From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: [PATCH tip/core/rcu 4/9] rcutorture: Emulate dyntick aspect of userspace nohz_full sojourn
Date: Wed, 2 Oct 2019 18:47:23 -0700 [thread overview]
Message-ID: <20191003014728.13496-4-paulmck@kernel.org> (raw)
In-Reply-To: <20191003014710.GA13323@paulmck-ThinkPad-P72>
From: "Paul E. McKenney" <paulmck@linux.ibm.com>
During an actual call_rcu() flood, there would be frequent trips to
userspace (in-kernel call_rcu() floods must be otherwise housebroken).
Userspace execution on nohz_full CPUs implies an RCU dyntick idle/not-idle
transition pair, so this commit adds emulation of that pair.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
include/linux/rcutiny.h | 1 +
kernel/rcu/rcutorture.c | 11 +++++++++++
kernel/rcu/tree.c | 1 +
3 files changed, 13 insertions(+)
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 9bf1dfe..37b6f0c 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -84,6 +84,7 @@ static inline void rcu_scheduler_starting(void) { }
#endif /* #else #ifndef CONFIG_SRCU */
static inline void rcu_end_inkernel_boot(void) { }
static inline bool rcu_is_watching(void) { return true; }
+static inline void rcu_momentary_dyntick_idle(void) { }
/* Avoid RCU read-side critical sections leaking across. */
static inline void rcu_all_qs(void) { barrier(); }
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 3c9feca..7dcb2b8 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1759,6 +1759,11 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void)
kfree(rfcp);
freed++;
rcu_torture_fwd_prog_cond_resched(freed);
+ if (tick_nohz_full_enabled()) {
+ local_irq_save(flags);
+ rcu_momentary_dyntick_idle();
+ local_irq_restore(flags);
+ }
}
return freed;
}
@@ -1833,6 +1838,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
static void rcu_torture_fwd_prog_cr(void)
{
unsigned long cver;
+ unsigned long flags;
unsigned long gps;
int i;
long n_launders;
@@ -1891,6 +1897,11 @@ static void rcu_torture_fwd_prog_cr(void)
}
cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
+ if (tick_nohz_full_enabled()) {
+ local_irq_save(flags);
+ rcu_momentary_dyntick_idle();
+ local_irq_restore(flags);
+ }
}
stoppedat = jiffies;
n_launders_cb_snap = READ_ONCE(n_launders_cb);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8110514..5692db5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -375,6 +375,7 @@ static void __maybe_unused rcu_momentary_dyntick_idle(void)
WARN_ON_ONCE(!(special & RCU_DYNTICK_CTRL_CTR));
rcu_preempt_deferred_qs(current);
}
+EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle);
/**
* rcu_is_cpu_rrupt_from_idle - see if interrupted from idle
--
2.9.5
next prev parent reply other threads:[~2019-10-03 1:47 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-03 1:47 [PATCH tip/core/rcu 0/9] Torture-test updates Paul E. McKenney
2019-10-03 1:47 ` [PATCH tip/core/rcu 1/9] rcu: Remove unused function rcutorture_record_progress() paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 2/9] locktorture: Replace strncmp() with str_has_prefix() paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 3/9] rcutorture: Remove CONFIG_HOTPLUG_CPU=n from scenarios paulmck
2019-10-03 1:47 ` paulmck [this message]
2019-10-03 1:47 ` [PATCH tip/core/rcu 5/9] rcu: Remove unused variable rcu_perf_writer_state paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 6/9] rcutorture: Separate warnings for each failure type paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 7/9] rcutorture: Make in-kernel-loop testing more brutal paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 8/9] locking: locktorture: Do not include rwlock.h directly paulmck
2019-10-03 1:47 ` [PATCH tip/core/rcu 9/9] rcu: Suppress levelspread uninitialized messages paulmck
2019-10-03 8:53 ` Geert Uytterhoeven
2019-10-05 16:16 ` Paul E. McKenney
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