Message-ID: <20230117142140.g423hxisv7djudof@bogus>
Date:   Tue, 17 Jan 2023 14:21:40 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        richard.henderson@...aro.org, ink@...assic.park.msu.ru,
        mattst88@...il.com, vgupta@...nel.org, linux@...linux.org.uk,
        nsekhar@...com, brgl@...ev.pl, ulli.kroll@...glemail.com,
        linus.walleij@...aro.org, shawnguo@...nel.org,
        Sascha Hauer <s.hauer@...gutronix.de>, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com, tony@...mide.com,
        khilman@...nel.org, krzysztof.kozlowski@...aro.org,
        alim.akhtar@...sung.com, catalin.marinas@....com, will@...nel.org,
        guoren@...nel.org, bcain@...cinc.com, chenhuacai@...nel.org,
        kernel@...0n.name, geert@...ux-m68k.org, sammy@...my.net,
        monstr@...str.eu, tsbogend@...ha.franken.de, dinguyen@...nel.org,
        jonas@...thpole.se, stefan.kristiansson@...nalahti.fi,
        shorne@...il.com, James.Bottomley@...senpartnership.com,
        deller@....de, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu, paul.walmsley@...ive.com,
        palmer@...belt.com, aou@...s.berkeley.edu, hca@...ux.ibm.com,
        gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
        ysato@...rs.sourceforge.jp, dalias@...c.org, davem@...emloft.net,
        richard@....at, anton.ivanov@...bridgegreys.com,
        johannes@...solutions.net, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, acme@...nel.org, alexander.shishkin@...ux.intel.com,
        jolsa@...nel.org, namhyung@...nel.org, jgross@...e.com,
        srivatsa@...il.mit.edu, amakhalov@...are.com,
        pv-drivers@...are.com, boris.ostrovsky@...cle.com,
        chris@...kel.net, jcmvbkbc@...il.com, rafael@...nel.org,
        lenb@...nel.org, pavel@....cz, gregkh@...uxfoundation.org,
        mturquette@...libre.com, sboyd@...nel.org,
        daniel.lezcano@...aro.org, lpieralisi@...nel.org,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        anup@...infault.org, thierry.reding@...il.com,
        jonathanh@...dia.com, jacob.jun.pan@...ux.intel.com,
        atishp@...shpatra.org, Arnd Bergmann <arnd@...db.de>,
        yury.norov@...il.com, andriy.shevchenko@...ux.intel.com,
        linux@...musvillemoes.dk, dennis@...nel.org, tj@...nel.org,
        cl@...ux.com, rostedt@...dmis.org, mhiramat@...nel.org,
        frederic@...nel.org, paulmck@...nel.org, pmladek@...e.com,
        senozhatsky@...omium.org, john.ogness@...utronix.de,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, ryabinin.a.a@...il.com,
        glider@...gle.com, andreyknvl@...il.com, dvyukov@...gle.com,
        vincenzo.frascino@....com,
        Andrew Morton <akpm@...ux-foundation.org>, jpoimboe@...nel.org,
        linux-alpha@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-snps-arc@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-csky@...r.kernel.org,
        linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
        loongarch@...ts.linux.dev, linux-m68k@...ts.linux-m68k.org,
        linux-mips@...r.kernel.org, openrisc@...ts.librecores.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-um@...ts.infradead.org, linux-perf-users@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-xtensa@...ux-xtensa.org, linux-acpi@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-trace-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v3 00/51] cpuidle,rcu: Clean up the mess

On Tue, Jan 17, 2023 at 01:16:21PM +0000, Mark Rutland wrote:
> On Tue, Jan 17, 2023 at 11:26:29AM +0100, Peter Zijlstra wrote:
> > On Mon, Jan 16, 2023 at 04:59:04PM +0000, Mark Rutland wrote:
> > 
> > > I'm sorry to have to bear some bad news on that front. :(
> > 
> > Moo, something had to give..
> > 
> > 
> > > IIUC what's happenign here is the PSCI cpuidle driver has entered idle and RCU
> > > is no longer watching when arm64's cpu_suspend() manipulates DAIF. Our
> > > local_daif_*() helpers poke lockdep and tracing, hence the call to
> > > trace_hardirqs_off() and the RCU usage.
> > 
> > Right, strictly speaking not needed at this point, IRQs should have been
> > traced off a long time ago.
> 
> True, but there are some other calls around here that *might* end up invoking
> RCU stuff (e.g. the MTE code).
> 
> That all needs a noinstr cleanup too, which I'll sort out as a follow-up.
> 
> > > I think we need RCU to be watching all the way down to cpu_suspend(), and it's
> > > cpu_suspend() that should actually enter/exit idle context. That and we need to
> > > make cpu_suspend() and the low-level PSCI invocation noinstr.
> > > 
> > > I'm not sure whether 32-bit will have a similar issue or not.
> > 
> > I'm not seeing 32bit or Risc-V have similar issues here, but who knows,
> > maybe I missed somsething.
> 
> I reckon if they do, the core changes here give us the infrastructure to fix
> them if/when we get reports.
> 
> > In any case, the below ought to cure the ARM64 case and remove that last
> > known RCU_NONIDLE() user as a bonus.
> 
> The below works for me testing on a Juno R1 board with PSCI, using defconfig +
> CONFIG_PROVE_LOCKING=y + CONFIG_DEBUG_LOCKDEP=y + CONFIG_DEBUG_ATOMIC_SLEEP=y.
> I'm not sure how to test the LPI / FFH part, but it looks good to me.
> 
> FWIW:
> 
> Reviewed-by: Mark Rutland <mark.rutland@....com>
> Tested-by: Mark Rutland <mark.rutland@....com>
> 
> Sudeep, would you be able to give the LPI/FFH side a spin with the kconfig
> options above?
> 

Not sure if I have messed up something in my mail setup, but I did reply
earlier. I did test both DT/cpuidle-psci driver and  ACPI/LPI+FFH driver
with the fix Peter sent. I was seeing same splat as you in both DT and
ACPI boot which the patch fixed it. I used the same config as described by
you above.

-- 
Regards,
Sudeep

Powered by blists - more mailing lists