Date:   Mon, 13 Feb 2023 12:46:17 +0100 (CET)
From:   Christian Kujau <lists@nerdbynature.de>
To:     Juergen Gross <jgross@suse.com>
cc:     Linux regressions mailing list <regressions@lists.linux.dev>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        mikelley@microsoft.com, torvalds@linux-foundation.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2 5/8] x86/mtrr: revert commit 90b926e68f50
In-Reply-To: <129d8c1d-ffa6-dac2-f516-dab4fc8c6218@suse.com>
Message-ID: <6e4198c2-d79c-8ebd-82f7-3826dd807f1b@nerdbynature.de>
References: <20230209072220.6836-1-jgross@suse.com> <20230209072220.6836-6-jgross@suse.com> <9046a3cb-928a-5476-1e72-63bd197c039e@leemhuis.info> <129d8c1d-ffa6-dac2-f516-dab4fc8c6218@suse.com>
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On Mon, 13 Feb 2023, Juergen Gross wrote:
> On 10.02.23 19:59, Linux regression tracking (Thorsten Leemhuis) wrote:
> > Hi, this is your Linux kernel regression tracker.
> > 
> > On 09.02.23 08:22, Juergen Gross wrote:
> > > Commit 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled
> > > case") has introduced a regression with Xen.
> > > 
> > > Revert the patch.
> > 
> > That regression you refer to is afaics one I'm tracking[1] that was
> > introduced this cycle. That makes me wonder: could this patch be applied
> > directly to fix the issue quickly? Or are patches 1 to 4 needed as well
> > (or the whole series?) to avoid other problems?
> 
> Patches 1-4 are needed, too, as otherwise the issue claimed to be fixed
> with patch 5 would show up again.

The (last?) -rc8 version was released yesterday. Would it be possible to 
include at least (only) the revert in mainline so that 6.2 will be 
released with a working storage configuration under Xen?

Otherwise one would have to carry around that single revert manually until 
this patch series has landed in mainline, or convince all the 
distributions to do so :-\

Anyway, thanks for fixing this problem, I did not expect this to be such a 
complicated issue when I reported that thing :-)

Christian.
-- 
BOFH excuse #52:

Smell from unhygienic janitorial staff wrecked the tape heads