pve-kernel-qoup/swapops-0002-Revert-mm-ksm-convert-write_protect_page-to-use-page.patch

From 40e1fa51bc8aa3df1d3a23711b5de62d8251bff5 Mon Sep 17 00:00:00 2001
From: Seth Forshee <seth.forshee@canonical.com>
Date: Wed, 3 May 2017 08:34:52 -0500
Subject: [PATCH 2/4] Revert "mm, ksm: convert write_protect_page() to use
 page_vma_mapped_walk()"

This reverts commit 3000e033152a70fa139765b4dbb5baec46b1cc1b.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---
 mm/ksm.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 9dd2e58fb6dc..fed4afd8293b 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -856,35 +856,33 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 			      pte_t *orig_pte)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	struct page_vma_mapped_walk pvmw = {
-		.page = page,
-		.vma = vma,
-	};
+	unsigned long addr;
+	pte_t *ptep;
+	spinlock_t *ptl;
 	int swapped;
 	int err = -EFAULT;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
 
-	pvmw.address = page_address_in_vma(page, vma);
-	if (pvmw.address == -EFAULT)
+	addr = page_address_in_vma(page, vma);
+	if (addr == -EFAULT)
 		goto out;
 
 	BUG_ON(PageTransCompound(page));
 
-	mmun_start = pvmw.address;
-	mmun_end   = pvmw.address + PAGE_SIZE;
+	mmun_start = addr;
+	mmun_end   = addr + PAGE_SIZE;
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 
-	if (!page_vma_mapped_walk(&pvmw))
+	ptep = page_check_address(page, mm, addr, &ptl, 0);
+	if (!ptep)
 		goto out_mn;
-	if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
-		goto out_unlock;
 
-	if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
+	if (pte_write(*ptep) || pte_dirty(*ptep)) {
 		pte_t entry;
 
 		swapped = PageSwapCache(page);
-		flush_cache_page(vma, pvmw.address, page_to_pfn(page));
+		flush_cache_page(vma, addr, page_to_pfn(page));
 		/*
 		 * Ok this is tricky, when get_user_pages_fast() run it doesn't
 		 * take any lock, therefore the check that we are going to make
@@ -894,25 +892,25 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 		 * this assure us that no O_DIRECT can happen after the check
 		 * or in the middle of the check.
 		 */
-		entry = ptep_clear_flush_notify(vma, pvmw.address, pvmw.pte);
+		entry = ptep_clear_flush_notify(vma, addr, ptep);
 		/*
 		 * Check that no O_DIRECT or similar I/O is in progress on the
 		 * page
 		 */
 		if (page_mapcount(page) + 1 + swapped != page_count(page)) {
-			set_pte_at(mm, pvmw.address, pvmw.pte, entry);
+			set_pte_at(mm, addr, ptep, entry);
 			goto out_unlock;
 		}
 		if (pte_dirty(entry))
 			set_page_dirty(page);
 		entry = pte_mkclean(pte_wrprotect(entry));
-		set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
+		set_pte_at_notify(mm, addr, ptep, entry);
 	}
-	*orig_pte = *pvmw.pte;
+	*orig_pte = *ptep;
 	err = 0;
 
 out_unlock:
-	page_vma_mapped_walk_done(&pvmw);
+	pte_unmap_unlock(ptep, ptl);
 out_mn:
 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 out:
-- 
2.7.4