On Fri, Dec 07, 2012 at 04:49:56PM -0800, John Stultz wrote: > On 12/04/2012 08:18 PM, Minchan Kim wrote: > >On Tue, Dec 04, 2012 at 11:13:40AM -0800, John Stultz wrote: > >>I don't think the problem is when vmas being marked VM_VOLATILE are > >>being merged, its that when we mark the vma as *non-volatile*, and > >>remove the VM_VOLATILE flag we merge the non-volatile vmas with > >>neighboring vmas. So preserving the purged flag during that merge is > >>important. Again, the example I used to trigger this was an > >>alternating pattern of volatile and non volatile vmas, then marking > >>the entire range non-volatile (though sometimes in two overlapping > >>passes). > >Understood. Thanks. > >Below patch solves your problems? It's simple than yours. > > Yea, this is nicer then my fix. > Although I still need the purged handling in the vma merge code for > me to see the behavior I expect in my tests. > > I've integrated your patch and repushed my queue here: > http://git.linaro.org/gitweb?p=people/jstultz/android-dev.git;a=shortlog;h=refs/heads/dev/minchan-anonvol > > git://git.linaro.org/people/jstultz/android-dev.git dev/minchan-anonvol > > >Anyway, both yours and mine are not right fix. > >As I mentioned, locking scheme is broken. > >We need anon_vma_lock to handle purged and we should consider fork > >case, too. > Hrm. I'm sure you're right, as I've not yet fully grasped all the > locking rules here. Could you clarify how it is broken? And why is > the anon_vma_lock needed to manage the purged state that is part of > the vma itself? If you don't hold anon->lock, merge/split/fork can race with try_to_unmap so vma->[purged|vm_flags] would lose consistency. > > thanks > -john > > -- > 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> -- Kind regards, Minchan Kim -- 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>