Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753835AbbGPGzo (ORCPT ); Thu, 16 Jul 2015 02:55:44 -0400 Received: from mail-qk0-f172.google.com ([209.85.220.172]:33982 "EHLO mail-qk0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752520AbbGPGzm (ORCPT ); Thu, 16 Jul 2015 02:55:42 -0400 MIME-Version: 1.0 In-Reply-To: References: <1437008972-9140-1-git-send-email-kamal@canonical.com> <1437008972-9140-174-git-send-email-kamal@canonical.com> Date: Thu, 16 Jul 2015 15:55:41 +0900 X-Google-Sender-Auth: Hn0E8tYL2aKgw8QocwCzkKr7y4U Message-ID: Subject: Re: [PATCH 3.19.y-ckt 173/251] clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier From: Krzysztof Kozlowski To: Duan Andy Cc: Kamal Mostafa , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "kernel-team@lists.ubuntu.com" , "daniel.lezcano@linaro.org" , Damian Eppel , "kyungmin.park@samsung.com" , "kgene@kernel.org" , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , "m.szyprowski@samsung.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6308 Lines: 147 2015-07-16 15:37 GMT+09:00 Duan Andy : > From: Kamal Mostafa Sent: Thursday, July 16, 2015 9:08 AM >> To: linux-kernel@vger.kernel.org; stable@vger.kernel.org; kernel- >> team@lists.ubuntu.com >> Cc: Kamal Mostafa; daniel.lezcano@linaro.org; kyungmin.park@samsung.com; >> Damian Eppel; kgene@kernel.org; Thomas Gleixner; linux-arm- >> kernel@lists.infradead.org; m.szyprowski@samsung.com >> Subject: [PATCH 3.19.y-ckt 173/251] clocksource: exynos_mct: Avoid >> blocking calls in the cpu hotplug notifier >> >> 3.19.8-ckt4 -stable review patch. If anyone has any objections, please >> let me know. >> >> ------------------ >> >> From: Damian Eppel >> >> commit 56a94f13919c0db5958611b388e1581b4852f3c9 upstream. >> >> Whilst testing cpu hotplug events on kernel configured with DEBUG_PREEMPT >> and DEBUG_ATOMIC_SLEEP we get following BUG message, caused by calling >> request_irq() and free_irq() in the context of hotplug notification >> (which is in this case atomic context). >> >> [ 40.785859] CPU1: Software reset >> [ 40.786660] BUG: sleeping function called from invalid context at >> mm/slub.c:1241 >> [ 40.786668] in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: >> swapper/1 >> [ 40.786678] Preemption disabled at:[< (null)>] (null) >> [ 40.786681] >> [ 40.786692] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.19.0-rc4- >> 00024-g7dca860 #36 >> [ 40.786698] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) >> [ 40.786728] [] (unwind_backtrace) from [] >> (show_stack+0x10/0x14) >> [ 40.786747] [] (show_stack) from [] >> (dump_stack+0x70/0xbc) >> [ 40.786767] [] (dump_stack) from [] >> (kmem_cache_alloc+0xd8/0x170) >> [ 40.786785] [] (kmem_cache_alloc) from [] >> (request_threaded_irq+0x64/0x128) >> [ 40.786804] [] (request_threaded_irq) from [] >> (exynos4_local_timer_setup+0xc0/0x13c) >> [ 40.786820] [] (exynos4_local_timer_setup) from [] >> (exynos4_mct_cpu_notify+0x30/0xa8) >> [ 40.786838] [] (exynos4_mct_cpu_notify) from [] >> (notifier_call_chain+0x44/0x84) >> [ 40.786857] [] (notifier_call_chain) from [] >> (__cpu_notify+0x28/0x44) >> [ 40.786873] [] (__cpu_notify) from [] >> (secondary_start_kernel+0xec/0x150) >> [ 40.786886] [] (secondary_start_kernel) from [<40008764>] >> (0x40008764) >> >> Interrupts cannot be requested/freed in the CPU_STARTING/CPU_DYING >> notifications which run on the hotplugged cpu with interrupts and >> preemption disabled. >> >> To avoid the issue, request the interrupts for all possible cpus in the >> boot code. The interrupts are marked NO_AUTOENABLE to avoid a racy >> request_irq/disable_irq() sequence. The flag prevents the >> request_irq() code from enabling the interrupt immediately. >> >> The interrupt is then enabled in the CPU_STARTING notifier of the >> hotplugged cpu and again disabled with disable_irq_nosync() in the >> CPU_DYING notifier. >> >> [ tglx: Massaged changelog to match the patch ] >> >> Fixes: 7114cd749a12 ("clocksource: exynos_mct: use (request/free)_irq >> calls for local timer registration") >> Reported-by: Krzysztof Kozlowski >> Reviewed-by: Krzysztof Kozlowski >> Tested-by: Krzysztof Kozlowski >> Tested-by: Marcin Jabrzyk >> Signed-off-by: Damian Eppel >> Cc: m.szyprowski@samsung.com >> Cc: kyungmin.park@samsung.com >> Cc: daniel.lezcano@linaro.org >> Cc: kgene@kernel.org >> Cc: linux-arm-kernel@lists.infradead.org >> Link: http://lkml.kernel.org/r/1435324984-7328-1-git-send-email- >> d.eppel@samsung.com >> Signed-off-by: Thomas Gleixner >> Signed-off-by: Kamal Mostafa >> --- >> drivers/clocksource/exynos_mct.c | 43 ++++++++++++++++++++++++++++------ >> ------ >> 1 file changed, 30 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/clocksource/exynos_mct.c >> b/drivers/clocksource/exynos_mct.c >> index 83564c9..c844616 100644 >> --- a/drivers/clocksource/exynos_mct.c >> +++ b/drivers/clocksource/exynos_mct.c >> @@ -466,15 +466,12 @@ static int exynos4_local_timer_setup(struct >> clock_event_device *evt) >> exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET); >> >> if (mct_int_type == MCT_INT_SPI) { >> - evt->irq = mct_irqs[MCT_L0_IRQ + cpu]; >> - if (request_irq(evt->irq, exynos4_mct_tick_isr, >> - IRQF_TIMER | IRQF_NOBALANCING, >> - evt->name, mevt)) { >> - pr_err("exynos-mct: cannot register IRQ %d\n", >> - evt->irq); >> + >> + if (evt->irq == -1) >> return -EIO; >> - } >> - irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], >> cpumask_of(cpu)); >> + >> + irq_force_affinity(evt->irq, cpumask_of(cpu)); >> + enable_irq(evt->irq); >> } else { >> enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0); > > In here, why not use enable_percpu_irq(evt->irq) ? > >> } >> @@ -487,10 +484,12 @@ static int exynos4_local_timer_setup(struct >> clock_event_device *evt) static void exynos4_local_timer_stop(struct >> clock_event_device *evt) { >> evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt); >> - if (mct_int_type == MCT_INT_SPI) >> - free_irq(evt->irq, this_cpu_ptr(&percpu_mct_tick)); >> - else >> + if (mct_int_type == MCT_INT_SPI) { >> + if (evt->irq != -1) >> + disable_irq_nosync(evt->irq); >> + } else { >> disable_percpu_irq(mct_irqs[MCT_L0_IRQ]); > > In here, why not use disable_percpu_irq(evt->irq) ? You know this is just a semi-automatic stable backport and this was already merged to mainline? Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/