Messages in this thread Patch in this message | | | From | Satya Durga Srinivasu Prabhala <> | Subject | [PATCH] sched: fix rq lock recursion issue | Date | Fri, 24 Jun 2022 00:42:40 -0700 |
| |
Below recursion is observed in a rare scenario where __schedule() takes rq lock, at around same time task's affinity is being changed, bpf function for tracing sched_switch calls migrate_enabled(), checks for affinity change (cpus_ptr != cpus_mask) lands into __set_cpus_allowed_ptr which tries acquire rq lock and causing the recursion bug.
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) -016 |__schedule(sched_mode = ?) -017 |schedule() -018 |arch_local_save_flags(inline) -018 |arch_irqs_disabled(inline) -018 |__raw_spin_lock_irq(inline) -018 |_raw_spin_lock_irq(inline) -018 |worker_thread(__worker = 0xFFFFFF88CE251300) -019 |kthread(_create = 0xFFFFFF88730A5A80) -020 |ret_from_fork(asm)
Signed-off-by: Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com> --- kernel/sched/core.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index bfa7452ca92e..e254e9227341 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2223,6 +2223,7 @@ static void migrate_disable_switch(struct rq *rq, struct task_struct *p) void migrate_disable(void) { +#ifdef CONFIG_PREEMPT_RT struct task_struct *p = current; if (p->migration_disabled) { @@ -2234,11 +2235,15 @@ void migrate_disable(void) this_rq()->nr_pinned++; p->migration_disabled = 1; preempt_enable(); +#else + preempt_disable(); +#endif } EXPORT_SYMBOL_GPL(migrate_disable); void migrate_enable(void) { +#ifdef CONFIG_PREEMPT_RT struct task_struct *p = current; if (p->migration_disabled > 1) { @@ -2265,6 +2270,9 @@ void migrate_enable(void) p->migration_disabled = 0; this_rq()->nr_pinned--; preempt_enable(); +#else + preempt_enable(); +#endif } EXPORT_SYMBOL_GPL(migrate_enable); -- 2.36.1
| |