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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-05-08 23:18:57 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-07-13 00:39:09 +0200 |
| commit | 577389423187d8b51dfe6199297e579a3419b72b (patch) | |
| tree | 8cb47b71dc71d38c6f36f698281bf8a05b929393 /kernel/rcu/tree.c | |
| parent | rcu: Add up-tree information to dump_blkd_tasks() diagnostics (diff) | |
| download | linux-577389423187d8b51dfe6199297e579a3419b72b.tar.xz linux-577389423187d8b51dfe6199297e579a3419b72b.zip | |
rcu: Add CPU online/offline state to dump_blkd_tasks()
Interactions between CPU-hotplug operations and grace-period
initialization can result in dump_blkd_tasks(). One of the first
debugging actions in this case is to search back in dmesg to work
out which of the affected rcu_node structure's CPUs are online and to
determine the last CPU-hotplug operation affecting any of those CPUs.
This can be laborious and error-prone, especially when console output
is lost.
This commit therefore causes dump_blkd_tasks() to dump the state of
the affected rcu_node structure's CPUs and the last grace period during
which the last offline and online operation affected each of these CPUs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.c')
| -rw-r--r-- | kernel/rcu/tree.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5f1a11f1f7bc..a2503ef1bbe2 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1954,7 +1954,7 @@ static bool rcu_gp_init(struct rcu_state *rsp) rcu_gp_slow(rsp, gp_init_delay); raw_spin_lock_irqsave_rcu_node(rnp, flags); rdp = this_cpu_ptr(rsp->rda); - rcu_preempt_check_blocked_tasks(rnp); + rcu_preempt_check_blocked_tasks(rsp, rnp); rnp->qsmask = rnp->qsmaskinit; WRITE_ONCE(rnp->gp_seq, rsp->gp_seq); if (rnp == rdp->mynode) @@ -2063,7 +2063,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp) rcu_for_each_node_breadth_first(rsp, rnp) { raw_spin_lock_irq_rcu_node(rnp); if (WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp))) - dump_blkd_tasks(rnp, 10); + dump_blkd_tasks(rsp, rnp, 10); WARN_ON_ONCE(rnp->qsmask); WRITE_ONCE(rnp->gp_seq, new_gp_seq); rdp = this_cpu_ptr(rsp->rda); @@ -3516,6 +3516,10 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) rdp->dynticks = &per_cpu(rcu_dynticks, cpu); WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1); WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks))); + rdp->rcu_ofl_gp_seq = rsp->gp_seq; + rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED; + rdp->rcu_onl_gp_seq = rsp->gp_seq; + rdp->rcu_onl_gp_flags = RCU_GP_CLEANED; rdp->cpu = cpu; rdp->rsp = rsp; rcu_boot_init_nocb_percpu_data(rdp); @@ -3711,6 +3715,8 @@ void rcu_cpu_starting(unsigned int cpu) /* Allow lockless access for expedited grace periods. */ smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */ rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */ + rdp->rcu_onl_gp_seq = READ_ONCE(rsp->gp_seq); + rdp->rcu_onl_gp_flags = READ_ONCE(rsp->gp_flags); if (rnp->qsmask & mask) { /* RCU waiting on incoming CPU? */ /* Report QS -after- changing ->qsmaskinitnext! */ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags); @@ -3738,6 +3744,8 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp) mask = rdp->grpmask; spin_lock(&rsp->ofl_lock); raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */ + rdp->rcu_ofl_gp_seq = READ_ONCE(rsp->gp_seq); + rdp->rcu_ofl_gp_flags = READ_ONCE(rsp->gp_flags); if (rnp->qsmask & mask) { /* RCU waiting on outgoing CPU? */ /* Report quiescent state -before- changing ->qsmaskinitnext! */ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags); |