On Tue, Jun 22, 2021 at 02:47:57PM +1000, Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the rcu tree got a conflict in:
>
> kernel/rcu/tree_stall.h
>
> between commit:
>
> 2f064a59a11f ("sched: Change task_struct::state")
>
> from the tip tree and commit:
>
> 367455053a76 ("rcu: Mark accesses in tree_stall.h")
>
> from the rcu tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging. You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
I have moved this RCU commit out of my -next pile. I will put it back
at v5.14-rc1 time. The other conflict looks quite straightforward,
so I am leaving that one be.
Thanx, Paul
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc kernel/rcu/tree_stall.h
> index acb2288063b5,24065f1acb8b..000000000000
> --- a/kernel/rcu/tree_stall.h
> +++ b/kernel/rcu/tree_stall.h
> @@@ -460,12 -462,13 +462,13 @@@ static void rcu_check_gp_kthread_starva
>
> if (rcu_is_gp_kthread_starving(&j)) {
> cpu = gpk ? task_cpu(gpk) : -1;
> - pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#lx ->cpu=%d\n",
> + pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#x ->cpu=%d\n",
> rcu_state.name, j,
> (long)rcu_seq_current(&rcu_state.gp_seq),
> - data_race(rcu_state.gp_flags),
> - gp_state_getname(rcu_state.gp_state), rcu_state.gp_state,
> - gpk ? gpk->__state : ~0, cpu);
> + data_race(READ_ONCE(rcu_state.gp_flags)),
> + gp_state_getname(rcu_state.gp_state),
> + data_race(READ_ONCE(rcu_state.gp_state)),
> - gpk ? data_race(READ_ONCE(gpk->state)) : ~0, cpu);
> ++ gpk ? data_race(READ_ONCE(gpk->__state)) : ~0, cpu);
> if (gpk) {
> 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");
> @@@ -508,7 -511,7 +511,7 @@@ static void rcu_check_gp_kthread_expire
> (long)rcu_seq_current(&rcu_state.gp_seq),
> data_race(rcu_state.gp_flags),
> gp_state_getname(RCU_GP_WAIT_FQS), RCU_GP_WAIT_FQS,
> - gpk->__state);
> - data_race(READ_ONCE(gpk->state)));
> ++ data_race(READ_ONCE(gpk->__state)));
> pr_err("\tPossible timer handling issue on cpu=%d timer-softirq=%u\n",
> cpu, kstat_softirqs_cpu(TIMER_SOFTIRQ, cpu));
> }
> @@@ -732,23 -816,34 +816,34 @@@ void show_rcu_gp_kthreads(void
> struct task_struct *t = READ_ONCE(rcu_state.gp_kthread);
>
> j = jiffies;
> - ja = j - data_race(rcu_state.gp_activity);
> - jr = j - data_race(rcu_state.gp_req_activity);
> - jw = j - data_race(rcu_state.gp_wake_time);
> - pr_info("%s: wait state: %s(%d) ->state: %#x delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
> + ja = j - data_race(READ_ONCE(rcu_state.gp_activity));
> + jr = j - data_race(READ_ONCE(rcu_state.gp_req_activity));
> + js = j - data_race(READ_ONCE(rcu_state.gp_start));
> + jw = j - data_race(READ_ONCE(rcu_state.gp_wake_time));
> - pr_info("%s: wait state: %s(%d) ->state: %#lx ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
> ++ pr_info("%s: wait state: %s(%d) ->state: %#x ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
> rcu_state.name, gp_state_getname(rcu_state.gp_state),
> - rcu_state.gp_state, t ? t->__state : 0x1ffff,
> - ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
> - (long)data_race(rcu_state.gp_seq),
> - (long)data_race(rcu_get_root()->gp_seq_needed),
> - data_race(rcu_state.gp_flags));
> + data_race(READ_ONCE(rcu_state.gp_state)),
> - t ? data_race(READ_ONCE(t->state)) : 0x1ffffL, t ? t->rt_priority : 0xffU,
> ++ t ? data_race(READ_ONCE(t->__state)) : 0x1ffffL, t ? t->rt_priority : 0xffU,
> + js, ja, jr, jw, (long)data_race(READ_ONCE(rcu_state.gp_wake_seq)),
> + (long)data_race(READ_ONCE(rcu_state.gp_seq)),
> + (long)data_race(READ_ONCE(rcu_get_root()->gp_seq_needed)),
> + data_race(READ_ONCE(rcu_state.gp_max)),
> + data_race(READ_ONCE(rcu_state.gp_flags)));
> rcu_for_each_node_breadth_first(rnp) {
> - if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq),
> - READ_ONCE(rnp->gp_seq_needed)))
> + if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed)) &&
> + !data_race(READ_ONCE(rnp->qsmask)) && !data_race(READ_ONCE(rnp->boost_tasks)) &&
> + !data_race(READ_ONCE(rnp->exp_tasks)) && !data_race(READ_ONCE(rnp->gp_tasks)))
> continue;
> - pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n",
> - rnp->grplo, rnp->grphi, (long)data_race(rnp->gp_seq),
> - (long)data_race(rnp->gp_seq_needed));
> + pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n",
> + rnp->grplo, rnp->grphi,
> + (long)data_race(READ_ONCE(rnp->gp_seq)),
> + (long)data_race(READ_ONCE(rnp->gp_seq_needed)),
> + data_race(READ_ONCE(rnp->qsmask)),
> + ".b"[!!data_race(READ_ONCE(rnp->boost_kthread_task))],
> + ".B"[!!data_race(READ_ONCE(rnp->boost_tasks))],
> + ".E"[!!data_race(READ_ONCE(rnp->exp_tasks))],
> + ".G"[!!data_race(READ_ONCE(rnp->gp_tasks))],
> + data_race(READ_ONCE(rnp->n_boosts)));
> if (!rcu_is_leaf_node(rnp))
> continue;
> for_each_leaf_node_possible_cpu(rnp, cpu) {
