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@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220217102406.3697941-9-bigeasy@linutronix.de

diff --git a/kernel/fork.c b/kernel/fork.c
index 177bc64..1279b57 100644 (file)
--- 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));