Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"

From: Paul Gortmaker <paul.gortmaker@windriver.com>
To: Toshi Kani <toshi.kani@hpe.com>
Cc: Borislav Petkov <bp@suse.de>,
	Richard Purdie <richard.purdie@linuxfoundation.org>,
	Toshi Kani <toshi.kani@hp.com>,
	Bruce Ashfield <bruce.ashfield@windriver.com>,
	"Hart, Darren" <darren.hart@intel.com>,
	"saul.wold" <saul.wold@intel.com>, <linux-kernel@vger.kernel.org>
Subject: Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"
Date: Mon, 7 Mar 2016 22:16:54 -0500	[thread overview]
Message-ID: <20160308031653.GE26051@windriver.com> (raw)
In-Reply-To: <1457398578.15454.421.camel@hpe.com>

[Re: runtime regression with "x86/mm/pat: Emulate PAT when it is disabled"] On 07/03/2016 (Mon 17:56) Toshi Kani wrote:

[..]

> > > It may have seemed working before, but you did not have WC configured
> > > to PAT without calling pat_init().  There was not a proper check in
> > > place to detect this error before.  Can you please check your code to
> > > see what caused this skip of pat_init()?  If you have a git tree, I can
> > > take a look as well. 
> > 
> > You already have git copies of what I'm running, since it is vanilla
> > mainline commits.  No code changes at this end whatsoever.  I did the
> > bisect on vanilla mainline.  All I took from yocto was their ".config"
> > 
> > To recap, v4.1-rc5-21-g9dac62909451 works,  v4.1-rc5-22-g9cd25aac1f44
> > fails, and v4.5-rc6 also fails.  If pat_init() isn't called then this
> > is a bug in current mainline.  I'll have a look later myself and see
> > if I can trace out how we expect to get to pat_init() and how that
> > might be skipped inadvertently unless someone beats me to it.
> 
> Oh, I see.  Can you send me the ".config" file?

I packaged the .config file for every bisect point in the original
reproducer tarball.  Let me know if you can't find them.  It should
look like this:

paul@dell760-paul:~/qemu-fail$ ls -al 00-configs/
total 92
drwxrwxr-x 23 paul paul 4096 Mar  3 10:59 .
drwxrwxr-x  5 paul paul 4096 Mar  3 11:01 ..
-rw-rw-r--  1 paul paul    0 Mar  3 10:59 00-all-dot-configs-are-in-here
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-1281-g43224b96af31
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-1625-g44d21c3f3a2e
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-3251-g4e241557fc1c
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-6547-g4570a37169d4
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-912-ge75c73ad6447
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc4-85-gd4688bdc6335
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc5-21-g9dac62909451
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc5-22-g9cd25aac1f44
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc5-23-g7202fdb1b329
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc5-27-gd838270e2516
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc5-35-g7ea402d01cb6
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc6-256-g9dda1658a9bd
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.1-rc6-296-g7ef3d7d58d9d
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.2
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.2-rc1
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.3
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.4
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.4.1
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.4.1-348-g0194c7658611
drwxrwxr-x  2 paul paul 4096 Mar  3 10:59 v4.5-rc6
paul@dell760-paul:~/qemu-fail$ 

Please check if they are present in the reproducer you downloaded.
Maybe somehow I uploaded a version without the config files.

Thanks,
Paul.
--

> 
> Thanks,
> -Toshi