Messages in this thread | | | Subject | Re: [PATCH] sched: fix rq lock recursion issue | From | Satya Durga Srinivasu Prabhala <> | Date | Tue, 5 Jul 2022 20:44:09 -0700 |
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On 7/1/22 8:54 AM, Steven Rostedt wrote: > 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()? I'm not sure, why we have migrate_disable/enable(). I will need to cross check further.
> > 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(). Thanks for the inputs. I still need to cross check and find a better way to repro the issue to be able to comment further. Will cross check on your suggestion.
> > -- Steve
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