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rcu: Provide more diagnostics for stalled GP kthread

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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2015-05-19 14:16:52 -07:00
parent d770e558e2
commit 319362c90f
2 changed files with 13 additions and 3 deletions
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10
kernel/rcu/tree.c
View File

@ -1178,9 +1178,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
j = jiffies; j = jiffies;
gpa = READ_ONCE(rsp->gp_activity); gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ) if (j - gpa > 2 * HZ)
pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x\n", pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n",
rsp->name, j - gpa, rsp->name, j - gpa,
rsp->gpnum, rsp->completed, rsp->gp_flags); rsp->gpnum, rsp->completed,
rsp->gp_flags, rsp->gp_state,
rsp->gp_kthread ? rsp->gp_kthread->state : 0);
} }
/* /*
@ -2041,6 +2043,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
wait_event_interruptible(rsp->gp_wq, wait_event_interruptible(rsp->gp_wq,
READ_ONCE(rsp->gp_flags) & READ_ONCE(rsp->gp_flags) &
RCU_GP_FLAG_INIT); RCU_GP_FLAG_INIT);
rsp->gp_state = RCU_GP_DONE_GPS;
/* Locking provides needed memory barrier. */ /* Locking provides needed memory barrier. */
if (rcu_gp_init(rsp)) if (rcu_gp_init(rsp))
break; break;
@ -2073,6 +2076,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
(!READ_ONCE(rnp->qsmask) && (!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp)), !rcu_preempt_blocked_readers_cgp(rnp)),
j); j);
rsp->gp_state = RCU_GP_DONE_FQS;
/* Locking provides needed memory barriers. */ /* Locking provides needed memory barriers. */
/* If grace period done, leave loop. */ /* If grace period done, leave loop. */
if (!READ_ONCE(rnp->qsmask) && if (!READ_ONCE(rnp->qsmask) &&
@ -2110,7 +2114,9 @@ static int __noreturn rcu_gp_kthread(void *arg)
} }
/* Handle grace-period end. */ /* Handle grace-period end. */
rsp->gp_state = RCU_GP_CLEANUP;
rcu_gp_cleanup(rsp); rcu_gp_cleanup(rsp);
rsp->gp_state = RCU_GP_CLEANED;
} }
} }

6
kernel/rcu/tree.h
View File

@ -527,7 +527,11 @@ struct rcu_state {
/* Values for rcu_state structure's gp_flags field. */ /* Values for rcu_state structure's gp_flags field. */
#define RCU_GP_WAIT_INIT 0 /* Initial state. */ #define RCU_GP_WAIT_INIT 0 /* Initial state. */
#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
#define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */ #define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */
#define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */
#define RCU_GP_DONE_FQS 4 /* Wait done for force-quiescent-state time. */
#define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
#define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
extern struct list_head rcu_struct_flavors; extern struct list_head rcu_struct_flavors;