On Fri, 24 Apr 2020 17:26:32 +0800 Xiao Yang <yangx.jy@xxxxxxxxxxxxxx> wrote: > Hi Steve, Joel > > Sorry to bother you. > > On my slow arm64 vm, inserting and removing preemptirq_delay_test module > in loops triggers kernel panic sometimes. > > Reproduce steps: > Do the following steps in loops(more than 10 times): > [root@CentOS81-aarch64 ]# modprobe preemptirq_delay_test > test_mode=preempt delay=500000; rmmod preemptirq_delay_test > > Joel, I never did really look at that module, but doing a quick scan, I see you never clean up the task you start. Which means, you can remove the module and the task still exists, and when it runs, it will execute code that has been freed. The module exit should still do a kthread_stop() on it. If anything, it will prevent the task existing after the module is removed. -- Steve
