topic Re: uevents causing kernel panic in i.MX Processors

uevents causing kernel panic

mathew_k_t — Tue, 22 May 2018 04:59:46 GMT

Hi,

I'm working with imx6ull custom board. In my BSP, I have enabled uevents for notifying interrupts to userspace application. I'm receiving uevents. But the uevents cause memory exhaust. It uses 500KB within 2sec.Verified with top command.

Finally, it enters to kernel panic after 30 minutes due to Out of Memory.

1. How to avoid this?

2. Is there any other method to receive events to userspace application other than uevents?(should capable of interrupts at every 5ms)?

Best Regards

Re: uevents causing kernel panic

Bio_TICFSL — Fri, 25 May 2018 14:41:57 GMT

Hi Mathew_k_t

Udev works by receiving uevents. But there is an option - kernel can call usermode helper. In this case kernel spawns one process per hotplug event, supplying environment variables to each new process describing that particular hotplug event. If you look at kobject_uevent_env you'll see that netlink message is actually #ifdefed and default action is to call that usermode helper.

Re: uevents causing kernel panic

mathew_k_t — Fri, 01 Jun 2018 06:28:56 GMT

Hi,

Thank you for your response.

I have tried udevd --debug and found the udev rules related to it. Then, I made some changes in those rules and I found no memory leak in the initial 40 minutes.

But after that the memory leak happens again and goes to panic within 1 hour 15 minutes. How to debug this issue?

Could you give more detail of usermode helper and how to handle it?