On Fri, 18 Dec 2015 15:50:24 +0100 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
> 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.
>
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> +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;
> }
Was there a reason for overwriting the request_resource() return value?
Ordinarily it should be propagated back to callers.
Please review.
--- a/mm/memory_hotplug.c~memory-hotplug-dont-bug-in-register_memory_resource-fix
+++ a/mm/memory_hotplug.c
@@ -131,7 +131,9 @@ static int register_memory_resource(u64
struct resource **resource)
{
struct resource *res;
+ int ret = 0;
res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+
if (!res)
return -ENOMEM;
@@ -139,13 +141,14 @@ static int register_memory_resource(u64
res->start = start;
res->end = start + size - 1;
res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- if (request_resource(&iomem_resource, res) < 0) {
+ ret = request_resource(&iomem_resource, res);
+ if (ret < 0) {
pr_debug("System RAM resource %pR cannot be added\n", res);
kfree(res);
- return -EEXIST;
+ } else {
+ *resource = res;
}
- *resource = res;
- return 0;
+ return ret;
}
static void release_memory_resource(struct resource *res)
_
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