From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BEC0A3161AD; Thu, 16 Jul 2026 14:09:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784210963; cv=none; b=hBltcJcq/tWJUS64A01Pz6RS6ddPQ4H4Tkevk+xCe/aw2GrKtoq9wKCCneZwE7LpVdvzGoq5yfb3PqALieQl419NjCUuLOYlvvIrSMH27qOLC4+Xrik7DJSX9ycU75CXvVuc4KEgPSQ6hJBJLl9aN04QH6D8COjeV3doq1fLFYc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784210963; c=relaxed/simple; bh=AjSP8gLezF5NGMjB/a300am3YKpdluNeBrGNKmZWUjM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kM5id9V6mDuhUudrHpkq3RG4ga/PZlnam6e2Ft4jAcuhp0xYRL4uwZHUFIAFEFS2cqgW9a5AhHWh/6RU8ggIVL1kBeY+2HoipNaBWAfeT4OV4Rkstk6rCU1DxWbhD+jWv7Qsd9OQvsvED++y5P6cNzBOdCYFtcVNCYj3plHc/jo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DWOsFopC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DWOsFopC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E90271F000E9; Thu, 16 Jul 2026 14:09:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784210962; bh=W/Kz15uU+6bNy/3Xp9Zkr8dMyCr8+gGhCxE500jQRKk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DWOsFopC1VQUqZzRXU8iXGnDskHBjR07ONFDNMOmjdpscm0LptrVqdByz4iI2q9Iv xgBdjwRUklRdlHwCE8BN+pa+DcVfvY/jUubdcLc03fyJ+b+LXXvTze5q8jhIBV+U58 YwDC076lRphwoqJ5ReAi2jTrlvJRvHOPNJoUlCwk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tianxiang Chen , Zhongqiu Han , "Rafael J. Wysocki" Subject: [PATCH 6.18 248/480] cpufreq: Fix hotplug-suspend race during reboot Date: Thu, 16 Jul 2026 15:29:55 +0200 Message-ID: <20260716133050.183211012@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133044.672218725@linuxfoundation.org> References: <20260716133044.672218725@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tianxiang Chen commit a9029dd55696c651ee46912afa2a166fa456bb3e upstream. During system reboot, cpufreq_suspend() is called via the kernel_restart() -> device_shutdown() path. Unlike the normal system suspend path, the reboot path does not call freeze_processes(), so userspace processes and kernel threads remain active. This allows CPU hotplug operations to run concurrently with cpufreq_suspend(). The original code has no synchronization with CPU hotplug, leading to a race condition where governor_data can be freed by the hotplug path while cpufreq_suspend() is still accessing it, resulting in a null pointer dereference: Unable to handle kernel NULL pointer dereference Call Trace: do_kernel_fault+0x28/0x3c cpufreq_suspend+0xdc/0x160 device_shutdown+0x18/0x200 kernel_restart+0x40/0x80 arm64_sys_reboot+0x1b0/0x200 Fix this by adding cpus_read_lock()/cpus_read_unlock() to cpufreq_suspend() to block CPU hotplug operations while suspend is in progress. Fixes: 65650b35133f ("cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown") Signed-off-by: Tianxiang Chen Reviewed-by: Zhongqiu Han Cc: All applicable [ rjw: Changelog edits ] Link: https://patch.msgid.link/20260408141914.35281-1-nanmu@xiaomi.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/cpufreq/cpufreq.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1973,6 +1973,7 @@ void cpufreq_suspend(void) if (!cpufreq_driver) return; + cpus_read_lock(); if (!has_target() && !cpufreq_driver->suspend) goto suspend; @@ -1992,6 +1993,7 @@ void cpufreq_suspend(void) suspend: cpufreq_suspended = true; + cpus_read_unlock(); } /**