From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout02.his.huawei.com (canpmsgout02.his.huawei.com [113.46.200.217]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CC64379C22; Thu, 27 Aug 2026 01:39:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.217 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787794788; cv=none; b=X/cdWLqGNTyr5P4Lv976wdpnR9q61ZOkmwJQYHdylo2tFkFs+pxfFYotQq4SUfrV1O5UWnKCeXPgLp7Sf/xNoJxjJXBDiHbbu4bH2ppvtwMTiC34aJMo/duakcX9638AoLja1YryublDQ0JxLDsuhL4T1RMplDZlfNrsuRj8Dqo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787794788; c=relaxed/simple; bh=2MdvFAHIEshwqfWjDGepWUruAskvgBp4I4JxaicYqN4=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=f15x4nxybCrOYKyD5T9FLhh54EZmBnzldCUJGEv6aOiOooL1P1xr5XD7HhGP/OkAIqodeZ+OVXY6o5ggj0+CVYqUEWDsyaFMq0yRLve2nHqMBy9Za14s0b3/ZBJyXPNqQQcrXYuJ4yaxs96hRfIy9M55VncOmTCKO7uEqBuuXKE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=cMdkJyY7; arc=none smtp.client-ip=113.46.200.217 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="cMdkJyY7" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=6V/h+o47odsyXIkxbfxkMIxGGEws32dxuRVF3fbP4lk=; b=cMdkJyY79rhFemLfJnmHtfBmdzU4z+QZw2teLc9nRsAh3EPFUwYTH4Yu367yK9WgOoNsrBLDD iFj80RBXDylV0su8ss449sBZUOus1vFmd53cu/GJNuvppeargZOewslDIfQiP/XXa66m9ImU+5T qbqnm1caQxoju3xi/C2YEfI= Received: from mail.maildlp.com (unknown [172.19.163.104]) by canpmsgout02.his.huawei.com (SkyGuard) with ESMTPS id 4hVkSg1p2Szcb0T; Thu, 27 Aug 2026 09:29:07 +0800 (CST) Received: from kwepemf100001.china.huawei.com (unknown [7.202.181.215]) by mail.maildlp.com (Postfix) with ESMTPS id 4F6974057F; Thu, 27 Aug 2026 09:39:41 +0800 (CST) Received: from [10.67.121.90] (10.67.121.90) by kwepemf100001.china.huawei.com (7.202.181.215) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Thu, 27 Aug 2026 09:39:40 +0800 Message-ID: <7572871f-7533-4373-9ebf-5c392a57140f@huawei.com> Date: Thu, 27 Aug 2026 09:39:40 +0800 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] ACPI: processor: Add acpi_processor_start() back to parse _CPC tables before CPU online To: Pengjie Zhang , , , , CC: , , , , , , , , , , References: <20260120113242.3843463-1-zhenglifeng1@huawei.com> From: "zhenglifeng (A)" In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemf100001.china.huawei.com (7.202.181.215) Hi Pengjie, On 8/26/2026 3:59 PM, Pengjie Zhang wrote: > Hi Lifeng, > > On 1/20/2026 7:32 PM, Lifeng Zheng wrote: >> Currently, if boot with maxcpus less than NR_CPUS, the cppc_cpufreq driver >> will fail to register. Because it requires the domain information of all >> possible CPUs to construct shared_cpu_map, which shows the CPUs that share >> the same domain. >> >> Commit c1385c1f0ba3 ("ACPI: processor: Simplify initial onlining to use >> same path for cold and hotplug") removes probe() of acpi_processor_driver >> and makes acpi_cppc_processor_probe() only being called the first time CPU >> goes online. This means that CPUs that haven't yet gone online will not >> have pre-parsed _CPC objects and causes cppc_cpufreq driver register fail. >> >> Add acpi_processor_start() back as the probe() callback of >> acpi_processor_driver and call acpi_cppc_processor_probe() in it to make >> sure all _CPC tables will be parsed when acpi_processor_driver registered. >> >> Fixes: c1385c1f0ba3 ("ACPI: processor: Simplify initial onlining to use same path for cold and hotplug") >> Signed-off-by: Lifeng Zheng >> --- >>   drivers/acpi/processor_driver.c | 30 ++++++++++++++++++++++++++---- >>   1 file changed, 26 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c >> index 65e779be64ff..c8b4daf580b0 100644 >> --- a/drivers/acpi/processor_driver.c >> +++ b/drivers/acpi/processor_driver.c >> @@ -33,6 +33,7 @@ MODULE_AUTHOR("Paul Diefenbaugh"); >>   MODULE_DESCRIPTION("ACPI Processor Driver"); >>   MODULE_LICENSE("GPL"); >>   +static int acpi_processor_start(struct device *dev); >>   static int acpi_processor_stop(struct device *dev); >>     static const struct acpi_device_id processor_device_ids[] = { >> @@ -46,6 +47,7 @@ static struct device_driver acpi_processor_driver = { >>       .name = "processor", >>       .bus = &cpu_subsys, >>       .acpi_match_table = processor_device_ids, >> +    .probe = acpi_processor_start, >>       .remove = acpi_processor_stop, >>   }; >>   @@ -162,10 +164,6 @@ static int __acpi_processor_start(struct acpi_device *device) >>       if (!pr) >>           return -ENODEV; >>   -    result = acpi_cppc_processor_probe(pr); >> -    if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS)) >> -        dev_dbg(&device->dev, "CPPC data invalid or not present\n"); >> - >>       if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver) >>           acpi_processor_power_init(pr); >>   @@ -192,6 +190,30 @@ static int __acpi_processor_start(struct acpi_device *device) >>       return result; >>   } >>   +static int acpi_processor_start(struct device *dev) >> +{ >> +    struct acpi_device *device = ACPI_COMPANION(dev); >> +    struct acpi_processor *pr; >> +    int result; >> + >> +    if (!device) >> +        return -ENODEV; >> + >> +    pr = acpi_driver_data(device); >> +    if (!pr) >> +        return -ENODEV; >> + >> +    /* Protect against concurrent CPU hotplug operations */ >> +    cpu_hotplug_disable(); >> +    result = acpi_cppc_processor_probe(pr); >> +    cpu_hotplug_enable(); >> + >> +    if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS)) >> +        dev_dbg(&device->dev, "CPPC data invalid or not present\n"); >> + >> +    return 0; >> +} >> + >>   static int acpi_processor_stop(struct device *dev) >>   { >>       struct acpi_device *device = ACPI_COMPANION(dev); > I reproduced the issue described by this patch on the latest kernel at > commit 45c13f3f9e3bb15f. > > On my system, CPU0 and CPU1 belong to the same software-coordinated > frequency domain. After booting with maxcpus=1, CPU1 is present but > offline, and its CPC descriptor is not parsed. > > Consequently, acpi_get_psd_map() skips CPU1 and constructs an > incomplete shared_cpu_map containing only CPU0. > > When CPU1 is subsequently brought online: > > echo 1 > /sys/devices/system/cpu/cpu1/online > > the cpufreq core creates an overlapping policy and attempts to create > the existing cpu0/cpufreq symbolic link again, resulting in the > following warnings: > ... > sysfs_warn_dup > sysfs_do_create_link_sd > sysfs_create_link > add_cpu_dev_symlink > cpufreq_policy_online > cpufreq_online > cpuhp_cpufreq_online > ... > processor cpu0: cpufreq symlink creation failed > > freq_qos_add_request() called for active request > WARNING: kernel/power/qos.c:658 at freq_qos_add_request > > The affected CPU masks are also inconsistent: > > $ cat /sys/devices/system/cpu/cpu0/cpufreq/affected_cpus > 0 > > $ cat /sys/devices/system/cpu/cpu1/cpufreq/affected_cpus > 0 1 > > After applying this patch on top of commit 45c13f3f9e3bb15f, the CPC > descriptors are parsed before the CPUs are brought online. The > shared_cpu_map is constructed correctly, and CPU1 can be brought > online without triggering the duplicate sysfs link or active QoS > request warnings. > > This patch fixes the issue in my testing. so， > > Tested-by: Pengjie Zhang > Reviewed-by: Pengjie Zhang > Thanks for the testing!