On Wed, 12 May 2010 13:39:58 -0400 Rik van Riel <riel@xxxxxxxxxx> wrote: > Subject: track the root (oldest) anon_vma > > Track the root (oldest) anon_vma in each anon_vma tree. Because we only > take the lock on the root anon_vma, we cannot use the lock on higher-up > anon_vmas to lock anything. This makes it impossible to do an indirect > lookup of the root anon_vma, since the data structures could go away from > under us. > > However, a direct pointer is safe because the root anon_vma is always the > last one that gets freed on munmap or exit, by virtue of the same_vma list > order and unlink_anon_vmas walking the list forward. > > Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> I welcome this. Thank you! Reading 4/5, I felt I'm grad if you add a Documentation or very-precise-comment about the new anon_vma rules and the _meaning_ of anon_vma_root_lock. I cannot fully convice myself that I understand them all. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>