| Message ID | 20230712151557.760-3-thunder.leizhen@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 5df5ceeff840fdc9bfae4bfb530b8b7e05d7728e |
| Headers | show |
| Series | rcu: Don't dump the stalled CPU on where RCU GP kthread last ran twice | expand |
On Wed, Jul 12, 2023 at 11:15:57PM +0800, Zhen Lei wrote: > The stacks of all stalled CPUs will be dumped in rcu_dump_cpu_stacks(). > If the CPU on where RCU GP kthread last ran is stalled, its stack does > not need to be dumped again. We can search the corresponding backtrace > based on the printed CPU ID. > > For example: > [ 87.328275] rcu: rcu_sched kthread starved for ... ->cpu=3 <--------| > ... ... | > [ 89.385007] NMI backtrace for cpu 3 <--------| > [ 89.385179] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.10.0+ #22 <--| > [ 89.385188] Hardware name: linux,dummy-virt (DT) > [ 89.385196] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) > [ 89.385204] pc : arch_cpu_idle+0x40/0xc0 > [ 89.385211] lr : arch_cpu_idle+0x2c/0xc0 > ... ... > [ 89.385566] Call trace: > [ 89.385574] arch_cpu_idle+0x40/0xc0 > [ 89.385581] default_idle_call+0x100/0x450 > [ 89.385589] cpuidle_idle_call+0x2f8/0x460 > [ 89.385596] do_idle+0x1dc/0x3d0 > [ 89.385604] cpu_startup_entry+0x5c/0xb0 > [ 89.385613] secondary_start_kernel+0x35c/0x520 > > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> > Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> I queued both patches, thank you both! Thanx, Paul > --- > kernel/rcu/tree_stall.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h > index dcfaa3d5db2cbc7..cc884cd49e026a3 100644 > --- a/kernel/rcu/tree_stall.h > +++ b/kernel/rcu/tree_stall.h > @@ -534,12 +534,14 @@ static void rcu_check_gp_kthread_starvation(void) > data_race(READ_ONCE(rcu_state.gp_state)), > gpk ? data_race(READ_ONCE(gpk->__state)) : ~0, cpu); > if (gpk) { > + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); > + > pr_err("\tUnless %s kthread gets sufficient CPU time, OOM is now expected behavior.\n", rcu_state.name); > pr_err("RCU grace-period kthread stack dump:\n"); > sched_show_task(gpk); > if (cpu_is_offline(cpu)) { > pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu); > - } else { > + } else if (!(data_race(READ_ONCE(rdp->mynode->qsmask)) & rdp->grpmask)) { > pr_err("Stack dump where RCU GP kthread last ran:\n"); > dump_cpu_task(cpu); > } > -- > 2.25.1 >
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index dcfaa3d5db2cbc7..cc884cd49e026a3 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -534,12 +534,14 @@ static void rcu_check_gp_kthread_starvation(void) data_race(READ_ONCE(rcu_state.gp_state)), gpk ? data_race(READ_ONCE(gpk->__state)) : ~0, cpu); if (gpk) { + struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); + pr_err("\tUnless %s kthread gets sufficient CPU time, OOM is now expected behavior.\n", rcu_state.name); pr_err("RCU grace-period kthread stack dump:\n"); sched_show_task(gpk); if (cpu_is_offline(cpu)) { pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu); - } else { + } else if (!(data_race(READ_ONCE(rdp->mynode->qsmask)) & rdp->grpmask)) { pr_err("Stack dump where RCU GP kthread last ran:\n"); dump_cpu_task(cpu); }