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>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3fc7217..f8e048b 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6776,7 +6776,9 @@ 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 e01a2da..9711c0e 100644 (file)
--- 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;