On Mon, May 03, 2010 at 02:40:44AM +0900, Minchan Kim wrote: > On Fri, Apr 30, 2010 at 1:21 AM, Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > > Hi Mel, > > > > did you see my proposed fix? I'm running with it applied, I'd be > > interested if you can test it. Surely it will also work for new > > anon-vma code in upstream, because at that point there's just 1 > > anon-vma and nothing else attached to the vma. > > > > http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git;a=commit;h=6efa1dfa5152ef8d7f26beb188d6877525a9dd03 > > > > I think it's wrong to try to handle the race in rmap walk by making > > magic checks on vm_flags VM_GROWSDOWN|GROWSUP and > > vma->vm_mm->map_count == 1, when we can fix it fully and simply in > > exec.c by indexing two vmas in the same anon-vma with a different > > vm_start so the pages will be found at all times by the rmap_walk. > > > > I like this approach than exclude temporal stack while migration. > > If we look it through viewpoint of performance, Mel and Kame's one > look good and simple. But If I look it through viewpoint of > correctness, Andrea's one looks good. > I mean Mel's approach is that problem is here but let us solve it with > there. it makes dependency between here and there. And In future, if > temporal stack and rmap code might be problem, we also should solve it > in there. :) That explains exactly why I wanted to solve it locally to exec.c and by using the same method of mremap. And it fixes all users not just migrate (split_huge_page may also need it in the future if we ever allow the user stack to be born huge instead of growing huge with khugepaged if needed). -- 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>