[125/227] mm/memory-failure.c: make non-LRU movable pages unhandlable

Commit Message

Andrew Morton March 22, 2022, 9:44 p.m. UTC

From: Miaohe Lin <[e-mail]>
Subject: mm/memory-failure.c: make non-LRU movable pages unhandlable

We can not really handle non-LRU movable pages in memory failure. 
Typically they are balloon, zsmalloc, etc.  Assuming we run into a base
(4K) non-LRU movable page, we could reach as far as identify_page_state(),
it should not fall into any category except me_unknown.

For the non-LRU compound movable pages, they could be taken for transhuge
pages but it's unexpected to split non-LRU movable pages using
split_huge_page_to_list in memory_failure.  So we could just simply make
non-LRU movable pages unhandlable to avoid these possible nasty cases.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Suggested-by: Yang Shi <[e-mail]>
Reviewed-by: Yang Shi <[e-mail]>
Acked-by: Naoya Horiguchi <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Tony Luck <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory-failure.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

Patch

--- a/mm/memory-failure.c~mm-memory-failurec-make-non-lru-movable-pages-unhandlable
+++ a/mm/memory-failure.c
@@ -1176,12 +1176,18 @@  void ClearPageHWPoisonTakenOff(struct pa
  * does not return true for hugetlb or device memory pages, so it's assumed
  * to be called only in the context where we never have such pages.
  */
-static inline bool HWPoisonHandlable(struct page *page)
+static inline bool HWPoisonHandlable(struct page *page, unsigned long flags)
 {
-	return PageLRU(page) || __PageMovable(page) || is_free_buddy_page(page);
+	bool movable = false;
+
+	/* Soft offline could mirgate non-LRU movable pages */
+	if ((flags & MF_SOFT_OFFLINE) && __PageMovable(page))
+		movable = true;
+
+	return movable || PageLRU(page) || is_free_buddy_page(page);
 }
 
-static int __get_hwpoison_page(struct page *page)
+static int __get_hwpoison_page(struct page *page, unsigned long flags)
 {
 	struct page *head = compound_head(page);
 	int ret = 0;
@@ -1196,7 +1202,7 @@  static int __get_hwpoison_page(struct pa
 	 * for any unsupported type of page in order to reduce the risk of
 	 * unexpected races caused by taking a page refcount.
 	 */
-	if (!HWPoisonHandlable(head))
+	if (!HWPoisonHandlable(head, flags))
 		return -EBUSY;
 
 	if (get_page_unless_zero(head)) {
@@ -1221,7 +1227,7 @@  static int get_any_page(struct page *p,
 
 try_again:
 	if (!count_increased) {
-		ret = __get_hwpoison_page(p);
+		ret = __get_hwpoison_page(p, flags);
 		if (!ret) {
 			if (page_count(p)) {
 				/* We raced with an allocation, retry. */
@@ -1249,7 +1255,7 @@  try_again:
 		}
 	}
 
-	if (PageHuge(p) || HWPoisonHandlable(p)) {
+	if (PageHuge(p) || HWPoisonHandlable(p, flags)) {
 		ret = 1;
 	} else {
 		/*
@@ -2302,7 +2308,7 @@  int soft_offline_page(unsigned long pfn,
 
 retry:
 	get_online_mems();
-	ret = get_hwpoison_page(page, flags);
+	ret = get_hwpoison_page(page, flags | MF_SOFT_OFFLINE);
 	put_online_mems();
 
 	if (ret > 0) {