diff options
| author | Gavin Shan <gshan@redhat.com> | 2025-03-21 22:02:22 +1000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-05-11 17:48:17 -0700 |
| commit | 79049bb48a76333646d076e29d4f99fedefdaf0d (patch) | |
| tree | 8dd6272a32e4908a875dab68a053e6d5c3213c0a | |
| parent | 979f3ef0f798d9b4fda4806d37fb1a264fc38566 (diff) | |
mm/debug: fix parameter passed to page_mapcount_is_type()
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 is passed to the function by commit 4ffca5a96678 ("mm:
support only one page_type per page") where page_type_has_type() is
replaced by page_mapcount_is_type(), but the parameter isn't adjusted.
Fix the parameter for page_mapcount_is_type() to be (page->__mapcount +
1). Note that the issue doesn't cause any visible impacts due to the
safety gap introduced by PGTY_mapcount_underflow limit.
[akpm@linux-foundation.org: simplify __dump_folio(), per David]
Link: https://lkml.kernel.org/r/20250321120222.1456770-3-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-- | mm/debug.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/debug.c b/mm/debug.c index db83e381a8ae..907382257062 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -71,10 +71,12 @@ static void __dump_folio(struct folio *folio, struct page *page, unsigned long pfn, unsigned long idx) { struct address_space *mapping = folio_mapping(folio); - int mapcount = atomic_read(&page->_mapcount); + int mapcount = atomic_read(&page->_mapcount) + 1; char *type = ""; - mapcount = page_mapcount_is_type(mapcount) ? 0 : mapcount + 1; + if (page_mapcount_is_type(mapcount)) + mapcount = 0; + pr_warn("page: refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n", folio_ref_count(folio), mapcount, mapping, folio->index + idx, pfn); |