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From:   Oscar Salvador <osalvador@suse.de>
To:     akpm@linux-foundation.org
Cc:     mhocko@suse.com, linux-mm@kvack.org, mike.kravetz@oracle.com,
        david@redhat.com, aneesh.kumar@linux.vnet.ibm.com,
        naoya.horiguchi@nec.com, linux-kernel@vger.kernel.org,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Oscar Salvador <osalvador@suse.com>
Subject: [PATCH v4 05/15] mm,hwpoison-inject: don't pin for hwpoison_filter
Date:   Thu, 16 Jul 2020 14:37:59 +0200
Message-Id: <20200716123810.25292-6-osalvador@suse.de>
In-Reply-To: <20200716123810.25292-1-osalvador@suse.de>
References: <20200716123810.25292-1-osalvador@suse.de>
Sender: linux-kernel-owner@vger.kernel.org
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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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 <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Oscar Salvador <osalvador@suse.com>
---
 mm/hwpoison-inject.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index e488876b168a..1ae1ebc2b9b1 100644
--- a/mm/hwpoison-inject.c
+++ b/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)
-- 
2.26.2