mm: add orig_pte field into vm_fault

Add orig_pte field to vm_fault structure to allow ->page_mkwrite
handlers to fully handle the fault.

This also allows us to save some passing of extra arguments around.

Link: http://lkml.kernel.org/r/1479460644-25076-8-git-send-email-jack@suse.czSigned-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -298,8 +298,8 @@ struct vm_fault {
 	pgoff_t pgoff;			/* Logical page offset based on vma */
 	unsigned long address;		/* Faulting virtual address */
 	pmd_t *pmd;			/* Pointer to pmd entry matching
-					 * the 'address'
-					 */
+					 * the 'address' */
+	pte_t orig_pte;			/* Value of PTE at the time of fault */
 
 	struct page *cow_page;		/* Handler may choose to COW */
 	struct page *page;		/* ->fault handlers should return a

mm/internal.h

@@ -36,7 +36,7 @@
 /* Do not use these with a slab allocator */
 #define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
 
-int do_swap_page(struct vm_fault *vmf, pte_t orig_pte);
+int do_swap_page(struct vm_fault *vmf);
 
 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
 		unsigned long floor, unsigned long ceiling);

mm/khugepaged.c

@@ -875,7 +875,6 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm,
 					unsigned long address, pmd_t *pmd,
 					int referenced)
 {
-	pte_t pteval;
 	int swapped_in = 0, ret = 0;
 	struct vm_fault vmf = {
 		.vma = vma,
@@ -893,11 +892,11 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm,
 	vmf.pte = pte_offset_map(pmd, address);
 	for (; vmf.address < address + HPAGE_PMD_NR*PAGE_SIZE;
 			vmf.pte++, vmf.address += PAGE_SIZE) {
-		pteval = *vmf.pte;
-		if (!is_swap_pte(pteval))
+		vmf.orig_pte = *vmf.pte;
+		if (!is_swap_pte(vmf.orig_pte))
 			continue;
 		swapped_in++;
-		ret = do_swap_page(&vmf, pteval);
+		ret = do_swap_page(&vmf);
 
 		/* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */
 		if (ret & VM_FAULT_RETRY) {