From 74033a798f5a5db368126ee6f690111cf019bf7a Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@suse.de>
Date: Tue, 30 Jun 2015 14:57:23 -0700
Subject: [PATCH] mm: meminit: remove mminit_verify_page_links

mminit_verify_page_links() is an extremely paranoid check that was
introduced when memory initialisation was being heavily reworked.
Profiles indicated that up to 10% of parallel memory initialisation was
spent on checking this for every page.  The cost could be reduced but in
practice this check only found problems very early during the
initialisation rewrite and has found nothing since.  This patch removes an
expensive unnecessary check.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/internal.h   | 8 --------
 mm/mm_init.c    | 8 --------
 mm/page_alloc.c | 1 -
 3 files changed, 17 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 71d160437205..a48cbefde8ca 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -362,10 +362,7 @@ do { \
 } while (0)
 
 extern void mminit_verify_pageflags_layout(void);
-extern void mminit_verify_page_links(struct page *page,
-		enum zone_type zone, unsigned long nid, unsigned long pfn);
 extern void mminit_verify_zonelist(void);
-
 #else
 
 static inline void mminit_dprintk(enum mminit_level level,
@@ -377,11 +374,6 @@ static inline void mminit_verify_pageflags_layout(void)
 {
 }
 
-static inline void mminit_verify_page_links(struct page *page,
-		enum zone_type zone, unsigned long nid, unsigned long pfn)
-{
-}
-
 static inline void mminit_verify_zonelist(void)
 {
 }
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 28fbf87b20aa..fdadf918de76 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -131,14 +131,6 @@ void __init mminit_verify_pageflags_layout(void)
 	BUG_ON(or_mask != add_mask);
 }
 
-void __meminit mminit_verify_page_links(struct page *page, enum zone_type zone,
-			unsigned long nid, unsigned long pfn)
-{
-	BUG_ON(page_to_nid(page) != nid);
-	BUG_ON(page_zonenum(page) != zone);
-	BUG_ON(page_to_pfn(page) != pfn);
-}
-
 static __init int set_mminit_loglevel(char *str)
 {
 	get_option(&str, &mminit_loglevel);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f1f455a69cef..5a38e39b30d1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -839,7 +839,6 @@ static void __meminit __init_single_page(struct page *page, unsigned long pfn,
 				unsigned long zone, int nid)
 {
 	set_page_links(page, zone, nid, pfn);
-	mminit_verify_page_links(page, zone, nid, pfn);
 	init_page_count(page);
 	page_mapcount_reset(page);
 	page_cpupid_reset_last(page);