On 04/17/2013 10:10 PM, Robin Holt wrote: > On Wed, Apr 17, 2013 at 10:55:26AM +0800, Xiao Guangrong wrote: >> On 04/17/2013 02:08 AM, Robin Holt wrote: >>> On Tue, Apr 16, 2013 at 09:07:20PM +0800, Xiao Guangrong wrote: >>>> On 04/16/2013 07:43 PM, Robin Holt wrote: >>>>> Argh. Taking a step back helped clear my head. >>>>> >>>>> For the -stable releases, I agree we should just go with your >>>>> revert-plus-hlist_del_init_rcu patch. I will give it a test >>>>> when I am in the office. >>>> >>>> Okay. Wait for your test report. Thank you in advance. >>>> >>>>> >>>>> For the v3.10 release, we should work on making this more >>>>> correct and completely documented. >>>> >>>> Better document is always welcomed. >>>> >>>> Double call ->release is not bad, like i mentioned it in the changelog: >>>> >>>> it is really rare (e.g, can not happen on kvm since mmu-notify is unregistered >>>> after exit_mmap()) and the later call of multiple ->release should be >>>> fast since all the pages have already been released by the first call. >>>> >>>> But, of course, it's great if you have a _light_ way to avoid this. >>> >>> Getting my test environment set back up took longer than I would have liked. >>> >>> Your patch passed. I got no NULL-pointer derefs. >> >> Thanks for your test again. >> >>> >>> How would you feel about adding the following to your patch? >> >> I prefer to make these changes as a separate patch, this change is the >> improvement, please do not mix it with bugfix. > > I think your "improvement" classification is a bit deceiving. My previous > patch fixed the bug in calling release multiple times. Your patch without > this will reintroduce that buggy behavior. Just because the bug is already > worked around by KVM does not mean it is not a bug. As your tested, calling ->release() multiple times can work, but just make your testcase more _slower_. So your changes is trying to speed it up - it is a improvement. Well, _if_ it is really a bug, could you please do not fix two bugs in one patch? Thanks! -- 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>