fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK

memcg_charge_kernel_stack() is only used in the CONFIG_VMAP_STACK case.

Move memcg_charge_kernel_stack() into the CONFIG_VMAP_STACK block and
invoke it from within alloc_thread_stack_node().

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/20220217102406.3697941-6-bigeasy@linutronix.de

diff --git a/kernel/fork.c b/kernel/fork.c
index 875bd43..ac63e7f 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -211,6 +211,32 @@ static int free_vm_stack_cache(unsigned int cpu)
        return 0;
 }
 
+static int memcg_charge_kernel_stack(struct task_struct *tsk)
+{
+       struct vm_struct *vm = task_stack_vm_area(tsk);
+       int i;
+       int ret;
+
+       BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
+       BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
+
+       for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
+               ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
+               if (ret)
+                       goto err;
+       }
+       return 0;
+err:
+       /*
+        * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
+        * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
+        * ignore this page.
+        */
+       for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+               memcg_kmem_uncharge_page(vm->pages[i], 0);
+       return ret;
+}
+
 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
 {
        void *stack;
@@ -230,6 +256,11 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
                /* Clear stale pointers from reused stack. */
                memset(s->addr, 0, THREAD_SIZE);
 
+               if (memcg_charge_kernel_stack(tsk)) {
+                       vfree(s->addr);
+                       return -ENOMEM;
+               }
+
                tsk->stack_vm_area = s;
                tsk->stack = s->addr;
                return 0;
@@ -247,6 +278,11 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
                                     0, node, __builtin_return_address(0));
        if (!stack)
                return -ENOMEM;
+
+       if (memcg_charge_kernel_stack(tsk)) {
+               vfree(stack);
+               return -ENOMEM;
+       }
        /*
         * We can't call find_vm_area() in interrupt context, and
         * free_thread_stack() can be called in interrupt context,
@@ -418,36 +454,6 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
        }
 }
 
-static int memcg_charge_kernel_stack(struct task_struct *tsk)
-{
-#ifdef CONFIG_VMAP_STACK
-       struct vm_struct *vm = task_stack_vm_area(tsk);
-       int ret;
-
-       BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
-
-       if (vm) {
-               int i;
-
-               BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
-
-               for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
-                       /*
-                        * If memcg_kmem_charge_page() fails, page's
-                        * memory cgroup pointer is NULL, and
-                        * memcg_kmem_uncharge_page() in free_thread_stack()
-                        * will ignore this page.
-                        */
-                       ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
-                                                    0);
-                       if (ret)
-                               return ret;
-               }
-       }
-#endif
-       return 0;
-}
-
 static void release_task_stack(struct task_struct *tsk)
 {
        if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
@@ -909,9 +915,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
        if (err)
                goto free_tsk;
 
-       if (memcg_charge_kernel_stack(tsk))
-               goto free_stack;
-
 #ifdef CONFIG_THREAD_INFO_IN_TASK
        refcount_set(&tsk->stack_refcount, 1);
 #endif