mm: memory-failure: fix potential page refcnt leak in memory_failure()

put_ref_page() is not called to drop extra refcnt when comes from madvise
in the case pfn is valid but pgmap is NULL leading to page refcnt leak.

Link: https://lkml.kernel.org/r/20230701072837.1994253-1-linmiaohe@huawei.com
Fixes: 1e8aaedb182d ("mm,memory_failure: always pin the page in madvise_inject_error")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 55dfe8a..881c35e 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2117,8 +2117,6 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 {
        int rc = -ENXIO;
 
-       put_ref_page(pfn, flags);
-
        /* device metadata space is not recoverable */
        if (!pgmap_pfn_valid(pgmap, pfn))
                goto out;
@@ -2193,6 +2191,7 @@ int memory_failure(unsigned long pfn, int flags)
 
                if (pfn_valid(pfn)) {
                        pgmap = get_dev_pagemap(pfn, NULL);
+                       put_ref_page(pfn, flags);
                        if (pgmap) {
                                res = memory_failure_dev_pagemap(pfn, flags,
                                                                 pgmap);