This is a note to let you know that I've just added the patch titled cpu/hotplug: Drop the device lock on error to the 4.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: cpu-hotplug-drop-the-device-lock-on-error.patch and it can be found in the queue-4.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 40da1b11f01e43aad1aa6cea64681b6125e8a2a7 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Date: Fri, 2 Jun 2017 16:27:14 +0200 Subject: cpu/hotplug: Drop the device lock on error From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> commit 40da1b11f01e43aad1aa6cea64681b6125e8a2a7 upstream. If a custom CPU target is specified and that one is not available _or_ can't be interrupted then the code returns to userland without dropping a lock as notices by lockdep: |echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target | ================================================ | [ BUG: lock held when returning to user space! ] | ------------------------------------------------ | bash/503 is leaving the kernel with locks still held! | 1 lock held by bash/503: | #0: (device_hotplug_lock){+.+...}, at: [<ffffffff815b5650>] lock_device_hotplug_sysfs+0x10/0x40 So release the lock then. Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20170602142714.3ogo25f2wbq6fjpj@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/cpu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1656,13 +1656,13 @@ static ssize_t write_cpuhp_target(struct ret = !sp->name || sp->cant_stop ? -EINVAL : 0; mutex_unlock(&cpuhp_state_mutex); if (ret) - return ret; + goto out; if (st->state < target) ret = do_cpu_up(dev->id, target); else ret = do_cpu_down(dev->id, target); - +out: unlock_device_hotplug(); return ret ? ret : count; } Patches currently in stable-queue which might be from bigeasy@xxxxxxxxxxxxx are queue-4.11/cpu-hotplug-drop-the-device-lock-on-error.patch