgd)->pt_mm = mm;
 }
 
 struct mm_struct *pgd_page_get_mm(struct page *page)
 {
-       return (struct mm_struct *)page->index;
+       return page->pt_mm;
 }
 
 static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 9b45760cc797a7b750a33e414d7e936fde9fad03..811aa0c71e1a0894cf301a63ee2ba60fa33bb2c3 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -139,7 +139,7 @@ struct page {
                        unsigned long _pt_pad_1;        /* compound_head */
                        pgtable_t pmd_huge_pte; /* protected by page->ptl */
                        unsigned long _pt_pad_2;        /* mapping */
-                       unsigned long _pt_pad_3;
+                       struct mm_struct *pt_mm;        /* x86 pgds only */
 #if ALLOC_SPLIT_PTLOCKS
                        spinlock_t *ptl;
 #else