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| author |   Gavin Shan <gshan@redhat.com> | 2025-03-21 22:02:21 +1000 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2025-05-11 17:48:17 -0700 |
| commit | 979f3ef0f798d9b4fda4806d37fb1a264fc38566 (patch) | |
| tree | 7e1d7c1224d14b4d67bcc3770825e3be612077af | |
| parent | selftests/mm: add PAGEMAP_SCAN guard region test (diff) | |
| download | wireguard-linux-979f3ef0f798d9b4fda4806d37fb1a264fc38566.tar.xz wireguard-linux-979f3ef0f798d9b4fda4806d37fb1a264fc38566.zip | |
mm: fix parameter passed to page_mapcount_is_type()
Patch series "Fix parameter passed to page_mapcount_is_type()", v2.
Found by code inspection. There are two places where the parameter passed
to page_mapcount_is_type() is (page->_mapcount), which is incorrect since
it should be one more than the value, as explained in the comments to
page_mapcount_is_type(): (a) page_has_type() in page-flags.h (b)
__dump_folio() in mm/debug.c
PATCH[1] fixes the parameter for (a)
PATCH[2] fixes the parameter for (b)
Note that the issue doesn't cause any visible impacts due to the safety
gap introduced by PGTY_mapcount_underflow limit. So the tag 'Cc:
stable@vger.kernel.org' isn't needed.
This patch (of 2):
As the comments of page_mapcount_is_type() indicate, the parameter passed
to the function should be one more than page->_mapcount. However,
page->_mapcount (equivalent to page->page_type) is passed to the function
by commit 4ffca5a96678 ("mm: support only one page_type per page")
page_type_has_type() is replaced by page_mapcount_is_type(), but the
parameter isn't adjusted.
Fix it by replacing page_mapcount_is_type() with page_type_has_type() in
page_has_type(). Note that the issue doesn't cause any visible impacts
due to the safety gap introduced by PGTY_mapcount_underflow limit.
Link: https://lkml.kernel.org/r/20250321120222.1456770-1-gshan@redhat.com
Link: https://lkml.kernel.org/r/20250321120222.1456770-2-gshan@redhat.com
Fixes: 4ffca5a96678 ("mm: support only one page_type per page")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: gehao <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/page-flags.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index e6a21b62dcce..d3909cb1e576 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -982,7 +982,7 @@ static inline bool page_mapcount_is_type(unsigned int mapcount) static inline bool page_has_type(const struct page *page) { - return page_mapcount_is_type(data_race(page->page_type)); + return page_type_has_type(data_race(page->page_type)); } #define FOLIO_TYPE_OPS(lname, fname) \ |