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rcutorture: Recover from OOM during forward-progress tests
This commit causes the OOM handler to do rcu_barrier() calls and to free up forward-progress callbacks in order to recover from OOM events. The current test is terminated, but subsequent forward-progress tests can proceed. This allows a long test to result in multiple forward-progress failures, greatly reducing the required testing time. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
This commit is contained in:
parent
73d665b141
commit
2667ccce93
1 changed files with 49 additions and 11 deletions
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@ -1649,13 +1649,14 @@ static void rcu_torture_fwd_cb_hist(void)
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/* Callback function for continuous-flood RCU callbacks. */
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static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
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{
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unsigned long flags;
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int i;
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struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
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struct rcu_fwd_cb **rfcpp;
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rfcp->rfc_next = NULL;
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rfcp->rfc_gps++;
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spin_lock(&rcu_fwd_lock);
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spin_lock_irqsave(&rcu_fwd_lock, flags);
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rfcpp = rcu_fwd_cb_tail;
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rcu_fwd_cb_tail = &rfcp->rfc_next;
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WRITE_ONCE(*rfcpp, rfcp);
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@ -1664,7 +1665,33 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
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if (i >= ARRAY_SIZE(n_launders_hist))
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i = ARRAY_SIZE(n_launders_hist) - 1;
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n_launders_hist[i]++;
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spin_unlock(&rcu_fwd_lock);
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spin_unlock_irqrestore(&rcu_fwd_lock, flags);
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}
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/*
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* Free all callbacks on the rcu_fwd_cb_head list, either because the
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* test is over or because we hit an OOM event.
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*/
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static unsigned long rcu_torture_fwd_prog_cbfree(void)
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{
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unsigned long flags;
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unsigned long freed = 0;
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struct rcu_fwd_cb *rfcp;
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for (;;) {
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spin_lock_irqsave(&rcu_fwd_lock, flags);
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rfcp = rcu_fwd_cb_head;
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if (!rfcp)
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break;
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rcu_fwd_cb_head = rfcp->rfc_next;
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if (!rcu_fwd_cb_head)
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rcu_fwd_cb_tail = &rcu_fwd_cb_head;
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spin_unlock_irqrestore(&rcu_fwd_lock, flags);
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kfree(rfcp);
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freed++;
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}
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spin_unlock_irqrestore(&rcu_fwd_lock, flags);
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return freed;
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}
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/* Carry out need_resched()/cond_resched() forward-progress testing. */
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@ -1743,6 +1770,9 @@ static void rcu_torture_fwd_prog_cr(void)
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unsigned long stopat;
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unsigned long stoppedat;
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if (READ_ONCE(rcu_fwd_emergency_stop))
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return; /* Get out of the way quickly, no GP wait! */
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/* Loop continuously posting RCU callbacks. */
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WRITE_ONCE(rcu_fwd_cb_nodelay, true);
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cur_ops->sync(); /* Later readers see above write. */
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@ -1788,16 +1818,10 @@ static void rcu_torture_fwd_prog_cr(void)
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cver = READ_ONCE(rcu_torture_current_version) - cver;
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gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
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cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
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for (;;) {
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rfcp = rcu_fwd_cb_head;
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if (!rfcp)
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break;
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rcu_fwd_cb_head = rfcp->rfc_next;
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kfree(rfcp);
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}
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rcu_fwd_cb_tail = &rcu_fwd_cb_head;
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(void)rcu_torture_fwd_prog_cbfree();
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WRITE_ONCE(rcu_fwd_cb_nodelay, false);
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if (!torture_must_stop()) {
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if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
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WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
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pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
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__func__,
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@ -1817,9 +1841,23 @@ static void rcu_torture_fwd_prog_cr(void)
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static int rcutorture_oom_notify(struct notifier_block *self,
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unsigned long notused, void *nfreed)
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{
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WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
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__func__);
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rcu_torture_fwd_cb_hist();
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rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2));
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WRITE_ONCE(rcu_fwd_emergency_stop, true);
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smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
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pr_info("%s: Freed %lu RCU callbacks.\n",
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__func__, rcu_torture_fwd_prog_cbfree());
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rcu_barrier();
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pr_info("%s: Freed %lu RCU callbacks.\n",
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__func__, rcu_torture_fwd_prog_cbfree());
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rcu_barrier();
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pr_info("%s: Freed %lu RCU callbacks.\n",
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__func__, rcu_torture_fwd_prog_cbfree());
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smp_mb(); /* Frees before return to avoid redoing OOM. */
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(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
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pr_info("%s returning after OOM processing.\n", __func__);
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return NOTIFY_OK;
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}
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