From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B52143EDE59; Tue, 12 May 2026 18:03:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778609007; cv=none; b=AnIpslEYuE13pLpN57sOgs9M9w/1PyzwG8sAWW+pJ+VwyvZlgDWLeNMIQVgEe7CwONkxmryJMBtLrP9raJZVAxOQRUTdU6TNUVliu4fnWdcEfeoegYhk00Ca6UapbTF6jIzONAciUpzn4ftfyvlhRYVIKIU3ftjWKDr9A+j1/5E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778609007; c=relaxed/simple; bh=qdFCimMjFF3uwCyhbINAknxvPwRKRq2AeGMJO9EVSwU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ATcJWUJcTC0s442gUX7s/gBrldE1sU68oH70x6SaJXjl8BshnMyaayDgam1HDy2LBGvEN7NIu98BoL/Gvl60iud7scGLoM57pcm2huoY0VW9KdMl5nwciWxOV0CqVRSpGhUxSNhNP7xOBrTlNlEMmNlhg6YxsQ8aHmRSnE/oZEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=s6yI1psV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="s6yI1psV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E73BC2BCB0; Tue, 12 May 2026 18:03:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778609007; bh=qdFCimMjFF3uwCyhbINAknxvPwRKRq2AeGMJO9EVSwU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s6yI1psVUFU1kuZJzAq5wZF7qACk50xsglP6e3/cVJSeEvEIHEYQXzMZpmP0au3Od +3afqjRKZOYMKOfPY4C3EZm36gDHFNGA82xjd/CoLyq+w7d9NtsoGvLngGu9TPUFBI J0gj828H9qm1hBz6/nuDJ2LhMZejuJs982bSK6Sg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Kelley , Jinjie Ruan , "Rafael J. Wysocki" Subject: [PATCH 7.0 009/307] ACPI: CPPC: Fix related_cpus inconsistency during CPU hotplug Date: Tue, 12 May 2026 19:36:44 +0200 Message-ID: <20260512173940.321218853@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173940.117428952@linuxfoundation.org> References: <20260512173940.117428952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jinjie Ruan commit 75141a770f4f8225d316f6c7e146723a32e9720e upstream. When concurrently bringing up and down two SMT threads of a physical core, many warning call traces occur as below: The issue timeline is as follows: 1. When the system starts, cpufreq: CPU: 220, policy->related_cpus: 220-221, policy->cpus: 220-221 2. Offline CPU 220 and CPU 221. 3. Online CPU 220 - CPU 221 is now offline, as acpi_get_psd_map() use for_each_online_cpu(), so the cpu_data->shared_cpu_map, policy->cpus, and related_cpus has only CPU 220. cpufreq: CPU: 220, policy->related_cpus: 220, policy->cpus: 220 4. Offline CPU 220 5. Online CPU 221, the below call trace occurs: - Since CPU 220 and CPU 221 share one policy, and policy->related_cpus = 220 after step 3, so CPU 221 is not in policy->related_cpus but per_cpu(cpufreq_cpu_data, cpu221) is not NULL. After reverting commit 56eb0c0ed345 ("ACPI: CPPC: Fix remaining for_each_possible_cpu() to use online CPUs"), the issue disappeared. The _PSD (P-State Dependency) defines the hardware-level dependency of frequency control across CPU cores. Since this relationship is a physical attribute of the hardware topology, it remains constant regardless of the online or offline status of the CPUs. Using for_each_online_cpu() in acpi_get_psd_map() is problematic. If a CPU is offline, it will be excluded from the shared_cpu_map. Consequently, if that CPU is brought online later, the kernel will fail to recognize it as part of any shared frequency domain. Switch back to for_each_possible_cpu() to ensure that all cores defined in the ACPI tables are correctly mapped into their respective performance domains from the start. This aligns with the logic of policy->related_cpus, which must encompass all potentially available cores in the domain to prevent logic gaps during CPU hotplug operations. To resolve the original issue regarding the "nosmt" or "nosmt=force" boot parameter, as send_pcc_cmd() function already does if (!desc) continue, so reverting that loop back to for_each_possible_cpu() is ok, only need to change the match_cpc_ptr NULL case in acpi_get_psd_map() to continue as Sean suggested. How to reproduce, on arm64 machine with SMT support which use acpi cppc cpufreq driver: bash test.sh 220 & bash test.sh 221 & The test.sh is as below: while true do echo 0 > /sys/devices/system/cpu/cpu${1}/online sleep 0.5 cat /sys/devices/system/cpu/cpu${1}/cpufreq/related_cpus echo 1 > /sys/devices/system/cpu/cpu${1}/online cat /sys/devices/system/cpu/cpu${1}/cpufreq/related_cpus done CPU: 221 PID: 1119 Comm: cpuhp/221 Kdump: loaded Not tainted 6.6.0debug+ #5 Hardware name: To be filled by O.E.M. S920X20/BC83AMDA01-7270Z, BIOS 20.39 09/04/2024 pstate: a1400009 (NzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : cpufreq_online+0x8ac/0xa90 lr : cpuhp_cpufreq_online+0x18/0x30 sp : ffff80008739bce0 x29: ffff80008739bce0 x28: 0000000000000000 x27: ffff28400ca32200 x26: 0000000000000000 x25: 0000000000000003 x24: ffffd483503ff000 x23: ffffd483504051a0 x22: ffffd48350024a00 x21: 00000000000000dd x20: 000000000000001d x19: ffff28400ca32000 x18: 0000000000000000 x17: 0000000000000020 x16: ffffd4834e6a3fc8 x15: 0000000000000020 x14: 0000000000000008 x13: 0000000000000001 x12: 00000000ffffffff x11: 0000000000000040 x10: ffffd48350430728 x9 : ffffd4834f087c78 x8 : 0000000000000001 x7 : ffff2840092bdf00 x6 : ffffd483504264f0 x5 : ffffd48350405000 x4 : ffff283f7f95cc60 x3 : 0000000000000000 x2 : ffff53bc2f94b000 x1 : 00000000000000dd x0 : 0000000000000000 Call trace: cpufreq_online+0x8ac/0xa90 cpuhp_cpufreq_online+0x18/0x30 cpuhp_invoke_callback+0x128/0x580 cpuhp_thread_fun+0x110/0x1b0 smpboot_thread_fn+0x140/0x190 kthread+0xec/0x100 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- Cc: All applicable Fixes: 56eb0c0ed345 ("ACPI: CPPC: Fix remaining for_each_possible_cpu() to use online CPUs") Co-developed-by: Sean Kelley Signed-off-by: Sean Kelley Signed-off-by: Jinjie Ruan [ rjw: Changelog edits ] Link: https://patch.msgid.link/20260417040112.3727756-1-ruanjinjie@huawei.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/acpi/cppc_acpi.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -362,7 +362,7 @@ static int send_pcc_cmd(int pcc_ss_id, u end: if (cmd == CMD_WRITE) { if (unlikely(ret)) { - for_each_online_cpu(i) { + for_each_possible_cpu(i) { struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i); if (!desc) @@ -524,13 +524,13 @@ int acpi_get_psd_map(unsigned int cpu, s else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY) cpu_data->shared_type = CPUFREQ_SHARED_TYPE_ANY; - for_each_online_cpu(i) { + for_each_possible_cpu(i) { if (i == cpu) continue; match_cpc_ptr = per_cpu(cpc_desc_ptr, i); if (!match_cpc_ptr) - goto err_fault; + continue; match_pdomain = &(match_cpc_ptr->domain_info); if (match_pdomain->domain != pdomain->domain)