diff mbox series

[2/5] mm: soft-offline: clean up soft_offline_page()

Message ID 20190402145302.28613-3-andrea.righi@canonical.com
State New
Headers show
Series CVE-2019-10124 - hwpoison memory DoS | expand

Commit Message

Andrea Righi April 2, 2019, 2:52 p.m. UTC 
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

soft_offline_page() has some deeply indented code, that's the sign of
demand for cleanup.  So let's do this.  No functionality change.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

CVE-2019-10124

(backported from commit acc14dc4bd484f1fc8c227dd9fc2a1e592312d2b)
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
 mm/memory-failure.c | 78 ++++++++++++++++++++++++++++-----------------
 1 file changed, 49 insertions(+), 29 deletions(-)
diff mbox series

Patch

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 6de1daa1fcc7..25c4dc2035c9 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1725,6 +1725,49 @@  static int __soft_offline_page(struct page *page, int flags)
 	return ret;
 }
 
+static int soft_offline_in_use_page(struct page *page, int flags)
+{
+	int ret;
+	struct page *hpage = compound_head(page);
+
+	if (!PageHuge(page) && PageTransHuge(hpage)) {
+		lock_page(hpage);
+		ret = split_huge_page(hpage);
+		unlock_page(hpage);
+		if (unlikely(ret || PageTransCompound(page) ||
+			     !PageAnon(page))) {
+			pr_info("soft offline: %#lx: failed to split THP\n",
+				page_to_pfn(page));
+			if (flags & MF_COUNT_INCREASED)
+				put_hwpoison_page(hpage);
+			return -EBUSY;
+		}
+		get_hwpoison_page(page);
+		put_hwpoison_page(hpage);
+	}
+
+	if (PageHuge(page))
+		ret = soft_offline_huge_page(page, flags);
+	else
+		ret = __soft_offline_page(page, flags);
+
+	return ret;
+}
+
+static void soft_offline_free_page(struct page *page)
+{
+	if (PageHuge(page)) {
+		struct page *hpage = compound_head(page);
+
+		set_page_hwpoison_huge_page(hpage);
+		if (!dequeue_hwpoisoned_huge_page(hpage))
+			num_poisoned_pages_add(1 << compound_order(hpage));
+	} else {
+		if (!TestSetPageHWPoison(page))
+			num_poisoned_pages_inc();
+	}
+}
+
 /**
  * soft_offline_page - Soft offline a page.
  * @page: page to offline
@@ -1751,7 +1794,6 @@  int soft_offline_page(struct page *page, int flags)
 {
 	int ret;
 	unsigned long pfn = page_to_pfn(page);
-	struct page *hpage = compound_head(page);
 
 	if (PageHWPoison(page)) {
 		pr_info("soft offline: %#lx page already poisoned\n", pfn);
@@ -1759,37 +1801,15 @@  int soft_offline_page(struct page *page, int flags)
 			put_hwpoison_page(page);
 		return -EBUSY;
 	}
-	if (!PageHuge(page) && PageTransHuge(hpage)) {
-		lock_page(page);
-		ret = split_huge_page(hpage);
-		unlock_page(page);
-		if (unlikely(ret)) {
-			pr_info("soft offline: %#lx: failed to split THP\n",
-				pfn);
-			if (flags & MF_COUNT_INCREASED)
-				put_hwpoison_page(page);
-			return -EBUSY;
-		}
-	}
 
 	get_online_mems();
-
 	ret = get_any_page(page, pfn, flags);
 	put_online_mems();
-	if (ret > 0) { /* for in-use pages */
-		if (PageHuge(page))
-			ret = soft_offline_huge_page(page, flags);
-		else
-			ret = __soft_offline_page(page, flags);
-	} else if (ret == 0) { /* for free pages */
-		if (PageHuge(page)) {
-			set_page_hwpoison_huge_page(hpage);
-			if (!dequeue_hwpoisoned_huge_page(hpage))
-				num_poisoned_pages_add(1 << compound_order(hpage));
-		} else {
-			if (!TestSetPageHWPoison(page))
-				num_poisoned_pages_inc();
-		}
-	}
+
+	if (ret > 0)
+		ret = soft_offline_in_use_page(page, flags);
+	else if (ret == 0)
+		soft_offline_free_page(page);
+
 	return ret;
 }