From: Tianxiang Chen Date: Wed, 8 Apr 2026 14:19:14 +0000 (+0800) Subject: cpufreq: Fix hotplug-suspend race during reboot X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=a9029dd55696c651ee46912afa2a166fa456bb3e;p=thirdparty%2Fkernel%2Flinux.git cpufreq: Fix hotplug-suspend race during reboot 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 --- diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 44eb1b7e7fc1b..d41067cd1f1b2 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1972,6 +1972,7 @@ void cpufreq_suspend(void) if (!cpufreq_driver) return; + cpus_read_lock(); if (!has_target() && !cpufreq_driver->suspend) goto suspend; @@ -1991,6 +1992,7 @@ void cpufreq_suspend(void) suspend: cpufreq_suspended = true; + cpus_read_unlock(); } /**