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Commit 319362c9 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Provide more diagnostics for stalled GP kthread 



Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent d770e558

kernel/rcu/tree.c

+8 −2
Original line number Diff line number Diff line
@@ -1178,9 +1178,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp) 
	j = jiffies;

	gpa = READ_ONCE(rsp->gp_activity);

	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->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,

						 READ_ONCE(rsp->gp_flags) &

						 RCU_GP_FLAG_INIT);

			rsp->gp_state = RCU_GP_DONE_GPS;

			/* Locking provides needed memory barrier. */

			if (rcu_gp_init(rsp))

				break;
@@ -2073,6 +2076,7 @@ static int __noreturn rcu_gp_kthread(void *arg) 
					(!READ_ONCE(rnp->qsmask) &&

					 !rcu_preempt_blocked_readers_cgp(rnp)),

					j);

			rsp->gp_state = RCU_GP_DONE_FQS;

			/* Locking provides needed memory barriers. */

			/* If grace period done, leave loop. */

			if (!READ_ONCE(rnp->qsmask) &&
@@ -2110,7 +2114,9 @@ static int __noreturn rcu_gp_kthread(void *arg) 
		}



		/* Handle grace-period end. */

		rsp->gp_state = RCU_GP_CLEANUP;

		rcu_gp_cleanup(rsp);

		rsp->gp_state = RCU_GP_CLEANED;

	}

}

kernel/rcu/tree.h

+5 −1
Original line number Diff line number Diff line
@@ -527,7 +527,11 @@ struct rcu_state { 
/* Values for rcu_state structure's gp_flags field. */

#define RCU_GP_WAIT_INIT 0	/* Initial state. */

#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;