On 29/03/2022 14:59, Lukasz Luba wrote:
On 3/25/22 09:44, Kant Fan wrote:
commit 7b62935828266658714f81d4e9176edad808dc70 upstream.
Fix access illegal address problem in following condition: There are muti devfreq cooling devices in system, some of them register with dfc_power but other does not, power model ops such as state2power will append to global devfreq_cooling_ops when the cooling device with dfc_power register. It makes the cooling device without dfc_power also use devfreq_cooling_ops after appending when register later by of_devfreq_cooling_register_power() or of_devfreq_cooling_register().
IPA governor regards the cooling devices without dfc_power as a power actor because they also have power model ops, and will access illegal address at dfc->power_ops when execute cdev->ops->get_requested_power or cdev->ops->power2state. As the calltrace below shows:
Unable to handle kernel NULL pointer dereference at virtual address 00000008 ... calltrace: [<c06e5488>] devfreq_cooling_power2state+0x24/0x184 [<c06df420>] power_actor_set_power+0x54/0xa8 [<c06e3774>] power_allocator_throttle+0x770/0x97c [<c06dd120>] handle_thermal_trip+0x1b4/0x26c [<c06ddb48>] thermal_zone_device_update+0x154/0x208 [<c014159c>] process_one_work+0x1ec/0x36c [<c0141c58>] worker_thread+0x204/0x2ec [<c0146788>] kthread+0x140/0x154 [<c01010e8>] ret_from_fork+0x14/0x2c
Fixes: a76caf55e5b35 ("thermal: Add devfreq cooling") Cc: stable@vger.kernel.org # 4.4+ Signed-off-by: Kant Fan kant@allwinnertech.com
drivers/thermal/devfreq_cooling.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)
Looks good. So this patch should be applied for all stable kernels starting from v4.4 to v5.12 (the v5.13 and later need other patch).
Next time you might use in the subject something like: [PATCH 4.4] thermal: devfreq_cooling: use local ops instead of global ops It would be better distinguished from your other patch with the same subject, which was for mainline and v5.13+
Hi Lukasz, Thank you for the guidance. I want to know if I'm understanding you in a right way. Could you confirm the following information?
1. The stable patches After the patch is merged into mainline later, I'll submit the following patches individually for v4.4 ~ v5.12:
[PATCH 4.4] thermal: devfreq_cooling: use local ops instead of global ops [PATCH 4.5] thermal: devfreq_cooling: use local ops instead of global ops ... [PATCH 5.12] thermal: devfreq_cooling: use local ops instead of global ops
And also the following patches individually for v5.13+ : [PATCH 5.13] thermal: devfreq_cooling: use local ops instead of global ops [PATCH 5.14] thermal: devfreq_cooling: use local ops instead of global ops ... [PATCH 5.17] thermal: devfreq_cooling: use local ops instead of global ops
2. The mainline patch I saw your mail with Rafael, seems there are conflicts... I wonder if there's anything wrong with my patch, or anything I can help?