linux-kernel - [RFC v3 4/4] mm/debug: use %pGt to print page_type in dump

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Date:   Sun, 18 Dec 2022 19:19:01 +0900
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>
Cc:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>, Joe Perches <joe@...ches.com>,
        Petr Mladek <pmladek@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Matthew WilCox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [RFC v3 4/4] mm/debug: use %pGt to print page_type in dump_page()

Some page flags are stored in page_type rather than flags field.
Use newly introduced page type %pGt in dump_page().

Below are some examples:

page:00000000e47d45a7 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10175e
flags: 0x200000000000000(node=0|zone=2)
page_type: 0xffffffff()
raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: just after alloc_pages()

page:00000000e47d45a7 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10175e
flags: 0x200000000000000(node=0|zone=2)
page_type: 0xffefffff(slab)
raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffefffff 0000000000000000
page dumped because: page with PG_slab set

page:00000000e47d45a7 refcount:1 mapcount:2 mapping:0000000000000000 index:0x0 pfn:0x10175e
flags: 0x200000000000000(node=0|zone=2)
page_type: 0x1()
raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 0000000100000001 0000000000000000
page dumped because: page with _mapcount == 1

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
---
 mm/debug.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/debug.c b/mm/debug.c
index 5ce6b359004a..d6a0eb0a9bb8 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -120,6 +120,8 @@ static void __dump_page(struct page *page)
 
 	pr_warn("%sflags: %pGp%s\n", type, &head->flags,
 		page_cma ? " CMA" : "");
+	pr_warn("page_type: %pGt\n", &head->page_type);
+
 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), page,
 			sizeof(struct page), false);
-- 
2.32.0