On 05/06/2010 11:33 AM, Mel Gorman wrote:
@@ -1368,16 +1424,25 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
* are holding mmap_sem. Users without mmap_sem are required to
* take a reference count to prevent the anon_vma disappearing
*/
- anon_vma = page_anon_vma(page);
+ anon_vma = page_anon_vma_lock_root(page);
if (!anon_vma)
return ret;
- spin_lock(&anon_vma->lock);
list_for_each_entry(avc,&anon_vma->head, same_anon_vma) {
One conceptual problem here. By taking the oldest anon_vma,
instead of the anon_vma of the page, we may end up searching
way too many processes.
Eg. if the page is the page of a child process in a forking
server workload, the above code will end up searching the
parent and all of the siblings - even for a private page, in
the child process's private anon_vma.
For an Apache or Oracle system with 1000 clients (and child
processes), that could be quite a drag - searching 1000 times
as many processes as we should.
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