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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2024-03-21 17:24:46 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-04-26 06:56:00 +0300 |
| commit | 8f790d0c7cfed047a1f7aad3fcddd7a979bf7232 (patch) | |
| tree | 1b6edee98ae59cd707c735dc9182faf8c047a178 | |
| parent | 46df8e73a4a3f1445f2a8429111e72ede1f4d291 (diff) | |
| download | linux-8f790d0c7cfed047a1f7aad3fcddd7a979bf7232.tar.xz | |
mm: improve dumping of mapcount and page_type
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>
| -rw-r--r-- | mm/debug.c | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/mm/debug.c b/mm/debug.c index c1c1a6a484e4..e8a96b8b7197 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, |