diff options
| author | Tianxiang Chen <nanmu@xiaomi.com> | 2026-04-08 17:19:14 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2026-05-21 18:17:16 +0300 |
| commit | a9029dd55696c651ee46912afa2a166fa456bb3e (patch) | |
| tree | c4d2d74096a3f647aafbf9f06680f5eda52d6146 | |
| parent | 266d3dd8b757b48a576e90f018b51f7b7563cc32 (diff) | |
| download | linux-a9029dd55696c651ee46912afa2a166fa456bb3e.tar.xz | |
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 <nanmu@xiaomi.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
[ rjw: Changelog edits ]
Link: https://patch.msgid.link/20260408141914.35281-1-nanmu@xiaomi.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 44eb1b7e7fc1..d41067cd1f1b 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(); } /** |