From d7b236e10cedd95373a79fd53b7e9c105bea4f08 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Wed, 15 Nov 2017 17:33:22 -0800
Subject: [PATCH] mm: drop migrate type checks from has_unmovable_pages
Git-commit: d7b236e10cedd95373a79fd53b7e9c105bea4f08
Patch-mainline: v4.15-rc1
References: bnc#1074195
Michael has noticed that the memory offline tries to migrate kernel code
pages when doing
echo 0 > /sys/devices/system/memory/memory0/online
The current implementation will fail the operation after several failed
page migration attempts but we shouldn't even attempt to migrate that
memory and fail right away because this memory is clearly not
migrateable. This will become a real problem when we drop the retry
loop counter resp. timeout.
The real problem is in has_unmovable_pages in fact. We should fail if
there are any non migrateable pages in the area. In orther to guarantee
that remove the migrate type checks because MIGRATE_MOVABLE is not
guaranteed to contain only migrateable pages. It is merely a heuristic.
Similarly MIGRATE_CMA does guarantee that the page allocator doesn't
allocate any non-migrateable pages from the block but CMA allocations
themselves are unlikely to migrateable. Therefore remove both checks.
[akpm@linux-foundation.org: remove unused local `mt']
Link: http://lkml.kernel.org/r/20171013120013.698-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ran Wang <ran.wang_1@nxp.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/page_alloc.c | 4 ----
1 file changed, 4 deletions(-)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7334,7 +7334,6 @@ bool has_unmovable_pages(struct zone *zo
bool skip_hwpoisoned_pages)
{
unsigned long pfn, iter, found;
- int mt;
/*
* For avoiding noise data, lru_add_drain_all() should be called
@@ -7342,9 +7341,6 @@ bool has_unmovable_pages(struct zone *zo
*/
if (zone_idx(zone) == ZONE_MOVABLE)
return false;
- mt = get_pageblock_migratetype(page);
- if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
- return false;
pfn = page_to_pfn(page);
for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {