[patch 045/108] mm: drop page_initialized check from get_nid_for_pfn

[patch 045/108] mm: drop page_initialized check from get_nid_for_pfn

[akpm]

From: Michal Hocko <mhocko@suse.com>
Subject: mm: drop page_initialized check from get_nid_for_pfn

c04fc586c1a4 ("mm: show node to memory section relationship with symlinks
in sysfs") has added means to export memblock<->node association into the
sysfs.  It has also introduced get_nid_for_pfn which is a rather confusing
counterpart of pfn_to_nid which checks also whether the pfn page is
already initialized (page_initialized).  This is done by checking
page::lru != NULL which doesn't make any sense at all.  Nothing in this
path really relies on the lru list being used or initialized.  Just remove
it because this will become a problem with later patches.

Thanks to Reza Arbab for testing which revealed this to be a problem
(http://lkml.kernel.org/r/20170403202337.GA12482@dhcp22.suse.cz)

Link: http://lkml.kernel.org/r/20170515085827.16474-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/base/node.c |    7 -------
 1 file changed, 7 deletions(-)

diff -puN drivers/base/node.c~mm-drop-page_initialized-check-from-get_nid_for_pfn drivers/base/node.c
--- a/drivers/base/node.c~mm-drop-page_initialized-check-from-get_nid_for_pfn
+++ a/drivers/base/node.c
@@ -368,21 +368,14 @@ int unregister_cpu_under_node(unsigned i
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
-#define page_initialized(page)  (page->lru.next)
-
 static int __ref get_nid_for_pfn(unsigned long pfn)
 {
-	struct page *page;