From e73ea59505d91aa5ff0ba9e650852fbd275e1da9 Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Thu, 2 Sep 2021 14:53:42 -0700
Subject: [PATCH] mm: gup: fix potential pgmap refcnt leak in
__gup_device_huge()
References: git fixes (mm)
Patch-mainline: v5.15-rc1
Git-commit: 6401c4eb57f947a49eb144b5b0787cde3318e82e
When failed to try_grab_page, put_dev_pagemap() is missed. So pgmap
refcnt will leak in this case. Also we remove the check for pgmap against
NULL as it's also checked inside the put_dev_pagemap().
[akpm@linux-foundation.org: simplify, cleanup]
[akpm@linux-foundation.org: fix return value]
Link: https://lkml.kernel.org/r/20210807093620.21347-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages")
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/gup.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 9f5b9a93ae21..a10c48ef613c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2240,6 +2240,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
{
int nr_start = *nr;
struct dev_pagemap *pgmap = NULL;
+ int ret = 1;
do {
struct page *page = pfn_to_page(pfn);
@@ -2247,21 +2248,22 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
pgmap = get_dev_pagemap(pfn, pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
- return 0;
+ ret = 0;
+ break;
}
SetPageReferenced(page);
pages[*nr] = page;
if (unlikely(!try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
- return 0;
+ ret = 0;
+ break;
}
(*nr)++;
pfn++;
} while (addr += PAGE_SIZE, addr != end);
- if (pgmap)
- put_dev_pagemap(pgmap);
- return 1;
+ put_dev_pagemap(pgmap);
+ return ret;
}
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,