powerpc/perf: fix imc allocation failure handling

The alloc_pages_node return value should be tested for failure
before being passed to page_address.
Tested-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190724084638.24982-3-npiggin@gmail.com

arch/powerpc/perf/imc-pmu.c

@@ -577,6 +577,7 @@ static int core_imc_mem_init(int cpu, int size)
 {
 	int nid, rc = 0, core_id = (cpu / threads_per_core);
 	struct imc_mem_info *mem_info;
+	struct page *page;
 
 	/*
 	 * alloc_pages_node() will allocate memory for core in the
@@ -587,11 +588,12 @@ static int core_imc_mem_init(int cpu, int size)
 	mem_info->id = core_id;
 
 	/* We need only vbase for core counters */
-	mem_info->vbase = page_address(alloc_pages_node(nid,
+	page = alloc_pages_node(nid,
 				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
-					  __GFP_NOWARN, get_order(size)));
-	if (!mem_info->vbase)
+				__GFP_NOWARN, get_order(size));
+	if (!page)
 		return -ENOMEM;
+	mem_info->vbase = page_address(page);
 
 	/* Init the mutex */
 	core_imc_refc[core_id].id = core_id;
@@ -849,15 +851,17 @@ static int thread_imc_mem_alloc(int cpu_id, int size)
 	int nid = cpu_to_node(cpu_id);
 
 	if (!local_mem) {
+		struct page *page;
 		/*
 		 * This case could happen only once at start, since we dont
 		 * free the memory in cpu offline path.
 		 */
-		local_mem = page_address(alloc_pages_node(nid,
+		page = alloc_pages_node(nid,
 				  GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
-				  __GFP_NOWARN, get_order(size)));
-		if (!local_mem)
+				  __GFP_NOWARN, get_order(size));
+		if (!page)
 			return -ENOMEM;
+		local_mem = page_address(page);
 
 		per_cpu(thread_imc_mem, cpu_id) = local_mem;
 	}
@@ -1095,11 +1099,14 @@ static int trace_imc_mem_alloc(int cpu_id, int size)
 	int core_id = (cpu_id / threads_per_core);
 
 	if (!local_mem) {
-		local_mem = page_address(alloc_pages_node(phys_id,
+		struct page *page;
+
+		page = alloc_pages_node(phys_id,
 				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
-					__GFP_NOWARN, get_order(size)));
-		if (!local_mem)
+				__GFP_NOWARN, get_order(size));
+		if (!page)
 			return -ENOMEM;
+		local_mem = page_address(page);
 		per_cpu(trace_imc_mem, cpu_id) = local_mem;
 
 		/* Initialise the counters for trace mode */