fork: free vmapped stacks in cache when cpus are offline

[platform/kernel/linux-starfive.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index dd5a371..55e325f 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -179,6 +179,24 @@ void __weak arch_release_thread_stack(unsigned long *stack)
  */
 #define NR_CACHED_STACKS 2
 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
+
+static int free_vm_stack_cache(unsigned int cpu)
+{
+       struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
+       int i;
+
+       for (i = 0; i < NR_CACHED_STACKS; i++) {
+               struct vm_struct *vm_stack = cached_vm_stacks[i];
+
+               if (!vm_stack)
+                       continue;
+
+               vfree(vm_stack->addr);
+               cached_vm_stacks[i] = NULL;
+       }
+
+       return 0;
+}
 #endif
 
 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
@@ -467,6 +485,11 @@ void __init fork_init(void)
        for (i = 0; i < UCOUNT_COUNTS; i++) {
                init_user_ns.ucount_max[i] = max_threads/2;
        }
+
+#ifdef CONFIG_VMAP_STACK
+       cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
+                         NULL, free_vm_stack_cache);
+#endif
 }
 
 int __weak arch_dup_task_struct(struct task_struct *dst,