Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <fbfbb793-78ce-2b5a-307f-c6e78a926db3@huawei.com>
Date:   Wed, 22 Jun 2022 15:49:02 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.1
Subject: Re: [aarch64] INFO: rcu_sched detected expedited stalls on CPUs/tasks
To:     Bruno Goncalves <bgoncalv@redhat.com>
CC:     Pierre Gondois <pierre.gondois@arm.com>,
        <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        CKI Project <cki-project@redhat.com>,
        Ionela Voinescu <Ionela.Voinescu@arm.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>
References: <CA+QYu4qTWaDzep2GGxm-63r-xJOFf2rFCCNhWupAgZdKE7HV6w@mail.gmail.com>
 <99a207dc-93cd-1bea-2ffc-404a9f6587bf@arm.com>
 <CA+QYu4o0OqdwZYFCgCzm2CMHA7pM3nQ+j0_VbHtpFcdJmkMbhw@mail.gmail.com>
 <fe20591a-96bf-2ac5-c97f-442c2b36c455@arm.com>
 <CA+QYu4rFB0-no98R0jfzDi2z1Q-aXsEyj1+j-G7RNBi1=3SLkQ@mail.gmail.com>
 <90175f7e-0a2f-c83d-6fb5-916f885bbe81@huawei.com>
 <CA+QYu4r9Z1X3b-PxqcQx3OkdASkon9OvPAVWJcqHLtc2uPkFtA@mail.gmail.com>
From:   John Garry <john.garry@huawei.com>
In-Reply-To: <CA+QYu4r9Z1X3b-PxqcQx3OkdASkon9OvPAVWJcqHLtc2uPkFtA@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 22/06/2022 15:40, Bruno Goncalves wrote:

Hi Bruno,

> With the config change that does not set
> CONFIG_RCU_EXP_CPU_STALL_TIMEOUT the problem seems to be fixed for us.
> The newer Fedora kernels already have the config fixed.
> 

OK, thanks for the info. Well those debug options I enabled didn't cause 
problems previously. I'll see if it is one in particular and go from there.

> 
>> On v5.19-rc3 I just enabled some debug configs on a vanilla kernel and
>> can easily reproduce a RCU stall on boot, as below.
>>
>> CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=0 for me, that being the default.
>>
>>    Table To iBMC Success.
>> GetVariable Status : Not Found.
>> [    0.000000] Booting Linux on physical CPU 0x0000010000 [0x410fd082]
>> [    0.000000] Linux version 5.19.0-rc3-00001-gd8610c1c16e8
>> (john@debian) (gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU
>> Binutils for Debian) 2.37) #187 SMP PREEMPT Wed Jun 22 14:08:56 BST 2022
>> [    0.000000] Machine model: Hisilicon PhosphorV660 Development Board
>> [    0.000000] efi: EFI v2.60 by EDK II
>> [    0.000000] efi: SMBIOS=0x3eff0000 SMBIOS 3.0=0x39aa0000
>> ACPI=0x39b70000 ACPI 2.0=0x39b70014 MEMATTR=0x3b8d0018
>> MEMRESERVE=0x3a002d18

Thanks!