Commit 4300aa642cc9ecb35f2e0683dd294fb790ef028c
1 parent
26845c2860
rcu: improve RCU CPU stall-warning messages
The existing RCU CPU stall-warning messages can be confusing, especially in the case where one CPU detects a single other stalled CPU. In addition, the console messages did not say which flavor of RCU detected the stall, which can make it difficult to work out exactly what is causing the stall. This commit improves these messages. Requested-by: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Showing 2 changed files with 12 additions and 9 deletions Side-by-side Diff
kernel/rcutree.c
| ... | ... | @@ -54,8 +54,8 @@ |
| 54 | 54 | |
| 55 | 55 | static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; |
| 56 | 56 | |
| 57 | -#define RCU_STATE_INITIALIZER(name) { \ | |
| 58 | - .level = { &name.node[0] }, \ | |
| 57 | +#define RCU_STATE_INITIALIZER(structname) { \ | |
| 58 | + .level = { &structname.node[0] }, \ | |
| 59 | 59 | .levelcnt = { \ |
| 60 | 60 | NUM_RCU_LVL_0, /* root of hierarchy. */ \ |
| 61 | 61 | NUM_RCU_LVL_1, \ |
| 62 | 62 | |
| 63 | 63 | |
| 64 | 64 | |
| ... | ... | @@ -66,13 +66,14 @@ |
| 66 | 66 | .signaled = RCU_GP_IDLE, \ |
| 67 | 67 | .gpnum = -300, \ |
| 68 | 68 | .completed = -300, \ |
| 69 | - .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&name.onofflock), \ | |
| 69 | + .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ | |
| 70 | 70 | .orphan_cbs_list = NULL, \ |
| 71 | - .orphan_cbs_tail = &name.orphan_cbs_list, \ | |
| 71 | + .orphan_cbs_tail = &structname.orphan_cbs_list, \ | |
| 72 | 72 | .orphan_qlen = 0, \ |
| 73 | - .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&name.fqslock), \ | |
| 73 | + .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ | |
| 74 | 74 | .n_force_qs = 0, \ |
| 75 | 75 | .n_force_qs_ngp = 0, \ |
| 76 | + .name = #structname, \ | |
| 76 | 77 | } |
| 77 | 78 | |
| 78 | 79 | struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state); |
| ... | ... | @@ -483,7 +484,8 @@ |
| 483 | 484 | |
| 484 | 485 | /* OK, time to rat on our buddy... */ |
| 485 | 486 | |
| 486 | - printk(KERN_ERR "INFO: RCU detected CPU stalls:"); | |
| 487 | + printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {", | |
| 488 | + rsp->name); | |
| 487 | 489 | rcu_for_each_leaf_node(rsp, rnp) { |
| 488 | 490 | raw_spin_lock_irqsave(&rnp->lock, flags); |
| 489 | 491 | rcu_print_task_stall(rnp); |
| ... | ... | @@ -494,7 +496,7 @@ |
| 494 | 496 | if (rnp->qsmask & (1UL << cpu)) |
| 495 | 497 | printk(" %d", rnp->grplo + cpu); |
| 496 | 498 | } |
| 497 | - printk(" (detected by %d, t=%ld jiffies)\n", | |
| 499 | + printk("} (detected by %d, t=%ld jiffies)\n", | |
| 498 | 500 | smp_processor_id(), (long)(jiffies - rsp->gp_start)); |
| 499 | 501 | trigger_all_cpu_backtrace(); |
| 500 | 502 | |
| ... | ... | @@ -510,8 +512,8 @@ |
| 510 | 512 | unsigned long flags; |
| 511 | 513 | struct rcu_node *rnp = rcu_get_root(rsp); |
| 512 | 514 | |
| 513 | - printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n", | |
| 514 | - smp_processor_id(), jiffies - rsp->gp_start); | |
| 515 | + printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", | |
| 516 | + rsp->name, smp_processor_id(), jiffies - rsp->gp_start); | |
| 515 | 517 | trigger_all_cpu_backtrace(); |
| 516 | 518 | |
| 517 | 519 | raw_spin_lock_irqsave(&rnp->lock, flags); |
kernel/rcutree.h
| ... | ... | @@ -326,6 +326,7 @@ |
| 326 | 326 | unsigned long jiffies_stall; /* Time at which to check */ |
| 327 | 327 | /* for CPU stalls. */ |
| 328 | 328 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ |
| 329 | + char *name; /* Name of structure. */ | |
| 329 | 330 | }; |
| 330 | 331 | |
| 331 | 332 | /* Return values for rcu_preempt_offline_tasks(). */ |