linux-kernel - [PATCH v2 8/8] kernel/fork: Use IS_ENABLED() in account_kernel

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Date:   Thu, 17 Feb 2022 11:24:06 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org
Cc:     Andy Lutomirski <luto@...nel.org>, Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v2 8/8] kernel/fork: Use IS_ENABLED() in account_kernel_stack().

Not strickly needed but checking CONFIG_VMAP_STACK instead of
task_stack_vm_area()' result allows the compiler the remove the else
path in the CONFIG_VMAP_STACK case where the pointer can't be NULL.

Check for CONFIG_VMAP_STACK in order to use the proper path.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/fork.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index aa17ed2a2afc7..4c97e0b5fb62a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -485,16 +485,16 @@ void vm_area_free(struct vm_area_struct *vma)
 
 static void account_kernel_stack(struct task_struct *tsk, int account)
 {
-	void *stack = task_stack_page(tsk);
-	struct vm_struct *vm = task_stack_vm_area(tsk);
-
-	if (vm) {
+	if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+		struct vm_struct *vm = task_stack_vm_area(tsk);
 		int i;
 
 		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
 			mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
 					      account * (PAGE_SIZE / 1024));
 	} else {
+		void *stack = task_stack_page(tsk);
+
 		/* All stack pages are in the same node. */
 		mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
 				      account * (THREAD_SIZE / 1024));
-- 
2.34.1