linux-kernel - [PATCH v6 03/12] mm,hwpoison-inject: don't pin for hwpoison

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Date:   Thu,  6 Aug 2020 18:49:14 +0000
From:   nao.horiguchi@...il.com
To:     linux-mm@...ck.org
Cc:     mhocko@...nel.org, akpm@...ux-foundation.org,
        mike.kravetz@...cle.com, osalvador@...e.de, tony.luck@...el.com,
        david@...hat.com, aneesh.kumar@...ux.vnet.ibm.com,
        zeil@...dex-team.ru, cai@....pw, naoya.horiguchi@....com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 03/12] mm,hwpoison-inject: don't pin for hwpoison_filter

From: Naoya Horiguchi <naoya.horiguchi@....com>

Another memory error injection interface debugfs:hwpoison/corrupt-pfn
also takes bogus refcount for hwpoison_filter(). It's justified
because this does a coarse filter, expecting that memory_failure()
redoes the check for sure.

Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
Signed-off-by: Oscar Salvador <osalvador@...e.com>
---
 mm/hwpoison-inject.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git v5.8-rc7-mmotm-2020-07-27-18-18/mm/hwpoison-inject.c v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/hwpoison-inject.c
index e488876b168a..1ae1ebc2b9b1 100644
--- v5.8-rc7-mmotm-2020-07-27-18-18/mm/hwpoison-inject.c
+++ v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/hwpoison-inject.c
@@ -26,11 +26,6 @@ static int hwpoison_inject(void *data, u64 val)
 
 	p = pfn_to_page(pfn);
 	hpage = compound_head(p);
-	/*
-	 * This implies unable to support free buddy pages.
-	 */
-	if (!get_hwpoison_page(p))
-		return 0;
 
 	if (!hwpoison_filter_enable)
 		goto inject;
@@ -40,23 +35,20 @@ static int hwpoison_inject(void *data, u64 val)
 	 * This implies unable to support non-LRU pages.
 	 */
 	if (!PageLRU(hpage) && !PageHuge(p))
-		goto put_out;
+		return 0;
 
 	/*
-	 * do a racy check with elevated page count, to make sure PG_hwpoison
-	 * will only be set for the targeted owner (or on a free page).
+	 * do a racy check to make sure PG_hwpoison will only be set for
+	 * the targeted owner (or on a free page).
 	 * memory_failure() will redo the check reliably inside page lock.
 	 */
 	err = hwpoison_filter(hpage);
 	if (err)
-		goto put_out;
+		return 0;
 
 inject:
 	pr_info("Injecting memory failure at pfn %#lx\n", pfn);
-	return memory_failure(pfn, MF_COUNT_INCREASED);
-put_out:
-	put_hwpoison_page(p);
-	return 0;
+	return memory_failure(pfn, 0);
 }
 
 static int hwpoison_unpoison(void *data, u64 val)
-- 
2.17.1