[029/192] mm/hwpoison: disable pcp for page_handle_poison()

Commit Message

Andrew Morton July 1, 2021, 1:48 a.m. UTC

From: Naoya Horiguchi <[e-mail]>
Subject: mm/hwpoison: disable pcp for page_handle_poison()

Recent changes by patch "mm/page_alloc: allow high-order pages to be
stored on the per-cpu lists" makes kernels determine whether to use pcp by
pcp_allowed_order(), which breaks soft-offline for hugetlb pages.

Soft-offline dissolves a migration source page, then removes it from buddy
free list, so it's assumed that any subpage of the soft-offlined hugepage
are recognized as a buddy page just after returning from
dissolve_free_huge_page().  pcp_allowed_order() returns true for hugetlb,
so this assumption is no longer true.

So disable pcp during dissolve_free_huge_page() and take_page_off_buddy()
to prevent soft-offlined hugepages from linking to pcp lists. 
Soft-offline should not be common events so the impact on performance
should be minimal.  And I think that the optimization of Mel's patch could
benefit to hugetlb so zone_pcp_disable() is called only in hwpoison
context.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Naoya Horiguchi <[e-mail]>
Acked-by: Mel Gorman <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory-failure.c |   19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

Patch

--- a/mm/memory-failure.c~mm-hwpoison-disable-pcp-for-page_handle_poison
+++ a/mm/memory-failure.c
@@ -66,6 +66,19 @@  int sysctl_memory_failure_recovery __rea
 
 atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
+static bool __page_handle_poison(struct page *page)
+{
+	bool ret;
+
+	zone_pcp_disable(page_zone(page));
+	ret = dissolve_free_huge_page(page);
+	if (!ret)
+		ret = take_page_off_buddy(page);
+	zone_pcp_enable(page_zone(page));
+
+	return ret;
+}
+
 static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
 {
 	if (hugepage_or_freepage) {
@@ -73,7 +86,7 @@  static bool page_handle_poison(struct pa
 		 * Doing this check for free pages is also fine since dissolve_free_huge_page
 		 * returns 0 for non-hugetlb pages as well.
 		 */
-		if (dissolve_free_huge_page(page) || !take_page_off_buddy(page))
+		if (!__page_handle_poison(page))
 			/*
 			 * We could fail to take off the target page from buddy
 			 * for example due to racy page allocation, but that's
@@ -985,7 +998,7 @@  static int me_huge_page(struct page *p,
 		 */
 		if (PageAnon(hpage))
 			put_page(hpage);
-		if (!dissolve_free_huge_page(p) && take_page_off_buddy(p)) {
+		if (__page_handle_poison(p)) {
 			page_ref_inc(p);
 			res = MF_RECOVERED;
 		}
@@ -1446,7 +1459,7 @@  static int memory_failure_hugetlb(unsign
 			}
 			unlock_page(head);
 			res = MF_FAILED;
-			if (!dissolve_free_huge_page(p) && take_page_off_buddy(p)) {
+			if (__page_handle_poison(p)) {
 				page_ref_inc(p);
 				res = MF_RECOVERED;
 			}