From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753172AbcANULr (ORCPT ); Thu, 14 Jan 2016 15:11:47 -0500 Received: from arroyo.ext.ti.com ([192.94.94.40]:54301 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750964AbcANULp (ORCPT ); Thu, 14 Jan 2016 15:11:45 -0500 Subject: Re: [4.4-rc6-rt1 PATCH 0/2] ARM: am437x: boot test report To: Sebastian Andrzej Siewior References: <1451325611-21678-1-git-send-email-grygorii.strashko@ti.com> <20160112171556.GB31009@linutronix.de> <569637ED.1030304@ti.com> <5696B025.8020909@ti.com> CC: , , Sekhar Nori , linux-arm From: Grygorii Strashko Message-ID: <569800DD.7090102@ti.com> Date: Thu, 14 Jan 2016 22:11:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <5696B025.8020909@ti.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sebastian, On 01/13/2016 10:14 PM, Grygorii Strashko wrote: > On 01/13/2016 01:41 PM, Grygorii Strashko wrote: >> On 01/12/2016 07:15 PM, Sebastian Andrzej Siewior wrote: >>> * Grygorii Strashko | 2015-12-28 20:00:09 [+0200]: >>> >>> >>>> 3) Seems there are some problem with HIGHMEM :(. System crashes if I'm trying >>>> to run hackbench (see log 1). I can run hackbench only if HIGHMEM is disabled. >>>> I've also tried to disable CONFIG_CPU_SW_DOMAIN_PAN, CONFIG_ARM_PATCH_PHYS_VIRT, >>>> and CONFIG_CPUSETS, before disabling HIGHMEM. >>>> Sorry, I'll not able to investigate it further because of Christmas holidays here. >>> >>> I see. It seems not to trigger anything on x86. >> >> Yah. I saw other reports - it seems this issue is not triggered on ARM SMP also >> (as per report from Tim Sander). Will try to dig deeper. >> > > I did more tests, but still don't know what is wrong. > 1) vanilla 4.4 - no issue > 2) 4.4-rt: CONFIG_PREEMPT_RT_BASE=n and CONFIG_PREEMPT_RT_FULL=n -- no issue > 3) 4.4-rt: CONFIG_DEBUG_HIGHMEM=y -- issue is present log1 > 4) 4.4-rt: this is interesting ;) > I can run hackbench few times without issues If I run hackbench with RT priority (log2) > But I got crash immediately once I run it using non-RT priorities. Seems I've found root cause of the issue - FIX_KMAP_BEGIN offset need to be taken into account in switch_kmaps() and below diff fixes this issue for me. What I'm not fully understand is why I'm the only one who hit this issue :( New functionality was added by commit: commit a5f4c561b3b19a9bc43a81da6382b0098ebbc1fb ARM: 8415/1: early fixmap support for earlycon and it is enabled by default. Luckiness :( diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index deabc36..b9b4f9c 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -167,7 +167,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) * Clear @prev's kmap_atomic mappings */ for (i = 0; i < prev_p->kmap_idx; i++) { - int idx = i + KM_TYPE_NR * smp_processor_id(); + int idx = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id(); set_fixmap_pte(idx, __pte(0)); } @@ -175,7 +175,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p) * Restore @next_p's kmap_atomic mappings */ for (i = 0; i < next_p->kmap_idx; i++) { - int idx = i + KM_TYPE_NR * smp_processor_id(); + int idx = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id(); if (!pte_none(next_p->kmap_pte[i])) set_fixmap_pte(idx, next_p->kmap_pte[i]); -- regards, -grygorii