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From:   zhenwei pi <pizhenwei@bytedance.com>
To:     akpm@linux-foundation.org, naoya.horiguchi@nec.com
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        zhenwei pi <pizhenwei@bytedance.com>
Subject: [PATCH v2 2/5] mm/memory-failure.c: simplify num_poisoned_pages_dec
Date:   Mon,  9 May 2022 18:56:38 +0800
Message-Id: <20220509105641.491313-3-pizhenwei@bytedance.com>
In-Reply-To: <20220509105641.491313-1-pizhenwei@bytedance.com>
References: <20220509105641.491313-1-pizhenwei@bytedance.com>
MIME-Version: 1.0
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Precedence: bulk

Don't decrease the number of poisoned pages in page_alloc.c, let the
memory-failure.c do inc/dec poisoned pages only.

Also simplify unpoison_memory(), only decrease the number of
poisoned pages when:
 - TestClearPageHWPoison() succeed
 - put_page_back_buddy succeed

After decreasing, print necessary log.

Finally, remove clear_page_hwpoison() and unpoison_taken_off_page().

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
 mm/memory-failure.c | 37 +++++++++----------------------------
 mm/page_alloc.c     |  1 -
 2 files changed, 9 insertions(+), 29 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 46d9fb612dcc..ece05858568f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2101,28 +2101,6 @@ core_initcall(memory_failure_init);
 		pr_info(fmt, pfn);			\
 })
 
-static inline int clear_page_hwpoison(struct ratelimit_state *rs, struct page *p)
-{
-	if (TestClearPageHWPoison(p)) {
-		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
-				 page_to_pfn(p), rs);
-		num_poisoned_pages_dec();
-		return 1;
-	}
-	return 0;
-}
-
-static inline int unpoison_taken_off_page(struct ratelimit_state *rs,
-					  struct page *p)
-{
-	if (put_page_back_buddy(p)) {
-		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
-				 page_to_pfn(p), rs);
-		return 0;
-	}
-	return -EBUSY;
-}
-
 /**
  * unpoison_memory - Unpoison a previously poisoned page
  * @pfn: Page number of the to be unpoisoned page
@@ -2140,6 +2118,7 @@ int unpoison_memory(unsigned long pfn)
 	struct page *page;
 	struct page *p;
 	int ret = -EBUSY;
+	int freeit = 0;
 	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
 					DEFAULT_RATELIMIT_BURST);
 
@@ -2180,18 +2159,15 @@ int unpoison_memory(unsigned long pfn)
 
 	ret = get_hwpoison_page(p, MF_UNPOISON);
 	if (!ret) {
-		if (clear_page_hwpoison(&unpoison_rs, page))
-			ret = 0;
-		else
-			ret = -EBUSY;
+		ret = TestClearPageHWPoison(page) ? 0 : -EBUSY;
 	} else if (ret < 0) {
 		if (ret == -EHWPOISON) {
-			ret = unpoison_taken_off_page(&unpoison_rs, p);
+			ret = put_page_back_buddy(p) ? 0 : -EBUSY;
 		} else
 			unpoison_pr_info("Unpoison: failed to grab page %#lx\n",
 					 pfn, &unpoison_rs);
 	} else {
-		int freeit = clear_page_hwpoison(&unpoison_rs, p);
+		freeit = !!TestClearPageHWPoison(p);
 
 		put_page(page);
 		if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) {
@@ -2202,6 +2178,11 @@ int unpoison_memory(unsigned long pfn)
 
 unlock_mutex:
 	mutex_unlock(&mf_mutex);
+	if (!ret || freeit) {
+		num_poisoned_pages_dec();
+		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
+				 page_to_pfn(p), &unpoison_rs);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(unpoison_memory);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0e42038382c1..d710846ef653 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -9625,7 +9625,6 @@ bool put_page_back_buddy(struct page *page)
 		ClearPageHWPoisonTakenOff(page);
 		__free_one_page(page, pfn, zone, 0, migratetype, FPI_NONE);
 		if (TestClearPageHWPoison(page)) {
-			num_poisoned_pages_dec();
 			ret = true;
 		}
 	}
-- 
2.20.1