Re: [PATCH][RFT](2) minimal rmap for 2.5 - akpm tested

Linus Torvalds (torvalds@transmeta.com)
Sat, 6 Jul 2002 12:06:55 -0700 (PDT)


On Fri, 5 Jul 2002, Andrew Morton wrote:
>
> The box died, but not due to rmap. We have a lock ranking
> bug:
>
> do_exit
> ->mmput
> ->exit_mmap page_table_lock
> ->removed_shared_vm_struct
> ->lock_vma_mappings i_shared_lock

I _think_ we should just move the remove_shared_vm_struct() down into the
case where we're closing the mapping, ie something like the appended.

That way we _only_ do the actual page table stuff under the page table
lock, and do all the generic VM/FS stuff outside the lock.

Comments?

Linus

-------------------------------
--- 1.34/mm/mmap.c Thu Jun 27 00:35:55 2002
+++ edited/mm/mmap.c Sat Jul 6 12:06:02 2002
@@ -1121,7 +1121,6 @@
unsigned long end = mpnt->vm_end;

mm->map_count--;
- remove_shared_vm_struct(mpnt);
unmap_page_range(tlb, mpnt, start, end);
mpnt = mpnt->vm_next;
}
@@ -1148,6 +1147,7 @@
*/
while (mpnt) {
struct vm_area_struct * next = mpnt->vm_next;
+ remove_shared_vm_struct(mpnt);
if (mpnt->vm_ops) {
if (mpnt->vm_ops->close)
mpnt->vm_ops->close(mpnt);

-
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