Messages in this thread | | | Date | Fri, 9 Apr 2010 12:32:30 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas of a mergeable VMA |
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On Fri, 9 Apr 2010, Borislav Petkov wrote: > > > > So what I _think_ will happen is that you'll be able to re-create the > > problem that started this all. But I'd like to verify that, just because > > I'm anal and I'd like these things to be tested independently. > > Heh, that was easy. Third hibernate cycle is a charm^Wboom :)
Ok, good to know that I'm still tracking ok on the issue.
> > So assuming that the original problem happens again, if you can then apply > > Rik's patch, but add a > > > > dst->anon_vma = src->anon_vma; > > > > to just before the success case (the "return 0") in anon_vma_clone(), > > that would be good. > > It looks like this way we mangle the anon_vma chains somehow. From > what I can see and if I'm not mistaken, we save the anon_vmas alright > but end up in what seems like an endless list_for_each_entry() > loop having grabbed anon_vma->lock in page_lock_anon_vma() and we > can't seem to yield it through page_unlock_anon_vma() at the end of > page_referenced_anon() so it has to be that code in between iterating > over each list entry...
Ok. So scratch Rik's patch. It doesn't work even with the anon_vma set up.
Rik? I think it's back to you. I'm not going to bother committing the change to the anon_vma locking unless you actually need the locking guarantees for anon_vma_prepare().
And I've got the feeling that the proper fix is in the vma_adjust() handling if your original idea was right.
Anybody?
We're at the point where I've already delayed -rc4 several days because it's pointless cutting it without fixing this. One option is to just say "f*ck it, we'll revert it all and try again later". But it feels so close..
Linus
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