[PATCH v1 17/18] mm/debug: print only page mapcount (excluding folio entire mapcount) in __dump_folio()

David Hildenbrand
2024-04-09T19:27:00Z

Let's simplify and only print the page mapcount: we already print the
large folio mapcount and the entire folio mapcount for large folios
separately; that should be sufficient to figure out what's happening.

While at it, print the page mapcount also if it had an underflow,
filtering out only typed pages.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/debug.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/mm/debug.c b/mm/debug.c
index d064db42af54..69e524c3e601 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -55,15 +55,10 @@ 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) + 1;
+ int mapcount = atomic_read(&page->_mapcount);
char *type = "";

- /* 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);
-
+ mapcount = page_type_has_type(mapcount) ? 0 : mapcount + 1;
pr_warn("page: refcount:%d mapcount:%d mapping:%p index:%#lx pfn:%#lx\n",
folio_ref_count(folio), mapcount, mapping,
folio->index + idx, pfn);
--
2.44.0