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From:   Naoya Horiguchi <naoya.horiguchi@linux.dev>
To:     linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Liu Shixin <liushixin2@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Oscar Salvador <osalvador@suse.de>,
        Muchun Song <songmuchun@bytedance.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        linux-kernel@vger.kernel.org
Subject: [mm-unstable PATCH v4 7/9] mm, hwpoison: make __page_handle_poison returns int
Date:   Mon,  4 Jul 2022 10:33:10 +0900
Message-Id: <20220704013312.2415700-8-naoya.horiguchi@linux.dev>
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From: Naoya Horiguchi <naoya.horiguchi@nec.com>

__page_handle_poison() returns bool that shows whether
take_page_off_buddy() has passed or not now.  But we will want to
distinguish another case of "dissolve has passed but taking off failed"
by its return value. So change the type of the return value.
No functional change.

Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
---
v2 -> v3:
- move deleting "res = MF_FAILED" to the later patch. (by Miaohe)
---
 mm/memory-failure.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 4233b21328a5..c8939a39fbe6 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -71,7 +71,13 @@ atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
 static bool hw_memory_failure __read_mostly = false;
 
-static bool __page_handle_poison(struct page *page)
+/*
+ * Return values:
+ *   1:   the page is dissolved (if needed) and taken off from buddy,
+ *   0:   the page is dissolved (if needed) and not taken off from buddy,
+ *   < 0: failed to dissolve.
+ */
+static int __page_handle_poison(struct page *page)
 {
 	int ret;
 
@@ -81,7 +87,7 @@ static bool __page_handle_poison(struct page *page)
 		ret = take_page_off_buddy(page);
 	zone_pcp_enable(page_zone(page));
 
-	return ret > 0;
+	return ret;
 }
 
 static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
@@ -91,7 +97,7 @@ static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, boo
 		 * Doing this check for free pages is also fine since dissolve_free_huge_page
 		 * returns 0 for non-hugetlb pages as well.
 		 */
-		if (!__page_handle_poison(page))
+		if (__page_handle_poison(page) <= 0)
 			/*
 			 * We could fail to take off the target page from buddy
 			 * for example due to racy page allocation, but that's
@@ -1086,7 +1092,7 @@ static int me_huge_page(struct page_state *ps, struct page *p)
 		 * subpages.
 		 */
 		put_page(hpage);
-		if (__page_handle_poison(p)) {
+		if (__page_handle_poison(p) > 0) {
 			page_ref_inc(p);
 			res = MF_RECOVERED;
 		}
@@ -1850,7 +1856,7 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 	if (res == 0) {
 		unlock_page(head);
 		res = MF_FAILED;
-		if (__page_handle_poison(p)) {
+		if (__page_handle_poison(p) > 0) {
 			page_ref_inc(p);
 			res = MF_RECOVERED;
 		}
-- 
2.25.1