[PATCH v3 1/4] mm: change page type prior to adding page table entry

[Pasha Tatashin <pasha.tatashin@soleen.com>]

There are  a few places where we first update the entry in the user page
table, and later change the struct page to indicate that this is
anonymous or file page.

In most places, however, we first configure the page metadata and then
insert entries into the page table. Page table check, will use
the information from struct page to verify the type of entry is
inserted.

Change the order in all places to first update struct page, and later to
update page table.

This means that we first do calls that may change the type of page (anon
or file):

	page_move_anon_rmap
	page_add_anon_rmap
	do_page_add_anon_rmap
	page_add_new_anon_rmap
	page_add_file_rmap
	hugepage_add_anon_rmap
	hugepage_add_new_anon_rmap

And after that do calls that add entries to the page table:

	set_huge_pte_at
	set_pte_at

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 mm/hugetlb.c  | 6 +++---
 mm/memory.c   | 9 +++++----
 mm/migrate.c  | 5 ++---
 mm/swapfile.c | 4 ++--
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a1baa198519a..61895cc01d09 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4684,8 +4684,8 @@ hugetlb_install_page(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr
 		     struct page *new_page)
 {
 	__SetPageUptodate(new_page);
-	set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1));
 	hugepage_add_new_anon_rmap(new_page, vma, addr);
+	set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1));
 	hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm);
 	ClearHPageRestoreReserve(new_page);
 	SetHPageMigratable(new_page);
@@ -5259,10 +5259,10 @@ static vm_fault_t hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 		/* Break COW */
 		huge_ptep_clear_flush(vma, haddr, ptep);
 		mmu_notifier_invalidate_range(mm, range.start, range.end);
-		set_huge_pte_at(mm, haddr, ptep,
-				make_huge_pte(vma, new_page, 1));
 		page_remove_rmap(old_page, true);
 		hugepage_add_new_anon_rmap(new_page, vma, haddr);
+		set_huge_pte_at(mm, haddr, ptep,
+				make_huge_pte(vma, new_page, 1));
 		SetHPageMigratable(new_page);
 		/* Make the old page be freed below */
 		new_page = old_page;
diff --git a/mm/memory.c b/mm/memory.c
index 71e475d440b0..11cb28a2ca54 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -720,8 +720,6 @@ static void restore_exclusive_pte(struct vm_area_struct *vma,
 	else if (is_writable_device_exclusive_entry(entry))
 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
 
-	set_pte_at(vma->vm_mm, address, ptep, pte);
-
 	/*
 	 * No need to take a page reference as one was already
 	 * created when the swap entry was made.
@@ -735,6 +733,8 @@ static void restore_exclusive_pte(struct vm_area_struct *vma,
 		 */
 		WARN_ON_ONCE(!PageAnon(page));
 
+	set_pte_at(vma->vm_mm, address, ptep, pte);
+
 	if (vma->vm_flags & VM_LOCKED)
 		mlock_vma_page(page);
 
@@ -3635,8 +3635,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		pte = pte_mkuffd_wp(pte);
 		pte = pte_wrprotect(pte);
 	}
-	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
-	arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
 	vmf->orig_pte = pte;
 
 	/* ksm created a completely new copy */
@@ -3647,6 +3645,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
 	}
 
+	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
+	arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
+
 	swap_free(entry);
 	if (mem_cgroup_swap_full(page) ||
 	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
diff --git a/mm/migrate.c b/mm/migrate.c
index c9296d63878d..f943a2d99de7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -237,20 +237,19 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
 
 			pte = pte_mkhuge(pte);
 			pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
-			set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 			if (PageAnon(new))
 				hugepage_add_anon_rmap(new, vma, pvmw.address);
 			else
 				page_dup_rmap(new, true);
+			set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 		} else
 #endif
 		{
-			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
-
 			if (PageAnon(new))
 				page_add_anon_rmap(new, vma, pvmw.address, false);
 			else
 				page_add_file_rmap(new, false);
+			set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 		}
 		if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
 			mlock_vma_page(new);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index e59e08ef46e1..e64207e2ef1d 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1917,14 +1917,14 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 	dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
 	inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
 	get_page(page);
-	set_pte_at(vma->vm_mm, addr, pte,
-		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
 	if (page == swapcache) {
 		page_add_anon_rmap(page, vma, addr, false);
 	} else { /* ksm created a completely new copy */
 		page_add_new_anon_rmap(page, vma, addr, false);
 		lru_cache_add_inactive_or_unevictable(page, vma);
 	}
+	set_pte_at(vma->vm_mm, addr, pte,
+		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
 	swap_free(entry);
 out:
 	pte_unmap_unlock(pte, ptl);
-- 
2.34.1.307.g9b7440fafd-goog