+ mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch added to -mm tree

+ mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: gup: fix potential pgmap refcnt leak in __gup_device_huge()
has been added to the -mm tree.  Its filename is
     mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm: gup: fix potential pgmap refcnt leak in __gup_device_huge()

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().

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")
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/gup.c~mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge
+++ a/mm/gup.c
@@ -2253,14 +2253,14 @@ static int __gup_device_huge(unsigned lo
 		pages[*nr] = page;
 		if (unlikely(!try_grab_page(page, flags))) {
 			undo_dev_pagemap(nr, nr_start, flags, pages);
+			put_dev_pagemap(pgmap);
 			return 0;
 		}
 		(*nr)++;
 		pfn++;
 	} while (addr += PAGE_SIZE, addr != end);
 
-	if (pgmap)
-		put_dev_pagemap(pgmap);
+	put_dev_pagemap(pgmap);
 	return 1;
 }
 
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-gup-remove-set-but-unused-local-variable-major.patch
mm-gup-remove-unneed-local-variable-orig_refs.patch
mm-gup-remove-useless-bug_on-in-__get_user_pages.patch
mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge.patch
mm-gup-use-helper-page_aligned-in-populate_vma_page_range.patch
mm-vmscan-remove-the-pagedirty-check-after-madv_free-pages-are-page_ref_freezed.patch
mm-vmscan-remove-misleading-setting-to-sc-priority.patch
mm-vmscan-remove-unneeded-return-value-of-kswapd_run.patch
mm-vmscan-add-else-to-remove-check_pending-label.patch
mm-vmstat-correct-some-wrong-comments.patch
mm-vmstat-simplify-the-array-size-calculation.patch
mm-vmstat-remove-unneeded-return-value.patch
mm-zsmallocc-close-race-window-between-zs_pool_dec_isolated-and-zs_unregister_migration.patch
mm-zsmallocc-combine-two-atomic-ops-in-zs_pool_dec_isolated.patch