linux-kernel - Re: Current mainline git (24e700e291d52bd2) hangs when building e.g. perf

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Date:   Sat, 9 Sep 2017 10:13:38 +0200
From:   Markus Trippelsdorf <markus@...ppelsdorf.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: Current mainline git (24e700e291d52bd2) hangs when building e.g.
 perf

On 2017.09.08 at 14:47 -0700, Andy Lutomirski wrote:
> On Fri, Sep 8, 2017 at 10:16 AM, Markus Trippelsdorf
> <markus@...ppelsdorf.de> wrote:
> > On 2017.09.08 at 09:12 -0700, Andy Lutomirski wrote:
> >> On Fri, Sep 8, 2017 at 4:30 AM, Markus Trippelsdorf
> >> <markus@...ppelsdorf.de> wrote:
> >> > On 2017.09.08 at 12:39 +0200, Markus Trippelsdorf wrote:
> >> >> On 2017.09.08 at 12:35 +0200, Ingo Molnar wrote:
> >> >> >
> >> >> > * Markus Trippelsdorf <markus@...ppelsdorf.de> wrote:
> >> >> >
> >> >> > > On 2017.09.08 at 11:16 +0200, Borislav Petkov wrote:
> >> >> > > > On Fri, Sep 08, 2017 at 10:05:36AM +0200, Borislav Petkov wrote:
> >> >> > > > > On Fri, Sep 08, 2017 at 08:26:44AM +0200, Thomas Gleixner wrote:
> >> >> > > > > > On Fri, 8 Sep 2017, Markus Trippelsdorf wrote:
> >> >> > > > > >
> >> >> > > > > > CC+ Borislav. He might have access to such a beast
> >> >> > > > >
> >> >> > > > > Can I have /proc/cpuinfo and dmesg pls, in order to see whether I have
> >> >> > > > > something similar?
> >> >> > > > >
> >> >> > > > > Private mail's fine too.
> >> >> > > >
> >> >> > > > So I don't have exactly your model - mine is model 2, stepping 3 but I see
> >> >> > > > something strange too, in dmesg:
> >> >> > >
> >> >> > > I'm pretty sure the bug is in the merged 'x86-mm-for-linus' branch:
> >> >> > > Either Andy's "PCID optimized TLB flushing" (would be my guess) or
> >> >> > > 'encrypted memory' support by Tom Lendacky.
> >> >> > >
> >> >> > > (Bisecting is hard, because sometimes I can compile stuff for over 15
> >> >> > > minutes without hitting the bug. At other times the machine locks up
> >> >> > > hard when starting X11 already.)
> >> >> >
> >> >> > Do you have the 72c0098d92ce fix?
> >> >>
> >> >> Yes. The bug still happens on the current git tree (which has the fix
> >> >> already):
> >> >
> >> > The bug is definitely caused by Andy Lutomirski's PCID optimized TLB
> >> > flushing" patches. Tom is off the hook.
> >>
> >> I'm pretty sure it can't be PCID per se, since these CPUs are way too
> >> old and are very unlikely to have PCID.
> >
> > Yes, the CPU doesn't support PCID (,but it does support PGE).
> >
> >> It could plausibly be the lazy TLB flushing changes.
> >
> > Yes, I've narrowed it down to:
> >
> > commit 94b1b03b519b81c494900cb112aa00ed205cc2d9
> > Author: Andy Lutomirski <luto@...nel.org>
> > Date:   Thu Jun 29 08:53:17 2017 -0700
> >
> >     x86/mm: Rework lazy TLB mode and TLB freshness tracking
> >
> >
> > Theoretically you guys should be able to reproduce the issue by using
> > the "nopcid" boot option.
> >
> 
> Any chance you could test with CONFIG_DEBUG_VM=y?  There are lots of
> potentially useful assertions in that code.

CONFIG_DEBUG_VM=y doesn't change anything. I still get the hard hang
without anything in the logs.

> Can you also post your /proc/cpuinfo?  And can you re-confirm that a
> problematic guest kernel is causing problems in the *host*?

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 16
model           : 4
model name      : AMD Phenom(tm) II X4 955 Processor
stepping        : 2
microcode       : 0x10000db
cpu MHz         : 3210.960
cache size      : 512 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate vmmcall npt lbrv svm_lock nrip_save
bugs            : tlb_mmatch apic_c1e fxsave_leak sysret_ss_attrs null_seg amd_e400
bogomips        : 6424.50
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

Unfortunately I cannot reproduce the qemu (kvm) problem anymore. (Perhaps
I have not tried long enough). 
Anyway, kvm has code that should handle erratum_383.

-- 
Markus