[PATCHv2] CMA/HOTPLUG: clear buffer-head lru before page migration

[Gioh Kim <gioh.kim@lge.com>]

I removed checking migratetype of v1: https://lkml.org/lkml/2014/7/18/82.
Thanks a lot.


---------------------------- 8< ------------------------------
>From 95addf7f1644cde3a0944629ff5c6a8d6f43e5d6 Mon Sep 17 00:00:00 2001
From: Gioh Kim <gioh.kim@lge.com>
Date: Fri, 18 Jul 2014 13:40:01 +0900
Subject: [PATCH] CMA/HOTPLUG: clear buffer-head lru before page migration

The bh must be free to migrate a page at which bh is mapped.
The reference count of bh is increased when it is installed
into lru so that the bh of lru must be freed before migrating the page.

This frees every bh of lru. We could free only bh of migrating page.
But searching lru costs more than invalidating entire lru.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
---
 mm/page_alloc.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b99643d4..c00dedf 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6369,6 +6369,8 @@ int alloc_contig_range(unsigned long start, unsigned long end,
        if (ret)
                return ret;

+       invalidate_bh_lrus();
+
        ret = __alloc_contig_migrate_range(&cc, start, end);
        if (ret)
                goto done;
--
1.7.9.5