+ mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: memory-failure: fix race window when trying to get hugetlb folio
has been added to the -mm mm-unstable branch.  Its filename is
     mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm: memory-failure: fix race window when trying to get hugetlb folio
Date: Tue, 11 Jul 2023 13:50:16 +0800

page_folio() is fetched before calling get_hwpoison_hugetlb_folio()
without hugetlb_lock being held.  So hugetlb page could be demoted before
get_hwpoison_hugetlb_folio() holding hugetlb_lock but after page_folio()
is fetched.  So get_hwpoison_hugetlb_folio() will hold unexpected extra
refcnt of hugetlb folio while leaving demoted page un-refcnted.

Link: https://lkml.kernel.org/r/20230711055016.2286677-9-linmiaohe@huawei.com
Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory-failure.c |   20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio
+++ a/mm/memory-failure.c
@@ -1383,8 +1383,15 @@ static int __get_hwpoison_page(struct pa
 	bool hugetlb = false;
 
 	ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, false);
-	if (hugetlb)
-		return ret;
+	if (hugetlb) {
+		/* Make sure hugetlb demotion did not happen from under us. */
+		if (folio == page_folio(page))
+			return ret;
+		if (ret > 0) {
+			folio_put(folio);
+			folio = page_folio(page);
+		}
+	}
 
 	/*
 	 * This check prevents from calling folio_try_get() for any
@@ -1473,8 +1480,13 @@ static int __get_unpoison_page(struct pa
 	bool hugetlb = false;
 
 	ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, true);
-	if (hugetlb)
-		return ret;
+	if (hugetlb) {
+		/* Make sure hugetlb demotion did not happen from under us. */
+		if (folio == page_folio(page))
+			return ret;
+		if (ret > 0)
+			folio_put(folio);
+	}
 
 	/*
 	 * PageHWPoisonTakenOff pages are not only marked as PG_hwpoison,
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-mm_initc-update-obsolete-comment-in-get_pfn_range_for_nid.patch
mm-memory-failure-fix-unexpected-return-value-in-soft_offline_page.patch
mm-memory-failure-fix-potential-page-refcnt-leak-in-memory_failure.patch
mm-memory-failure-remove-unneeded-page-state-check-in-shake_page.patch
memory-tier-use-helper-function-destroy_memory_type.patch
mm-memory-failure-remove-unneeded-inline-annotation.patch
mm-mm_initc-remove-obsolete-macro-hash_small.patch
mm-page_alloc-avoid-false-page-outside-zone-error-info.patch
memory-tier-rename-destroy_memory_type-to-put_memory_type.patch
mm-remove-obsolete-comment-above-struct-per_cpu_pages.patch
mm-memcg-minor-cleanup-for-mem_cgroup_id_max.patch
mm-memory-failure-remove-unneeded-pagehuge-check.patch
mm-memory-failure-ensure-moving-hwpoison-flag-to-the-raw-error-pages.patch
mm-memory-failure-dont-account-hwpoison_filter-filtered-pages.patch
mm-memory-failure-use-local-variable-huge-to-check-hugetlb-page.patch
mm-memory-failure-remove-unneeded-header-files.patch
mm-memory-failure-minor-cleanup-for-comments-and-codestyle.patch
mm-memory-failure-fetch-compound-head-after-extra-page-refcnt-is-held.patch
mm-memory-failure-fix-race-window-when-trying-to-get-hugetlb-folio.patch