On 04/28/2010 02:03 PM, Andrea Arcangeli wrote:
On Wed, Apr 28, 2010 at 01:47:19PM -0400, Rik van Riel wrote:
static inline void anon_vma_unlock(struct vm_area_struct *vma)
never mind as this is RFC, lock is clear enough
@@ -1762,7 +1760,8 @@ static int expand_downwards(struct vm_area_struct *vma,
if (error)
return error;
- anon_vma_lock(vma);
+ spin_lock(&mm->page_table_lock);
+ anon_vma_lock(vma,&mm->page_table_lock);
This will cause a lock inversion (page_table_lock can only be taken
after the anon_vma lock). I don't immediately see why the
page_table_lock here though?
We need to safely walk the vma->anon_vma_chain /
anon_vma_chain->same_vma list.
So much for using the mmap_sem for read + the
page_table_lock to lock the anon_vma_chain list.
We'll need a new lock somewhere, probably in the
mm_struct since one per process seems plenty.
I'll add that in the next version of the patch.
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