linux-kernel - [PATCH v3 4/4] memory_hotplug: use pgdat_resize_lock() in __offline

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Message-Id: <1368486787-9511-5-git-send-email-cody@linux.vnet.ibm.com>
Date:	Mon, 13 May 2013 16:13:07 -0700
From:	Cody P Schafer <cody@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Rientjes <rientjes@...gle.com>,
	Linux MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cody P Schafer <cody@...ux.vnet.ibm.com>
Subject: [PATCH v3 4/4] memory_hotplug: use pgdat_resize_lock() in __offline_pages()

mmzone.h documents node_size_lock (which pgdat_resize_lock() locks) as
follows:

        * Must be held any time you expect node_start_pfn, node_present_pages
        * or node_spanned_pages stay constant.  [...]

So actually hold it when we update node_present_pages in __offline_pages().

Signed-off-by: Cody P Schafer <cody@...ux.vnet.ibm.com>
---
 mm/memory_hotplug.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0bdca10..b59a695 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1582,7 +1582,11 @@ repeat:
 	/* removal success */
 	zone->managed_pages -= offlined_pages;
 	zone->present_pages -= offlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
 	zone->zone_pgdat->node_present_pages -= offlined_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
 	totalram_pages -= offlined_pages;
 
 	init_per_zone_wmark_min();
-- 
1.8.2.2

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