On Mon, Dec 18, 2017 at 04:31:42PM +0800, Chunyan Zhang wrote:
> From: Vincent Wang <vincent.w...@spreadtrum.com>
>
> list_del_rcu() should be used to replace list_del() in the function
> _remove_list_dev(), since the opp is a rcu protected pointer.
>
> For example, on an ARM big.Little platform of spreadtrum, there are
> little cluster, big cluster and gpu using pm_opp. And the opp_table
> of big cluster will be removed when big cluster is removed, which
> is implemented in the cpufreq driver. Sometimes an issue maybe occur:
>
> [ 237.647758] c0 Unable to handle kernel paging request at virtual address
> dead000000000110
> [ 237.647776] c0 pgd = ffffffc073e78000
> [ 237.647786] c0 [dead000000000110] *pgd=0000000000000000,
> *pud=0000000000000000
> [ 237.647808] c0 Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [ 237.653535] c0 Modules linked in: sprdwl_ng(O) mtty marlin2_fm
> mali_kbase(O)
> [ 237.653569] c0 CPU: 0 PID: 38 Comm: kworker/u12:1 Tainted: G S W O
> 4.4.83+ #1
> [ 237.653578] c0 Hardware name: Spreadtrum SP9850KHsmt 1h10 Board (DT)
> [ 237.653594] c0 Workqueue: devfreq_wq devfreq_monitor
> [ 237.653605] c0 task: ffffffc0babd0d80 task.stack: ffffffc0badbc000
> [ 237.653619] c0 PC is at _find_device_opp+0x58/0xac
> [ 237.653629] c0 LR is at dev_pm_opp_find_freq_ceil+0x2c/0xb8
>
> [ 237.921294] c0 Call trace:
> [ 237.921425] c0 [<ffffff80085362b0>] _find_device_opp+0x58/0xac
> [ 237.921437] c0 [<ffffff8008536560>] dev_pm_opp_find_freq_ceil+0x2c/0xb8
> [ 237.921452] c0 [<ffffff80088760f4>] devfreq_recommended_opp+0x54/0x7c
> [ 237.921494] c0 [<ffffff8000b6a96c>] kbase_wait_write_flush+0x164/0x358
> [mali_kbase]
> [ 237.921504] c0 [<ffffff800887485c>] update_devfreq+0x8c/0xf8
> [ 237.921514] c0 [<ffffff80088749e4>] devfreq_monitor+0x34/0x94
> [ 237.921529] c0 [<ffffff80080bd75c>] process_one_work+0x154/0x458
> [ 237.921539] c0 [<ffffff80080be428>] worker_thread+0x134/0x4a4
> [ 237.921551] c0 [<ffffff80080c4bec>] kthread+0xdc/0xf0
> [ 237.921564] c0 [<ffffff8008085f20>] ret_from_fork+0x10/0x30
>
> Cc: stable <sta...@vger.kernel.org> # 4.4
> Signed-off-by: Vincent Wang <vincent.w...@spreadtrum.com>
> Signed-off-by: Chunyan Zhang <chunyan.zh...@spreadtrum.com>
> ---
>
> This patch is only for 4.4 stable branch.
> Once this patch accepted, I can cook a similar patch for 4.9 stable branch.
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
