linux-kernel - [PATCH v3] mm/debug: __dump

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Date:   Mon, 11 Nov 2019 17:26:08 -0800
From:   Ralph Campbell <rcampbell@...dia.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Ralph Campbell <rcampbell@...dia.com>
Subject: [PATCH v3] mm/debug: __dump_page() prints an extra line

When dumping struct page information, __dump_page() prints the page type
with a trailing blank followed by the page flags on a separate line:

anon
flags: 0x100000000090034(uptodate|lru|active|head|swapbacked)

It looks like the intent was to use pr_cont() for printing "flags:"
but pr_cont() usage is discouraged so fix this by extending the format
to include the flags into a single line:

anon flags: 0x100000000090034(uptodate|lru|active|head|swapbacked)

If the page is file backed, the name might be long so use two lines:

shmem_aops name:"dev/zero"
flags: 0x10000000008000c(uptodate|dirty|swapbacked)

Eliminate pr_conf() usage as well for appending compound_mapcount.

Signed-off-by: Ralph Campbell <rcampbell@...dia.com>
---
 mm/debug.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/mm/debug.c b/mm/debug.c
index 8345bb6e4769..772d4cf0691f 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -67,28 +67,31 @@ void __dump_page(struct page *page, const char *reason)
 	 */
 	mapcount = PageSlab(page) ? 0 : page_mapcount(page);
 
-	pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx",
-		  page, page_ref_count(page), mapcount,
-		  page->mapping, page_to_pgoff(page));
 	if (PageCompound(page))
-		pr_cont(" compound_mapcount: %d", compound_mapcount(page));
-	pr_cont("\n");
+		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px "
+			"index:%#lx compound_mapcount: %d\n",
+			page, page_ref_count(page), mapcount,
+			page->mapping, page_to_pgoff(page),
+			compound_mapcount(page));
+	else
+		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
+			page, page_ref_count(page), mapcount,
+			page->mapping, page_to_pgoff(page));
 	if (PageAnon(page))
-		pr_warn("anon ");
+		pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags);
 	else if (PageKsm(page))
-		pr_warn("ksm ");
+		pr_warn("ksm flags: %#lx(%pGp)\n", page->flags, &page->flags);
 	else if (mapping) {
-		pr_warn("%ps ", mapping->a_ops);
 		if (mapping->host && mapping->host->i_dentry.first) {
 			struct dentry *dentry;
 			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
-			pr_warn("name:\"%pd\" ", dentry);
-		}
+			pr_warn("%ps name:\"%pd\"\n", mapping->a_ops, dentry);
+		} else
+			pr_warn("%ps\n", mapping->a_ops);
+		pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
 	}
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 
-	pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
-
 hex_only:
 	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
 			sizeof(unsigned long), page,
-- 
2.20.1