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Subject[PATCH 4/3] mm, hugetlb, hwpoison: separate branch for free and in-use hugepage
From: Naoya Horiguchi <naoya.horiguchi@nec.com>

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.

Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/hugetlb.c | 4 +++-
mm/memory-failure.c | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e38cbfdf3e61..3638f166e554 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6786,7 +6786,9 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
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;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5e3ad640f5bb..661079a37f29 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1517,7 +1517,9 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
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;
--
2.23.0
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