linux-kernel - [PATCH] memory-hotplug: don't BUG() in register_memory

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Date:	Fri, 18 Dec 2015 15:50:24 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tang Chen <tangchen@...fujitsu.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Xishi Qiu <qiuxishi@...wei.com>,
	Sheng Yong <shengyong1@...wei.com>,
	David Rientjes <rientjes@...gle.com>,
	Zhu Guihua <zhugh.fnst@...fujitsu.com>,
	Dan Williams <dan.j.williams@...el.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Igor Mammedov <imammedo@...hat.com>
Subject: [PATCH] memory-hotplug: don't BUG() in register_memory_resource()

Out of memory condition is not a bug and while we can't add new memory in
such case crashing the system seems wrong. Propagating the return value
from register_memory_resource() requires interface change.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Tang Chen <tangchen@...fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Xishi Qiu <qiuxishi@...wei.com>
Cc: Sheng Yong <shengyong1@...wei.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Zhu Guihua <zhugh.fnst@...fujitsu.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: David Vrabel <david.vrabel@...rix.com>
Cc: Igor Mammedov <imammedo@...hat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 mm/memory_hotplug.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 67d488a..9392f01 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -127,11 +127,13 @@ void mem_hotplug_done(void)
 }
 
 /* add this memory to iomem resource */
-static struct resource *register_memory_resource(u64 start, u64 size)
+static int register_memory_resource(u64 start, u64 size,
+				    struct resource **resource)
 {
 	struct resource *res;
 	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
-	BUG_ON(!res);
+	if (!res)
+		return -ENOMEM;
 
 	res->name = "System RAM";
 	res->start = start;
@@ -140,9 +142,10 @@ static struct resource *register_memory_resource(u64 start, u64 size)
 	if (request_resource(&iomem_resource, res) < 0) {
 		pr_debug("System RAM resource %pR cannot be added\n", res);
 		kfree(res);
-		res = NULL;
+		return -EEXIST;
 	}
-	return res;
+	*resource = res;
+	return 0;
 }
 
 static void release_memory_resource(struct resource *res)
@@ -1311,9 +1314,9 @@ int __ref add_memory(int nid, u64 start, u64 size)
 	struct resource *res;
 	int ret;
 
-	res = register_memory_resource(start, size);
-	if (!res)
-		return -EEXIST;
+	ret = register_memory_resource(start, size, &res);
+	if (ret)
+		return ret;
 
 	ret = add_memory_resource(nid, res);
 	if (ret < 0)
-- 
2.4.3

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