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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jane Chu <jane.chu@oracle.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 669/677] mm/memory-failure: unnecessary amount of unmapping
Date:   Wed, 12 May 2021 16:51:55 +0200
Message-Id: <20210512144859.588626747@linuxfoundation.org>
In-Reply-To: <20210512144837.204217980@linuxfoundation.org>
References: <20210512144837.204217980@linuxfoundation.org>
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From: Jane Chu <jane.chu@oracle.com>

[ Upstream commit 4d75136be8bf3ae01b0bc3e725b2cdc921e103bd ]

It appears that unmap_mapping_range() actually takes a 'size' as its third
argument rather than a location, the current calling fashion causes
unnecessary amount of unmapping to occur.

Link: https://lkml.kernel.org/r/20210420002821.2749748-1-jane.chu@oracle.com
Fixes: 6100e34b2526e ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/memory-failure.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 24210c9bd843..bd3945446d47 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1368,7 +1368,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		 * communicated in siginfo, see kill_proc()
 		 */
 		start = (page->index << PAGE_SHIFT) & ~(size - 1);
-		unmap_mapping_range(page->mapping, start, start + size, 0);
+		unmap_mapping_range(page->mapping, start, size, 0);
 	}
 	kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags);
 	rc = 0;
-- 
2.30.2