linux-kernel - [PATCH mm-unstable v4 3/3] mm/debug: use %pGt to display page_type in dump

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Date:   Mon, 30 Jan 2023 13:25:14 +0900
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Joe Perches <joe@...ches.com>, Petr Mladek <pmladek@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Matthew WilCox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH mm-unstable v4 3/3] mm/debug: use %pGt to display 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:00000000da7184dd refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101cb3
flags: 0x2ffff0000000000(node=0|zone=2|lastcpupid=0xffff)
page_type: 0xffffffff()
raw: 02ffff0000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: newly allocated page

page:00000000da7184dd refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x101cb3
flags: 0x2ffff0000000000(node=0|zone=2|lastcpupid=0xffff)
page_type: 0xffffff7f(buddy)
raw: 02ffff0000000000 ffff88813fff8e80 ffff88813fff8e80 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffff7f 0000000000000000
page dumped because: freed page

page:0000000042202316 refcount:3 mapcount:2 mapping:0000000000000000 index:0x7f634722a pfn:0x11994e
memcg:ffff888100135000
anon flags: 0x2ffff0000080024(uptodate|active|swapbacked|node=0|zone=2|lastcpupid=0xffff)
page_type: 0x1()
raw: 02ffff0000080024 0000000000000000 dead000000000122 ffff8881193398f1
raw: 00000007f634722a 0000000000000000 0000000300000001 ffff888100135000
page dumped because: user-mapped page

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 01cf0435723b..c7b228097bd9 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);
-- 
2.39.1