Messages in this thread | | | Date | Fri, 1 Jul 2022 11:54:53 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] sched: fix rq lock recursion issue |
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On Thu, 30 Jun 2022 18:37:04 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> > > > Fix the issue by switching to preempt_enable/disable() for non-RT > > Kernels. > > > > -010 |spin_bug(lock = ???, msg = ???) > > -011 |debug_spin_lock_before(inline) > > -011 |do_raw_spin_lock(lock = 0xFFFFFF89323BB600) > > -012 |_raw_spin_lock(inline) > > -012 |raw_spin_rq_lock_nested(inline) > > -012 |raw_spin_rq_lock(inline) > > -012 |task_rq_lock(p = 0xFFFFFF88CFF1DA00, rf = 0xFFFFFFC03707BBE8) > > -013 |__set_cpus_allowed_ptr(inline) > > -013 |migrate_enable() > > -014 |trace_call_bpf(call = ?, ctx = 0xFFFFFFFDEF954600) > > -015 |perf_trace_run_bpf_submit(inline) > > -015 |perf_trace_sched_switch(__data = 0xFFFFFFE82CF0BCB8, preempt = FALSE, prev = ?, next = ?) > > -016 |__traceiter_sched_switch(inline) > > -016 |trace_sched_switch(inline) > > trace_sched_switch() disables preemption. > > So how is this a fix?
Let me rephrase my question.
As trace_sched_switch() disables preemption, why is trace_call_bpf() calling migrate_disable()?
Looks like you could modify the code to include a __bpf_prog_run_array() that skips the migrate_disable(). You even have a "cant_sleep()" call in trace_call_bpf().
-- Steve
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