From: Joel Fernandes <joelaf@google.com>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
stable@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
Byungchul Park <byungchul.park@lge.com>,
Erick Reyes <erickreyes@google.com>,
Ingo Molnar <mingo@redhat.com>, Julia Cartwright <julia@ni.com>,
linux-kselftest@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Namhyung Kim <namhyung@kernel.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Shuah Khan <shuah@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Glexiner <tglx@linutronix.de>,
Todd Kjos <tkjos@google.com>,
Tom Zanussi <tom.zanussi@linux.intel.com>
Subject: [PATCH v7 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat
Date: Wed, 23 May 2018 18:21:50 -0700 [thread overview]
Message-ID: <20180524012157.181277-2-joel@joelfernandes.org> (raw)
In-Reply-To: <20180524012157.181277-1-joel@joelfernandes.org>
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
I'm able to reproduce a lockdep splat with config options:
CONFIG_PROVE_LOCKING=y,
CONFIG_DEBUG_LOCK_ALLOC=y and
CONFIG_PREEMPTIRQ_EVENTS=y
$ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable
[ 26.112609] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled)
[ 26.112636] WARNING: CPU: 0 PID: 118 at kernel/locking/lockdep.c:3854
[...]
[ 26.144229] Call Trace:
[ 26.144926] <IRQ>
[ 26.145506] lock_acquire+0x55/0x1b0
[ 26.146499] ? __do_softirq+0x46f/0x4d9
[ 26.147571] ? __do_softirq+0x46f/0x4d9
[ 26.148646] trace_preempt_on+0x8f/0x240
[ 26.149744] ? trace_preempt_on+0x4d/0x240
[ 26.150862] ? __do_softirq+0x46f/0x4d9
[ 26.151930] preempt_count_sub+0x18a/0x1a0
[ 26.152985] __do_softirq+0x46f/0x4d9
[ 26.153937] irq_exit+0x68/0xe0
[ 26.154755] smp_apic_timer_interrupt+0x271/0x280
[ 26.156056] apic_timer_interrupt+0xf/0x20
[ 26.157105] </IRQ>
The issue was this:
preempt_count = 1 << SOFTIRQ_SHIFT
__local_bh_enable(cnt = 1 << SOFTIRQ_SHIFT) {
if (softirq_count() == (cnt && SOFTIRQ_MASK)) {
trace_softirqs_on() {
current->softirqs_enabled = 1;
}
}
preempt_count_sub(cnt) {
trace_preempt_on() {
tracepoint() {
rcu_read_lock_sched() {
// jumps into lockdep
Where preempt_count still has softirqs disabled, but
current->softirqs_enabled is true, and we get a splat.
Cc: stable@vger.kernel.org
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fixes: d59158162e032 ("tracing: Add support for preempt and irq enable/disable events")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
kernel/softirq.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 177de3640c78..8a040bcaa033 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt)
{
lockdep_assert_irqs_disabled();
+ if (preempt_count() == cnt)
+ trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
+
if (softirq_count() == (cnt & SOFTIRQ_MASK))
trace_softirqs_on(_RET_IP_);
- preempt_count_sub(cnt);
+
+ __preempt_count_sub(cnt);
}
/*
--
2.17.0.441.gb46fe60e1d-goog
WARNING: multiple messages have this Message-ID
From: joelaf at google.com (Joel Fernandes)
Subject: [PATCH v7 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat
Date: Wed, 23 May 2018 18:21:50 -0700 [thread overview]
Message-ID: <20180524012157.181277-2-joel@joelfernandes.org> (raw)
In-Reply-To: <20180524012157.181277-1-joel@joelfernandes.org>
From: "Joel Fernandes (Google)" <joel at joelfernandes.org>
I'm able to reproduce a lockdep splat with config options:
CONFIG_PROVE_LOCKING=y,
CONFIG_DEBUG_LOCK_ALLOC=y and
CONFIG_PREEMPTIRQ_EVENTS=y
$ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable
[ 26.112609] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled)
[ 26.112636] WARNING: CPU: 0 PID: 118 at kernel/locking/lockdep.c:3854
[...]
[ 26.144229] Call Trace:
[ 26.144926] <IRQ>
[ 26.145506] lock_acquire+0x55/0x1b0
[ 26.146499] ? __do_softirq+0x46f/0x4d9
[ 26.147571] ? __do_softirq+0x46f/0x4d9
[ 26.148646] trace_preempt_on+0x8f/0x240
[ 26.149744] ? trace_preempt_on+0x4d/0x240
[ 26.150862] ? __do_softirq+0x46f/0x4d9
[ 26.151930] preempt_count_sub+0x18a/0x1a0
[ 26.152985] __do_softirq+0x46f/0x4d9
[ 26.153937] irq_exit+0x68/0xe0
[ 26.154755] smp_apic_timer_interrupt+0x271/0x280
[ 26.156056] apic_timer_interrupt+0xf/0x20
[ 26.157105] </IRQ>
The issue was this:
preempt_count = 1 << SOFTIRQ_SHIFT
__local_bh_enable(cnt = 1 << SOFTIRQ_SHIFT) {
if (softirq_count() == (cnt && SOFTIRQ_MASK)) {
trace_softirqs_on() {
current->softirqs_enabled = 1;
}
}
preempt_count_sub(cnt) {
trace_preempt_on() {
tracepoint() {
rcu_read_lock_sched() {
// jumps into lockdep
Where preempt_count still has softirqs disabled, but
current->softirqs_enabled is true, and we get a splat.
Cc: stable at vger.kernel.org
Reviewed-by: Steven Rostedt (VMware) <rostedt at goodmis.org>
Fixes: d59158162e032 ("tracing: Add support for preempt and irq enable/disable events")
Signed-off-by: Joel Fernandes (Google) <joel at joelfernandes.org>
---
kernel/softirq.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 177de3640c78..8a040bcaa033 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt)
{
lockdep_assert_irqs_disabled();
+ if (preempt_count() == cnt)
+ trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
+
if (softirq_count() == (cnt & SOFTIRQ_MASK))
trace_softirqs_on(_RET_IP_);
- preempt_count_sub(cnt);
+
+ __preempt_count_sub(cnt);
}
/*
--
2.17.0.441.gb46fe60e1d-goog
--
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WARNING: multiple messages have this Message-ID
From: joelaf@google.com (Joel Fernandes)
Subject: [PATCH v7 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat
Date: Wed, 23 May 2018 18:21:50 -0700 [thread overview]
Message-ID: <20180524012157.181277-2-joel@joelfernandes.org> (raw)
Message-ID: <20180524012150.kxXfF9t-XazJT1wbZyy_MXvqJEEIQKo7CiCdnxg3rzo@z> (raw)
In-Reply-To: <20180524012157.181277-1-joel@joelfernandes.org>
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
I'm able to reproduce a lockdep splat with config options:
CONFIG_PROVE_LOCKING=y,
CONFIG_DEBUG_LOCK_ALLOC=y and
CONFIG_PREEMPTIRQ_EVENTS=y
$ echo 1 > /d/tracing/events/preemptirq/preempt_enable/enable
[ 26.112609] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled)
[ 26.112636] WARNING: CPU: 0 PID: 118 at kernel/locking/lockdep.c:3854
[...]
[ 26.144229] Call Trace:
[ 26.144926] <IRQ>
[ 26.145506] lock_acquire+0x55/0x1b0
[ 26.146499] ? __do_softirq+0x46f/0x4d9
[ 26.147571] ? __do_softirq+0x46f/0x4d9
[ 26.148646] trace_preempt_on+0x8f/0x240
[ 26.149744] ? trace_preempt_on+0x4d/0x240
[ 26.150862] ? __do_softirq+0x46f/0x4d9
[ 26.151930] preempt_count_sub+0x18a/0x1a0
[ 26.152985] __do_softirq+0x46f/0x4d9
[ 26.153937] irq_exit+0x68/0xe0
[ 26.154755] smp_apic_timer_interrupt+0x271/0x280
[ 26.156056] apic_timer_interrupt+0xf/0x20
[ 26.157105] </IRQ>
The issue was this:
preempt_count = 1 << SOFTIRQ_SHIFT
__local_bh_enable(cnt = 1 << SOFTIRQ_SHIFT) {
if (softirq_count() == (cnt && SOFTIRQ_MASK)) {
trace_softirqs_on() {
current->softirqs_enabled = 1;
}
}
preempt_count_sub(cnt) {
trace_preempt_on() {
tracepoint() {
rcu_read_lock_sched() {
// jumps into lockdep
Where preempt_count still has softirqs disabled, but
current->softirqs_enabled is true, and we get a splat.
Cc: stable at vger.kernel.org
Reviewed-by: Steven Rostedt (VMware) <rostedt at goodmis.org>
Fixes: d59158162e032 ("tracing: Add support for preempt and irq enable/disable events")
Signed-off-by: Joel Fernandes (Google) <joel at joelfernandes.org>
---
kernel/softirq.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 177de3640c78..8a040bcaa033 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -139,9 +139,13 @@ static void __local_bh_enable(unsigned int cnt)
{
lockdep_assert_irqs_disabled();
+ if (preempt_count() == cnt)
+ trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
+
if (softirq_count() == (cnt & SOFTIRQ_MASK))
trace_softirqs_on(_RET_IP_);
- preempt_count_sub(cnt);
+
+ __preempt_count_sub(cnt);
}
/*
--
2.17.0.441.gb46fe60e1d-goog
--
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next prev parent reply other threads:[~2018-05-24 1:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-24 1:21 [PATCH v7 0/8] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` Joel Fernandes [this message]
2018-05-24 1:21 ` [PATCH v7 1/8] softirq: reorder trace_softirqs_on to prevent lockdep splat Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 2/8] srcu: Add notrace variants of srcu_read_{lock,unlock} Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 3/8] srcu: Add notrace variant of srcu_dereference Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 4/8] trace/irqsoff: Split reset into separate functions Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 5/8] tracepoint: Make rcuidle tracepoint callers use SRCU Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 6/8] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-25 11:43 ` Namhyung Kim
2018-05-25 11:43 ` Namhyung Kim
2018-05-25 11:43 ` namhyung
2018-05-25 23:20 ` Joel Fernandes
2018-05-25 23:20 ` Joel Fernandes
2018-05-25 23:20 ` joel
2018-05-24 1:21 ` [PATCH v7 7/8] lib: Add module to simulate atomic sections for testing preemptoff tracers Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
2018-05-24 1:21 ` [PATCH v7 8/8] kselftests: Add tests for the preemptoff and irqsoff tracers Joel Fernandes
2018-05-24 1:21 ` Joel Fernandes
2018-05-24 1:21 ` joelaf
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