| Message ID | 20240321142448.1645400-9-willy@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Various significant MM patches | expand |
On 3/21/24 15:24, Matthew Wilcox (Oracle) wrote: > 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. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/debug.c | 19 ++++++++----------- > 1 file 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,
On 21.03.24 15:24, Matthew Wilcox (Oracle) wrote: > 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. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- Reviewed-by: David Hildenbrand <david@redhat.com>
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,
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- mm/debug.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)