From: Vladimir Oltean <olteanv@gmail.com> To: Kurt Kanzenbach <kurt.kanzenbach@linutronix.de> Cc: Alison Wang <alison.wang@nxp.com>, catalin.marinas@arm.com, will@kernel.org, paulmck@kernel.org, mw@semihalf.com, leoyang.li@nxp.com, vladimir.oltean@nxp.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Anna-Maria Gleixner <anna-maria@linutronix.de>, Thomas Gleixner <tglx@linutronix.de> Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Date: Mon, 3 Aug 2020 11:16:25 +0300 [thread overview] Message-ID: <20200803081625.czdfwcpw5emcd4ls@skbuf> (raw) In-Reply-To: <873654m9zi.fsf@kurt> On Mon, Aug 03, 2020 at 10:04:01AM +0200, Kurt Kanzenbach wrote: > On Thu Jul 30 2020, Vladimir Oltean wrote: > > On Thu, Jul 30, 2020 at 09:23:44AM +0200, Kurt Kanzenbach wrote: > >> On Wed Jul 29 2020, Vladimir Oltean wrote: > >> > For more context, here is my original report of the issue: > >> > https://lkml.org/lkml/2020/6/4/1062 > >> > > >> > Just like you, I could not reproduce the RCU stalls and system hang on a > >> > 5.6-rt kernel, just on mainline and derivatives, using the plain > >> > defconfig. > >> > > >> > The issue is not specific to Layerscape or i.MX8, but rather I was able > >> > to see the same behavior on Marvell Armada 37xx as well as Qualcomm > >> > MSM8976. > >> > > >> > So, while of course I agree that disabling IRQ time accounting for arm64 > >> > isn't a real solution, it isn't by far an exaggerated proposal either. > >> > Nonetheless, the patch is just a RFC and should be treated as such. We > >> > are at a loss when it comes to debugging this any further and we would > >> > appreciate some pointers. > >> > >> Yeah, sure. I'll try to reproduce this issue first. So it triggers with: > >> > >> * arm64 > >> * mainline, not -rt kernel > >> * opened serial console > >> * irq accounting enabled > >> > >> Anything else? > >> > >> Thanks, > >> Kurt > > > > Thanks for giving a helping hand, Kurt. The defconfig should be enough. > > In the interest of full disclosure, the only arm64 device on which we > > didn't reproduce this was the 16-core LX2160A. But we did reproduce on > > that with maxcpus=1 though. And also on msm8976 with all 8 cores booted. > > Just mentioning this in case you're testing on a 16-core system, you > > might want to reduce the number a bit. > > OK. I've reproduced it on a Marvell Armada SoC with v5.6 mainline. See > splats below. Running with irq time accounting enabled, kills the > machine immediately. However, I'm not getting the possible deadlock > warnings in 8250 as you did. So that might be unrelated. > Yes, the console lockdep warnings are unrelated. They are discussed here: https://lore.kernel.org/lkml/CAHQZ30BnfX+gxjPm1DUd5psOTqbyDh4EJE=2=VAMW_VDafctkA@mail.gmail.com/ > Unfortunately I have no idea what to debug here. > > Thanks, > Kurt So, this means we could submit a formal version of this patch? :) Thanks, -Vladimir
WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Oltean <olteanv@gmail.com> To: Kurt Kanzenbach <kurt.kanzenbach@linutronix.de> Cc: paulmck@kernel.org, Anna-Maria Gleixner <anna-maria@linutronix.de>, catalin.marinas@arm.com, Alison Wang <alison.wang@nxp.com>, linux-kernel@vger.kernel.org, leoyang.li@nxp.com, vladimir.oltean@nxp.com, Thomas Gleixner <tglx@linutronix.de>, mw@semihalf.com, will@kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Date: Mon, 3 Aug 2020 11:16:25 +0300 [thread overview] Message-ID: <20200803081625.czdfwcpw5emcd4ls@skbuf> (raw) In-Reply-To: <873654m9zi.fsf@kurt> On Mon, Aug 03, 2020 at 10:04:01AM +0200, Kurt Kanzenbach wrote: > On Thu Jul 30 2020, Vladimir Oltean wrote: > > On Thu, Jul 30, 2020 at 09:23:44AM +0200, Kurt Kanzenbach wrote: > >> On Wed Jul 29 2020, Vladimir Oltean wrote: > >> > For more context, here is my original report of the issue: > >> > https://lkml.org/lkml/2020/6/4/1062 > >> > > >> > Just like you, I could not reproduce the RCU stalls and system hang on a > >> > 5.6-rt kernel, just on mainline and derivatives, using the plain > >> > defconfig. > >> > > >> > The issue is not specific to Layerscape or i.MX8, but rather I was able > >> > to see the same behavior on Marvell Armada 37xx as well as Qualcomm > >> > MSM8976. > >> > > >> > So, while of course I agree that disabling IRQ time accounting for arm64 > >> > isn't a real solution, it isn't by far an exaggerated proposal either. > >> > Nonetheless, the patch is just a RFC and should be treated as such. We > >> > are at a loss when it comes to debugging this any further and we would > >> > appreciate some pointers. > >> > >> Yeah, sure. I'll try to reproduce this issue first. So it triggers with: > >> > >> * arm64 > >> * mainline, not -rt kernel > >> * opened serial console > >> * irq accounting enabled > >> > >> Anything else? > >> > >> Thanks, > >> Kurt > > > > Thanks for giving a helping hand, Kurt. The defconfig should be enough. > > In the interest of full disclosure, the only arm64 device on which we > > didn't reproduce this was the 16-core LX2160A. But we did reproduce on > > that with maxcpus=1 though. And also on msm8976 with all 8 cores booted. > > Just mentioning this in case you're testing on a 16-core system, you > > might want to reduce the number a bit. > > OK. I've reproduced it on a Marvell Armada SoC with v5.6 mainline. See > splats below. Running with irq time accounting enabled, kills the > machine immediately. However, I'm not getting the possible deadlock > warnings in 8250 as you did. So that might be unrelated. > Yes, the console lockdep warnings are unrelated. They are discussed here: https://lore.kernel.org/lkml/CAHQZ30BnfX+gxjPm1DUd5psOTqbyDh4EJE=2=VAMW_VDafctkA@mail.gmail.com/ > Unfortunately I have no idea what to debug here. > > Thanks, > Kurt So, this means we could submit a formal version of this patch? :) Thanks, -Vladimir _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-08-03 8:16 UTC|newest] Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-29 3:39 [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Alison Wang 2020-07-29 3:39 ` Alison Wang 2020-07-29 8:40 ` Kurt Kanzenbach 2020-07-29 8:40 ` Kurt Kanzenbach 2020-07-29 8:50 ` [EXT] " Alison Wang 2020-07-29 8:50 ` Alison Wang 2020-07-29 9:49 ` Vladimir Oltean 2020-07-29 9:49 ` Vladimir Oltean 2020-07-30 7:23 ` Kurt Kanzenbach 2020-07-30 7:23 ` Kurt Kanzenbach 2020-07-30 8:22 ` Vladimir Oltean 2020-07-30 8:22 ` Vladimir Oltean 2020-08-03 8:04 ` Kurt Kanzenbach 2020-08-03 8:04 ` Kurt Kanzenbach 2020-08-03 8:16 ` Vladimir Oltean [this message] 2020-08-03 8:16 ` Vladimir Oltean 2020-08-03 9:51 ` Robin Murphy 2020-08-03 9:51 ` Robin Murphy 2020-08-03 11:38 ` Vladimir Oltean 2020-08-03 11:38 ` Vladimir Oltean 2020-08-03 11:48 ` Valentin Schneider 2020-08-03 11:48 ` Valentin Schneider 2020-08-03 13:24 ` Marc Zyngier 2020-08-03 13:24 ` Marc Zyngier 2020-08-03 10:02 ` Thomas Gleixner 2020-08-03 10:02 ` Thomas Gleixner 2020-08-03 10:49 ` Thomas Gleixner 2020-08-03 10:49 ` Thomas Gleixner 2020-08-03 11:41 ` Vladimir Oltean 2020-08-03 11:41 ` Vladimir Oltean 2020-08-03 15:13 ` Thomas Gleixner 2020-08-03 15:13 ` Thomas Gleixner 2020-08-03 15:47 ` Valentin Schneider 2020-08-03 15:47 ` Valentin Schneider 2020-08-03 16:14 ` Vladimir Oltean 2020-08-03 16:14 ` Vladimir Oltean 2020-08-03 19:22 ` Thomas Gleixner 2020-08-03 19:22 ` Thomas Gleixner 2020-08-03 23:59 ` Valentin Schneider 2020-08-03 23:59 ` Valentin Schneider 2020-08-05 8:50 ` Dietmar Eggemann 2020-08-05 8:50 ` Dietmar Eggemann 2020-08-05 13:40 ` peterz 2020-08-05 13:40 ` peterz 2020-08-05 13:56 ` Valentin Schneider 2020-08-05 13:56 ` Valentin Schneider 2020-08-05 15:31 ` peterz 2020-08-05 15:31 ` peterz 2020-08-06 9:41 ` Thomas Gleixner 2020-08-06 9:41 ` Thomas Gleixner 2020-08-06 11:45 ` peterz 2020-08-06 11:45 ` peterz 2020-08-06 13:27 ` Paul E. McKenney 2020-08-06 13:27 ` Paul E. McKenney 2020-08-06 19:03 ` Thomas Gleixner 2020-08-06 19:03 ` Thomas Gleixner 2020-08-06 20:39 ` Paul E. McKenney 2020-08-06 20:39 ` Paul E. McKenney 2020-08-06 18:58 ` Thomas Gleixner 2020-08-06 18:58 ` Thomas Gleixner 2020-08-06 9:34 ` Thomas Gleixner 2020-08-06 9:34 ` Thomas Gleixner
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20200803081625.czdfwcpw5emcd4ls@skbuf \ --to=olteanv@gmail.com \ --cc=alison.wang@nxp.com \ --cc=anna-maria@linutronix.de \ --cc=catalin.marinas@arm.com \ --cc=kurt.kanzenbach@linutronix.de \ --cc=leoyang.li@nxp.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=mw@semihalf.com \ --cc=paulmck@kernel.org \ --cc=tglx@linutronix.de \ --cc=vladimir.oltean@nxp.com \ --cc=will@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.