On Mon, Nov 5, 2012 at 5:41 AM, Michel Lespinasse <walken@xxxxxxxxxx> wrote: > On Sun, Nov 4, 2012 at 8:44 PM, Michel Lespinasse <walken@xxxxxxxxxx> wrote: >> On Sun, Nov 4, 2012 at 8:14 PM, Bob Liu <lliubbo@xxxxxxxxx> wrote: >>> Hmm, I attached a simple fix patch. >> >> Reviewed-by: Michel Lespinasse <walken@xxxxxxxxxx> >> (also ran some tests with it, but I could never reproduce the original >> issue anyway). > > Wait a minute, this is actually wrong. You need to call > vma_lock_anon_vma() / vma_unlock_anon_vma() to avoid the issue with > vma->anon_vma == NULL. > > I'll fix it and integrate it into my next patch series, which I intend > to send later today. (I am adding new code into validate_mm(), so that > it's easier to have it in the same patch series to avoid merge > conflicts) Hmmm, now I'm getting confused about anon_vma locking again :/ As Hugh privately remarked to me, the same_vma linked list is supposed to be protected by exclusive mmap_sem ownership, not by anon_vma lock. So now looking at it a bit more, I'm not sure what race we're preventing by taking the anon_vma lock in validate_mm() ??? -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>