2.4.0

 kernel

diff -u --recursive --new-file v2.4.0-prerelease/linux/kernel/fork.c linux/kernel/fork.c
--- v2.4.0-prerelease/linux/kernel/fork.c   Mon Jan  1 09:38:36 2001
+++ linux/kernel/fork.c   Wed Jan  3 20:45:26 2001
@@ -192,6 +192,8 @@
    return retval;
 }
 
+spinlock_t mmlist_lock __cacheline_aligned = SPIN_LOCK_UNLOCKED;
+
 #define allocate_mm()   (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
 #define free_mm(mm)   (kmem_cache_free(mm_cachep, (mm)))
 
@@ -242,7 +244,9 @@
  */
 void mmput(struct mm_struct *mm)
 {
-   if (atomic_dec_and_test(&mm->mm_users)) {
+   if (atomic_dec_and_lock(&mm->mm_users, &mmlist_lock)) {
+      list_del(&mm->mmlist);
+      spin_unlock(&mmlist_lock);
       exit_mmap(mm);
       mmdrop(mm);
    }
@@ -272,9 +276,9 @@
    }
 }
 
-static inline int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
+static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
 {
-   struct mm_struct * mm;
+   struct mm_struct * mm, *oldmm;
    int retval;
 
    tsk->min_flt = tsk->maj_flt = 0;
@@ -289,12 +293,13 @@
     *
     * We need to steal a active VM for that..
     */
-   mm = current->mm;
-   if (!mm)
+   oldmm = current->mm;
+   if (!oldmm)
       return 0;
 
    if (clone_flags & CLONE_VM) {
-      atomic_inc(&mm->mm_users);
+      atomic_inc(&oldmm->mm_users);
+      mm = oldmm;
       goto good_mm;
    }
 
@@ -304,16 +309,25 @@
       goto fail_nomem;
 
    /* Copy the current MM stuff.. */
-   memcpy(mm, current->mm, sizeof(*mm));
+   memcpy(mm, oldmm, sizeof(*mm));
    if (!mm_init(mm))
       goto fail_nomem;
 
-   tsk->mm = mm;
-   tsk->active_mm = mm;
-
-   down(¤t->mm->mmap_sem);
+   down(&oldmm->mmap_sem);
    retval = dup_mmap(mm);
-   up(¤t->mm->mmap_sem);
+   up(&oldmm->mmap_sem);
+
+   /*
+    * Add it to the mmlist after the parent.
+    *
+    * Doing it this way means that we can order
+    * the list, and fork() won't mess up the
+    * ordering significantly.
+    */
+   spin_lock(&mmlist_lock);
+   list_add(&mm->mmlist, &oldmm->mmlist);
+   spin_unlock(&mmlist_lock);
+
    if (retval)
       goto free_pt;