[tip: core/core] fork: Use IS_ENABLED() in account_kernel_stack()

[tip-bot2 for Sebastian Andrzej Siewior]

The following commit has been merged into the core/core branch of tip:

Commit-ID:     0ce055f85335e48bc571114d61a70ae217039362
Gitweb:        https://git.kernel.org/tip/0ce055f85335e48bc571114d61a70ae217039362
Author:        Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate:    Thu, 17 Feb 2022 11:24:06 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 22 Feb 2022 22:25:02 +01:00

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

---
 kernel/fork.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

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