linux-kernel - [PATCH v2 3/3] mm, debug: move bad flags printing to bad

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Date:	Fri,  4 Dec 2015 16:16:35 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Minchan Kim <minchan@...nel.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...e.cz>,
	Vlastimil Babka <vbabka@...e.cz>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH v2 3/3] mm, debug: move bad flags printing to bad_page()

Since bad_page() is the only user of the badflags parameter of
dump_page_badflags(), we can move the code to bad_page() and simplify a bit.

The dump_page_badflags() function is renamed to __dump_page() and can still be
called separately from dump_page() for temporary debug prints where page_owner
info is not desired.

The only user-visible change is that page->mem_cgroup is printed before the bad
flags.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Sasha Levin <sasha.levin@...cle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Michal Hocko <mhocko@...e.cz>
---
 include/linux/mmdebug.h |  3 +--
 mm/debug.c              | 14 +++-----------
 mm/page_alloc.c         | 10 +++++++---
 3 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 2c8286cf162e..9b0dc2161f7a 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -14,8 +14,7 @@ extern const struct trace_print_flags vmaflag_names[];
 extern const struct trace_print_flags gfpflag_names[];
 
 extern void dump_page(struct page *page, const char *reason);
-extern void dump_page_badflags(struct page *page, const char *reason,
-			       unsigned long badflags);
+extern void __dump_page(struct page *page, const char *reason);
 void dump_vma(const struct vm_area_struct *vma);
 void dump_mm(const struct mm_struct *mm);
 
diff --git a/mm/debug.c b/mm/debug.c
index c42bb4c13c2d..d36aa66e9779 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -109,25 +109,17 @@ const struct trace_print_flags gfpflag_names[] = {
 	{0, NULL},
 };
 
-void dump_page_badflags(struct page *page, const char *reason,
-		unsigned long badflags)
+void __dump_page(struct page *page, const char *reason)
 {
-	unsigned long printflags = page->flags;
-
 	pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
 		  page, atomic_read(&page->_count), page_mapcount(page),
 		  page->mapping, page->index);
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
 
-	pr_emerg("flags: %#lx(%pgp)\n", printflags, &printflags);
+	pr_emerg("flags: %#lx(%pgp)\n", page->flags, &page->flags);
 
 	if (reason)
 		pr_alert("page dumped because: %s\n", reason);
-	if (page->flags & badflags) {
-		printflags = page->flags & badflags;
-		pr_alert("bad because of flags: %#lx(%pgp)\n", printflags,
-								&printflags);
-	}
 #ifdef CONFIG_MEMCG
 	if (page->mem_cgroup)
 		pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
@@ -136,7 +128,7 @@ void dump_page_badflags(struct page *page, const char *reason,
 
 void dump_page(struct page *page, const char *reason)
 {
-	dump_page_badflags(page, reason, 0);
+	__dump_page(page, reason);
 	dump_page_owner(page);
 }
 EXPORT_SYMBOL(dump_page);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bd94c7465dea..2388496a7c6c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -435,7 +435,7 @@ static void bad_page(struct page *page, const char *reason,
 			goto out;
 		}
 		if (nr_unshown) {
-			printk(KERN_ALERT
+			pr_alert(
 			      "BUG: Bad page state: %lu messages suppressed\n",
 				nr_unshown);
 			nr_unshown = 0;
@@ -445,9 +445,13 @@ static void bad_page(struct page *page, const char *reason,
 	if (nr_shown++ == 0)
 		resume = jiffies + 60 * HZ;
 
-	printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
+	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
 		current->comm, page_to_pfn(page));
-	dump_page_badflags(page, reason, bad_flags);
+	__dump_page(page, reason);
+	bad_flags &= page->flags;
+	if (bad_flags)
+		pr_alert("bad because of flags: %#lx(%pgp)\n",
+						bad_flags, &bad_flags);
 	dump_page_owner(page);
 
 	print_modules();
-- 
2.6.3

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