Re: [clear_page] 0ad07c8104 BUG: unable to handle kernel NULL pointer dereference at 0000000000000040

[Fengguang Wu]

Hi Borislav,

On Sat, Feb 18, 2017 at 03:48:00PM +0100, Borislav Petkov wrote:
> Guys,
>
> please fix the 0day bot reporting. See below for more info.
>
> On Sat, Feb 18, 2017 at 01:01:53PM +0800, Fengguang Wu wrote:
> > Greetings,
> >
> > 0day kernel testing robot got the below dmesg and the first bad commit is
> >
> > https://github.com/0day-ci/linux Borislav-Petkov/x86-Optimize-clear_page/20170210-053052
>
> Can you make this point to the actual commit on github?
>
> Your tree there has currently 47K branches and navigating through the
> web interface takes forever.

Good point! I noticed it too while sending out the report. It'll be
showed as this in future:

       https://github.com/0day-ci/linux/commits/Borislav-Petkov/x86-Optimize-clear_page/20170210-053052

> > commit 0ad07c8104eb5c12dfcb86581c1cc657183496cc
> > Author:     Borislav Petkov <bp@xxxxxxx>
> > AuthorDate: Thu Feb 9 20:51:25 2017 +0100
> > Commit:     0day robot <fengguang.wu@xxxxxxxxx>
> > CommitDate: Fri Feb 10 05:30:58 2017 +0800
> >
> >      x86: Optimize clear_page()
> >
> >      Currently, we CALL clear_page() which then JMPs to the proper function
> >      chosen by the alternatives.
> >
> >      What we should do instead is CALL the proper function directly. (This
> >      was something Ingo suggested a while ago). So let's do that.
> >
> >      Measuring our favourite kernel build workload shows that there are no
> >      significant changes in performance.
> >
> >      ...
> >
> >      Signed-off-by: Borislav Petkov <bp@xxxxxxx>
>
> Then, this is an old patch. You already sent me a bug report, I replied
> with a fix but you didn't test the fix. Instead you're sending the same
> old report.

Sorry the 2nd report was send out manually and I only checked the
emails in my _current_ mbox. Since the previous report email has been
archived, it slipped through the duplication check.

> Here's the fix: https://lists.01.org/pipermail/lkp/2017-February/005573.html
>
> And the upstream submission of the new version:
>
> https://lkml.kernel.org/r/20170215111927.emdgxf2pide3kwro@xxxxxxx
>
> Please fix the bot to pay attention to replies. If there is a special
> way I should reply with a fix so that the bot retests with the same
> config, please let me know.

CC Xiaolong. It's possible to automate the test-of-fixup-patches.
Firstly find out the original email report by the Message-ID being
replied to. Then fetch all the information required for deciding where
the patch should be applied to, parameters to auto-testing the patch.

> In general, I think it would be a very cool idea to be able to reply to
> the bot and say, "Dear bot, can you test this fix ontop with the exact
> same guest, vm, kernel .config etc.
>
> That would be lovely.

Yeah we have a TODO to do email based on-demand service, which looks
close to your proposal.

> Thanks and keep up the good work!

Thanks,
Fengguang