From: "Matthew Wilcox (Oracle)" willy@infradead.org
mainline inclusion from mainline-v6.10-rc1 commit 8f790d0c7cfed047a1f7aad3fcddd7a979bf7232 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IACHGW
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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For pages that have a page_type, set the mapcount to 0, which will reduce the confusion in people reading page dumps ("Why does this page have a mapcount of -128?"). Now that hugetlbfs is a page_type, read the entire_mapcount for any large folio; this is fine for all folios as no user reuses the entire_mapcount field.
For pages which do not have a page type, do not print it to reduce clutter.
Link: https://lkml.kernel.org/r/20240321142448.1645400-9-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Reviewed-by: David Hildenbrand david@redhat.com Acked-by: Vlastimil Babka vbabka@suse.cz Cc: Miaohe Lin linmiaohe@huawei.com Cc: Muchun Song muchun.song@linux.dev Cc: Oscar Salvador osalvador@suse.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- mm/debug.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/mm/debug.c b/mm/debug.c index 12fed592c955..0dd516a6640e 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -55,18 +55,14 @@ 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 = 0; + int mapcount = atomic_read(&page->_mapcount) + 1; char *type = "";
- /* - * page->_mapcount space in struct page is used by slab pages to - * encode own info, and we must avoid calling page_folio() again. - */ - if (!folio_test_slab(folio)) { - mapcount = atomic_read(&page->_mapcount) + 1; - if (folio_test_large(folio)) - mapcount += folio_entire_mapcount(folio); - } + /* Open-code page_mapcount() to avoid looking up a stale folio */ + if (mapcount < 0) + mapcount = 0; + if (folio_test_large(folio)) + mapcount += folio_entire_mapcount(folio);
pr_warn("page: refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n", folio_ref_count(folio), mapcount, mapping, @@ -99,7 +95,8 @@ static void __dump_folio(struct folio *folio, struct page *page, */ pr_warn("%sflags: %pGp%s\n", type, &folio->flags, is_migrate_cma_folio(folio, pfn) ? " CMA" : ""); - pr_warn("page_type: %pGt\n", &folio->page.page_type); + if (page_has_type(&folio->page)) + pr_warn("page_type: %pGt\n", &folio->page.page_type);
print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page,