[PATCH 02/13] mm/rmap: update to new mmu_notifier semantic v2

[jglisse]

From: JÃrÃme Glisse <jglisse@xxxxxxxxxx>

Replacing all mmu_notifier_invalidate_page() by mmu_notifier_invalidat_range()
and making sure it is bracketed by call to mmu_notifier_invalidate_range_start/
end.

Note that because we can not presume the pmd value or pte value we have to
assume the worse and unconditionaly report an invalidation as happening.

Changed since v2:
  - try_to_unmap_one() only one call to mmu_notifier_invalidate_range()
  - compute end with PAGE_SIZE << compound_order(page)
  - fix PageHuge() case in try_to_unmap_one()

Signed-off-by: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Bernhard Held <berny156@xxxxxx>
Cc: Adam Borowski <kilobyte@xxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Wanpeng Li <kernellwp@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: axie <axie@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
 mm/rmap.c | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index c8993c63eb25..c570f82e6827 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -887,11 +887,21 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 		.address = address,
 		.flags = PVMW_SYNC,
 	};
+	unsigned long start = address, end;
 	int *cleaned = arg;
 
+	/*
+	 * We have to assume the worse case ie pmd for invalidation. Note that
+	 * the page can not be free from this function.
+	 */
+	end = min(vma->vm_end, start + (PAGE_SIZE << compound_order(page)));
+	mmu_notifier_invalidate_range_start(vma->vm_mm, start, end);
+
 	while (page_vma_mapped_walk(&pvmw)) {
+		unsigned long cstart, cend;
 		int ret = 0;
-		address = pvmw.address;
+
+		cstart = address = pvmw.address;
 		if (pvmw.pte) {
 			pte_t entry;
 			pte_t *pte = pvmw.pte;
@@ -904,6 +914,7 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 			entry = pte_wrprotect(entry);
 			entry = pte_mkclean(entry);
 			set_pte_at(vma->vm_mm, address, pte, entry);
+			cend = cstart + PAGE_SIZE;
 			ret = 1;
 		} else {
 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
@@ -918,6 +929,8 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 			entry = pmd_wrprotect(entry);
 			entry = pmd_mkclean(entry);
 			set_pmd_at(vma->vm_mm, address, pmd, entry);
+			cstart &= PMD_MASK;
+			cend = cstart + PMD_SIZE;
 			ret = 1;
 #else
 			/* unexpected pmd-mapped page? */
@@ -926,11 +939,13 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 		}
 
 		if (ret) {
-			mmu_notifier_invalidate_page(vma->vm_mm, address);
+			mmu_notifier_invalidate_range(vma->vm_mm, cstart, cend);
 			(*cleaned)++;
 		}
 	}
 
+	mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
+
 	return true;
 }
 
@@ -1324,6 +1339,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	pte_t pteval;
 	struct page *subpage;
 	bool ret = true;
+	unsigned long start = address, end;
 	enum ttu_flags flags = (enum ttu_flags)arg;
 
 	/* munlock has nothing to gain from examining un-locked vmas */
@@ -1335,6 +1351,14 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				flags & TTU_MIGRATION, page);
 	}
 
+	/*
+	 * We have to assume the worse case ie pmd for invalidation. Note that
+	 * the page can not be free in this function as call of try_to_unmap()
+	 * must hold a reference on the page.
+	 */
+	end = min(vma->vm_end, start + (PAGE_SIZE << compound_order(page)));
+	mmu_notifier_invalidate_range_start(vma->vm_mm, start, end);
+
 	while (page_vma_mapped_walk(&pvmw)) {
 		/*
 		 * If the page is mlock()d, we cannot swap it out.
@@ -1445,6 +1469,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 			if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
 				WARN_ON_ONCE(1);
 				ret = false;
+				/* We have to invalidate as we cleared the pte */
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1490,8 +1515,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 discard:
 		page_remove_rmap(subpage, PageHuge(page));
 		put_page(page);
-		mmu_notifier_invalidate_page(mm, address);
+		mmu_notifier_invalidate_range(mm, address,
+					      address + PAGE_SIZE);
 	}
+
+	mmu_notifier_invalidate_range_end(vma->vm_mm, start, end);
+
 	return ret;
 }
 
-- 
2.13.5