| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1>
Date: Fri, 29 Jul 2022 08:28:13 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Michel Lespinasse <michel@...pinasse.org>
Cc: Peter Zijlstra <peterz@...radead.org>, rth@...ddle.net,
ink@...assic.park.msu.ru, mattst88@...il.com, vgupta@...nel.org,
linux@...linux.org.uk, 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, 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, benh@...nel.crashing.org,
paulus@...ba.org, 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, mark.rutland@....com,
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,
sudeep.holla@....com, agross@...nel.org,
bjorn.andersson@...aro.org, anup@...infault.org,
thierry.reding@...il.com, jonathanh@...dia.com,
jacob.jun.pan@...ux.intel.com, Arnd Bergmann <arnd@...db.de>,
yury.norov@...il.com, andriy.shevchenko@...ux.intel.com,
linux@...musvillemoes.dk, rostedt@...dmis.org, pmladek@...e.com,
senozhatsky@...omium.org, john.ogness@...utronix.de,
frederic@...nel.org, quic_neeraju@...cinc.com,
josh@...htriplett.org, mathieu.desnoyers@...icios.com,
jiangshanlai@...il.com, joel@...lfernandes.org,
juri.lelli@...hat.com, vincent.guittot@...aro.org,
dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
bristot@...hat.com, vschneid@...hat.com, jpoimboe@...nel.org,
linux-alpha@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-snps-arc@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
linux-csky@...r.kernel.org, linux-hexagon@...r.kernel.org,
linux-ia64@...r.kernel.org, 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,
xen-devel@...ts.xenproject.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,
rcu@...r.kernel.org, rh0@...com
Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE
Or better yet, try the patch that Rafael proposed. ;-)
Thanx, Paul
On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote:
> On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote:
> > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote:
> > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote:
> > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote:
> > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on
> > > > > Xeons") wrecked intel_idle in two ways:
> > > > >
> > > > > - must not have tracing in idle functions
> > > > > - must return with IRQs disabled
> > > > >
> > > > > Additionally, it added a branch for no good reason.
> > > > >
> > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons")
> > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > > >
> > > > After this change was introduced, I am seeing "WARNING: suspicious RCU
> > > > usage" when booting a kernel with debug options compiled in. Please
> > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea
> > > > and is still present in v5.19-rc8.
> > > >
> > > > I'm not sure, is this too late to fix or revert in v5.19 final ?
> > >
> > > I finally got a chance to take a quick look at this.
> > >
> > > The rcu_eqs_exit() function is making a lockdep complaint about
> > > being invoked with interrupts enabled. This function is called from
> > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state()
> > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables
> > > interrupts before invoking rcu_eqs_exit().
> > >
> > > The only other call to rcu_idle_exit() does not disable interrupts,
> > > but it is via rcu_user_exit(), which would be a very odd choice for
> > > cpuidle_enter_state().
> > >
> > > It seems unlikely, but it might be that it is the use of local_irq_save()
> > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing
> > > the trouble. If this is the case, then the commit shown below would
> > > help. Note that this commit removes the warning from lockdep, so it
> > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable
> > > equivalent debugging.
> > >
> > > Could you please try your test with the -rce commit shown below applied?
> >
> > Thanks for looking into it.
>
> And thank you for trying this shot in the dark!
>
> > After checking out Peter's commit 32d4fd5751ea,
> > cherry picking your commit ed4ae5eff4b3,
> > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config,
> > I am now seeing this a few seconds into the boot:
> >
> > [ 3.010650] ------------[ cut here ]------------
> > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60
>
> And this is again a complaint about interrupts not being disabled.
>
> But it does appear that the problem was the lockdep complaint, and
> eliminating that did take care of part of the problem. But lockdep
> remained enabled, and you therefore hit the next complaint.
>
> > [ 3.010657] Modules linked in:
> > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1
> > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022
> > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60
>
> The most straightforward way to get to sched_clock_tick() from
> cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event().
>
> Except that it disables interrupts before invoking sched_clock_tick().
>
> > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00
> > 89 c0 48 03 1c c5 c0 98
> > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002
> > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001
> > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13
> > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80
> > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80
> > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000
> > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000
> > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0
> > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [ 3.010683] Call Trace:
> > [ 3.010685] <TASK>
> > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0
> > [ 3.010694] cpuidle_enter+0x29/0x40
> > [ 3.010697] do_idle+0x1d4/0x210
> > [ 3.010702] cpu_startup_entry+0x19/0x20
> > [ 3.010704] rest_init+0x117/0x1a0
> > [ 3.010708] arch_call_rest_init+0xa/0x10
> > [ 3.010711] start_kernel+0x6d8/0x6ff
> > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb
> > [ 3.010728] </TASK>
> > [ 3.010729] irq event stamp: 44179
> > [ 3.010730] hardirqs last enabled at (44179): [<ffffffffb2000ccb>] asm_sysvec_apic_timer_interrupt+0x1b/0x20
> > [ 3.010734] hardirqs last disabled at (44177): [<ffffffffb22003f0>] __do_softirq+0x3f0/0x498
> > [ 3.010736] softirqs last enabled at (44178): [<ffffffffb2200332>] __do_softirq+0x332/0x498
> > [ 3.010738] softirqs last disabled at (44171): [<ffffffffb16c760b>] irq_exit_rcu+0xab/0xf0
> > [ 3.010741] ---[ end trace 0000000000000000 ]---
>
> Would you be willing to try another shot in the dark, but untested
> this time? I freely admit that this is getting strange.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
> index e374c0c923dae..279f557bf60bb 100644
> --- a/kernel/sched/clock.c
> +++ b/kernel/sched/clock.c
> @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void)
> if (!static_branch_likely(&sched_clock_running))
> return;
>
> - lockdep_assert_irqs_disabled();
> + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
>
> scd = this_scd();
> __scd_stamp(scd);
Powered by blists - more mailing lists