+ mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage.patch added to -mm tree

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

The patch titled
     Subject: mm, hugetlb, hwpoison: separate branch for free and in-use hugepage
has been added to the -mm tree.  Its filename is
     mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage.patch

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------------------------------------------------------
From: Naoya Horiguchi <naoya.horiguchi@nec.com>
Subject: mm, hugetlb, hwpoison: separate branch for free and in-use hugepage

We know that HPageFreed pages should have page refcount 0, so
get_page_unless_zero() always fails and returns 0.  So explicitly separate
the branch based on page state for minor optimization and better
readability.

Link: https://lkml.kernel.org/r/20220415041848.GA3034499@ik1-406-35019.vs.sakura.ne.jp
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c        |    4 +++-
 mm/memory-failure.c |    4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage
+++ a/mm/hugetlb.c
@@ -6831,7 +6831,9 @@ int get_hwpoison_huge_page(struct page *
 	spin_lock_irq(&hugetlb_lock);
 	if (PageHeadHuge(page)) {
 		*hugetlb = true;
-		if (HPageFreed(page) || HPageMigratable(page))
+		if (HPageFreed(page))
+			ret = 0;
+		else if (HPageMigratable(page))
 			ret = get_page_unless_zero(page);
 		else
 			ret = -EBUSY;
--- a/mm/memory-failure.c~mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage
+++ a/mm/memory-failure.c
@@ -1518,7 +1518,9 @@ int __get_huge_page_for_hwpoison(unsigne
 	if (flags & MF_COUNT_INCREASED) {
 		ret = 1;
 		count_increased = true;
-	} else if (HPageFreed(head) || HPageMigratable(head)) {
+	} else if (HPageFreed(head)) {
+		ret = 0;
+	} else if (HPageMigratable(head)) {
 		ret = get_page_unless_zero(head);
 		if (ret)
 			count_increased = true;
_

Patches currently in -mm which might be from naoya.horiguchi@nec.com are

mm-hwpoison-fix-race-between-hugetlb-free-demotion-and-memory_failure_hugetlb.patch
mm-hwpoison-put-page-in-already-hwpoisoned-case-with-mf_count_increased.patch
revert-mm-memory-failurec-fix-race-with-changing-page-compound-again.patch
mm-hugetlb-hwpoison-separate-branch-for-free-and-in-use-hugepage.patch