mm/rmap: update to new mmu_notifier semantic v2

Jérôme Glisse · torvalds · commit 369ea8242c0f · 2017-08-31T16:12:59.000-07:00
Replace all mmu_notifier_invalidate_page() calls by *_invalidate_range()
and make sure it is bracketed by calls to *_invalidate_range_start()/end().

Note that because we can not presume the pmd value or pte value we have
to assume the worst 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 &lt;&lt; compound_order(page)
  - fix PageHuge() case in try_to_unmap_one()

Signed-off-by: Jérôme Glisse &lt;jglisse@redhat.com&gt;
Reviewed-by: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Ross Zwisler &lt;ross.zwisler@linux.intel.com&gt;
Cc: Bernhard Held &lt;berny156@gmx.de&gt;
Cc: Adam Borowski &lt;kilobyte@angband.pl&gt;
Cc: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
Cc: Wanpeng Li &lt;kernellwp@gmail.com&gt;
Cc: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Cc: Takashi Iwai &lt;tiwai@suse.de&gt;
Cc: Nadav Amit &lt;nadav.amit@gmail.com&gt;
Cc: Mike Galbraith &lt;efault@gmx.de&gt;
Cc: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Cc: axie &lt;axie@amd.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git 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;
 }
 
