mm, oom_reaper: do not mmput synchronously from the oom reaper context

[cascardo/linux.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 3e84515..8fbed71 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -699,6 +699,26 @@ void __mmdrop(struct mm_struct *mm)
 }
 EXPORT_SYMBOL_GPL(__mmdrop);
 
+static inline void __mmput(struct mm_struct *mm)
+{
+       VM_BUG_ON(atomic_read(&mm->mm_users));
+
+       uprobe_clear_state(mm);
+       exit_aio(mm);
+       ksm_exit(mm);
+       khugepaged_exit(mm); /* must run before exit_mmap */
+       exit_mmap(mm);
+       set_mm_exe_file(mm, NULL);
+       if (!list_empty(&mm->mmlist)) {
+               spin_lock(&mmlist_lock);
+               list_del(&mm->mmlist);
+               spin_unlock(&mmlist_lock);
+       }
+       if (mm->binfmt)
+               module_put(mm->binfmt->module);
+       mmdrop(mm);
+}
+
 /*
  * Decrement the use count and release all resources for an mm.
  */
@@ -706,24 +726,24 @@ void mmput(struct mm_struct *mm)
 {
        might_sleep();
 
+       if (atomic_dec_and_test(&mm->mm_users))
+               __mmput(mm);
+}
+EXPORT_SYMBOL_GPL(mmput);
+
+static void mmput_async_fn(struct work_struct *work)
+{
+       struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
+       __mmput(mm);
+}
+
+void mmput_async(struct mm_struct *mm)
+{
        if (atomic_dec_and_test(&mm->mm_users)) {
-               uprobe_clear_state(mm);
-               exit_aio(mm);
-               ksm_exit(mm);
-               khugepaged_exit(mm); /* must run before exit_mmap */
-               exit_mmap(mm);
-               set_mm_exe_file(mm, NULL);
-               if (!list_empty(&mm->mmlist)) {
-                       spin_lock(&mmlist_lock);
-                       list_del(&mm->mmlist);
-                       spin_unlock(&mmlist_lock);
-               }
-               if (mm->binfmt)
-                       module_put(mm->binfmt->module);
-               mmdrop(mm);
+               INIT_WORK(&mm->async_put_work, mmput_async_fn);
+               schedule_work(&mm->async_put_work);
        }
 }
-EXPORT_SYMBOL_GPL(mmput);
 
 /**
  * set_mm_exe_file - change a reference to the mm's executable file