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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 commit4ffca5a966("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:4ffca5a966("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>