* [BUG -tip/sched] INFO: suspicious RCU usage
@ 2011-12-07 7:39 Yong Zhang
2011-12-07 13:28 ` Peter Zijlstra
0 siblings, 1 reply; 5+ messages in thread
From: Yong Zhang @ 2011-12-07 7:39 UTC (permalink / raw)
To: linux-kernel; +Cc: a.p.zijlstra, mingo, Suresh Siddha
===============================
[ INFO: suspicious RCU usage. ]
-------------------------------
/build/linux/kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
1 lock held by swapper/0/1:
#0: (&sb->s_type->i_mutex_key#2){+.+.+.}, at: [<ffffffff812a0e0c>] debugfs_create_file+0x8c/0x270
stack backtrace:
Pid: 1, comm: swapper/0 Not tainted 3.2.0-rc1-00339-gcd490c5 #14
Call Trace:
<IRQ> [<ffffffff815f9968>] ? _raw_spin_unlock_irqrestore+0x38/0x80
[<ffffffff8109407f>] lockdep_rcu_suspicious+0xbf/0xe0
[<ffffffff8107dd48>] trigger_load_balance+0x5b8/0x5c0
[<ffffffff81070544>] scheduler_tick+0x104/0x160
[<ffffffff8104a1ce>] update_process_times+0x6e/0x90
[<ffffffff8108e32c>] tick_periodic+0x2c/0x70
[<ffffffff8108e394>] tick_handle_periodic+0x24/0x80
[<ffffffff812a07a7>] ? T.562+0xf7/0x170
[<ffffffff815fce56>] smp_apic_timer_interrupt+0x66/0x98
[<ffffffff815fb2f0>] apic_timer_interrupt+0x70/0x80
<EOI> [<ffffffff810984a4>] ? lock_release+0xe4/0x2b0
[<ffffffff815f98f3>] _raw_spin_unlock+0x23/0x60
[<ffffffff812a07a7>] T.562+0xf7/0x170
[<ffffffff812a0e71>] debugfs_create_file+0xf1/0x270
[<ffffffff810e96c9>] trace_create_file+0x19/0x50
[<ffffffff81af7b3c>] tracer_init_debugfs+0x2bd/0x3c0
[<ffffffff810e96c9>] ? trace_create_file+0x19/0x50
[<ffffffff81af787f>] ? clear_boot_tracer+0x2d/0x2d
[<ffffffff810001d3>] do_one_initcall+0x43/0x180
[<ffffffff81adf637>] kernel_init+0xd0/0x156
[<ffffffff815fc574>] kernel_thread_helper+0x4/0x10
[<ffffffff8106fdb8>] ? finish_task_switch+0x88/0xf0
[<ffffffff815f99eb>] ? _raw_spin_unlock_irq+0x3b/0x70
[<ffffffff815f9f61>] ? retint_restore_args+0xe/0xe
[<ffffffff81adf567>] ? parse_early_options+0x20/0x20
[<ffffffff815fc570>] ? gs_change+0xb/0xb
Seems due to commit [0b005cf5: sched, nohz: Implement sched group, domain
aware nohz idle load balancing]
Thanks,
Yong
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [BUG -tip/sched] INFO: suspicious RCU usage
2011-12-07 7:39 [BUG -tip/sched] INFO: suspicious RCU usage Yong Zhang
@ 2011-12-07 13:28 ` Peter Zijlstra
2011-12-07 13:32 ` Peter Zijlstra
0 siblings, 1 reply; 5+ messages in thread
From: Peter Zijlstra @ 2011-12-07 13:28 UTC (permalink / raw)
To: Yong Zhang; +Cc: linux-kernel, mingo, Suresh Siddha
On Wed, 2011-12-07 at 15:39 +0800, Yong Zhang wrote:
> ===============================
> [ INFO: suspicious RCU usage. ]
> -------------------------------
> /build/linux/kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 1, debug_locks = 1
> 1 lock held by swapper/0/1:
> #0: (&sb->s_type->i_mutex_key#2){+.+.+.}, at: [<ffffffff812a0e0c>] debugfs_create_file+0x8c/0x270
>
> stack backtrace:
> Pid: 1, comm: swapper/0 Not tainted 3.2.0-rc1-00339-gcd490c5 #14
> Call Trace:
> <IRQ> [<ffffffff815f9968>] ? _raw_spin_unlock_irqrestore+0x38/0x80
> [<ffffffff8109407f>] lockdep_rcu_suspicious+0xbf/0xe0
> [<ffffffff8107dd48>] trigger_load_balance+0x5b8/0x5c0
> [<ffffffff81070544>] scheduler_tick+0x104/0x160
> [<ffffffff8104a1ce>] update_process_times+0x6e/0x90
> [<ffffffff8108e32c>] tick_periodic+0x2c/0x70
> [<ffffffff8108e394>] tick_handle_periodic+0x24/0x80
> [<ffffffff812a07a7>] ? T.562+0xf7/0x170
> [<ffffffff815fce56>] smp_apic_timer_interrupt+0x66/0x98
> [<ffffffff815fb2f0>] apic_timer_interrupt+0x70/0x80
> <EOI> [<ffffffff810984a4>] ? lock_release+0xe4/0x2b0
> [<ffffffff815f98f3>] _raw_spin_unlock+0x23/0x60
> [<ffffffff812a07a7>] T.562+0xf7/0x170
> [<ffffffff812a0e71>] debugfs_create_file+0xf1/0x270
> [<ffffffff810e96c9>] trace_create_file+0x19/0x50
> [<ffffffff81af7b3c>] tracer_init_debugfs+0x2bd/0x3c0
> [<ffffffff810e96c9>] ? trace_create_file+0x19/0x50
> [<ffffffff81af787f>] ? clear_boot_tracer+0x2d/0x2d
> [<ffffffff810001d3>] do_one_initcall+0x43/0x180
> [<ffffffff81adf637>] kernel_init+0xd0/0x156
> [<ffffffff815fc574>] kernel_thread_helper+0x4/0x10
> [<ffffffff8106fdb8>] ? finish_task_switch+0x88/0xf0
> [<ffffffff815f99eb>] ? _raw_spin_unlock_irq+0x3b/0x70
> [<ffffffff815f9f61>] ? retint_restore_args+0xe/0xe
> [<ffffffff81adf567>] ? parse_early_options+0x20/0x20
> [<ffffffff815fc570>] ? gs_change+0xb/0xb
>
> Seems due to commit [0b005cf5: sched, nohz: Implement sched group, domain
> aware nohz idle load balancing]
I think something like the below should suffice, the sd argument only
lives inside the for_each_domain() so wrapping the whole block should
suffice.
---
kernel/sched/fair.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6482136..a4d2b7a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
if (rq->nr_running >= 2)
goto need_kick;
+ rcu_read_lock();
for_each_domain(cpu, sd) {
struct sched_group *sg = sd->groups;
struct sched_group_power *sgp = sg->sgp;
int nr_busy = atomic_read(&sgp->nr_busy_cpus);
if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
- goto need_kick;
+ goto need_kick_unlock;
if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
&& (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
- goto need_kick;
+ goto need_kick_unlock;
if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
break;
}
+ rcu_read_unlock();
return 0;
+
+need_kick_unlock:
+ rcu_read_unlock();
need_kick:
return 1;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [BUG -tip/sched] INFO: suspicious RCU usage
2011-12-07 13:28 ` Peter Zijlstra
@ 2011-12-07 13:32 ` Peter Zijlstra
2011-12-08 1:55 ` Yong Zhang
2011-12-08 15:16 ` [tip:sched/core] sched, nohz: Fix missing RCU read lock tip-bot for Peter Zijlstra
0 siblings, 2 replies; 5+ messages in thread
From: Peter Zijlstra @ 2011-12-07 13:32 UTC (permalink / raw)
To: Yong Zhang; +Cc: linux-kernel, mingo, Suresh Siddha
I made that
---
Subject: sched, nohz: Fix missing RCU read lock
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed Dec 07 14:28:44 CET 2011
Yong Zhang reported:
> [ INFO: suspicious RCU usage. ]
> kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage!
This is due to the sched_domain stuff being RCU protected and commit
0b005cf5 ("sched, nohz: Implement sched group, domain
aware nohz idle load balancing") overlooking this fact.
The sd variable only lives inside the for_each_domain() block, so we
only need to wrap that.
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Reported-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-gt616u9aetdzgb1oc4m6uydr@git.kernel.org
---
Index: linux-2.6/kernel/sched/fair.c
===================================================================
--- linux-2.6.orig/kernel/sched/fair.c
+++ linux-2.6/kernel/sched/fair.c
@@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struc
if (rq->nr_running >= 2)
goto need_kick;
+ rcu_read_lock();
for_each_domain(cpu, sd) {
struct sched_group *sg = sd->groups;
struct sched_group_power *sgp = sg->sgp;
int nr_busy = atomic_read(&sgp->nr_busy_cpus);
if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
- goto need_kick;
+ goto need_kick_unlock;
if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
&& (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
- goto need_kick;
+ goto need_kick_unlock;
if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
break;
}
+ rcu_read_unlock();
return 0;
+
+need_kick_unlock:
+ rcu_read_unlock();
need_kick:
return 1;
}
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [BUG -tip/sched] INFO: suspicious RCU usage
2011-12-07 13:32 ` Peter Zijlstra
@ 2011-12-08 1:55 ` Yong Zhang
2011-12-08 15:16 ` [tip:sched/core] sched, nohz: Fix missing RCU read lock tip-bot for Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: Yong Zhang @ 2011-12-08 1:55 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: linux-kernel, mingo, Suresh Siddha
On Wed, Dec 07, 2011 at 02:32:08PM +0100, Peter Zijlstra wrote:
> I made that
>
> ---
> Subject: sched, nohz: Fix missing RCU read lock
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Wed Dec 07 14:28:44 CET 2011
>
> Yong Zhang reported:
>
> > [ INFO: suspicious RCU usage. ]
> > kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage!
>
> This is due to the sched_domain stuff being RCU protected and commit
> 0b005cf5 ("sched, nohz: Implement sched group, domain
> aware nohz idle load balancing") overlooking this fact.
>
> The sd variable only lives inside the for_each_domain() block, so we
> only need to wrap that.
>
Works for me.
Tested-by: Yong Zhang <yong.zhang0@gmail.com>
Thanks,
Yong
> Cc: Suresh Siddha <suresh.b.siddha@intel.com>
> Reported-by: Yong Zhang <yong.zhang0@gmail.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Link: http://lkml.kernel.org/n/tip-gt616u9aetdzgb1oc4m6uydr@git.kernel.org
> ---
> Index: linux-2.6/kernel/sched/fair.c
> ===================================================================
> --- linux-2.6.orig/kernel/sched/fair.c
> +++ linux-2.6/kernel/sched/fair.c
> @@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struc
> if (rq->nr_running >= 2)
> goto need_kick;
>
> + rcu_read_lock();
> for_each_domain(cpu, sd) {
> struct sched_group *sg = sd->groups;
> struct sched_group_power *sgp = sg->sgp;
> int nr_busy = atomic_read(&sgp->nr_busy_cpus);
>
> if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
> - goto need_kick;
> + goto need_kick_unlock;
>
> if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
> && (cpumask_first_and(nohz.idle_cpus_mask,
> sched_domain_span(sd)) < cpu))
> - goto need_kick;
> + goto need_kick_unlock;
>
> if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
> break;
> }
> + rcu_read_unlock();
> return 0;
> +
> +need_kick_unlock:
> + rcu_read_unlock();
> need_kick:
> return 1;
> }
>
> --
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^ permalink raw reply [flat|nested] 5+ messages in thread* [tip:sched/core] sched, nohz: Fix missing RCU read lock
2011-12-07 13:32 ` Peter Zijlstra
2011-12-08 1:55 ` Yong Zhang
@ 2011-12-08 15:16 ` tip-bot for Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: tip-bot for Peter Zijlstra @ 2011-12-08 15:16 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, a.p.zijlstra, peterz, suresh.b.siddha,
tglx, yong.zhang0, mingo
Commit-ID: 067491b7313c41f49607fce782d29344d1472587
Gitweb: http://git.kernel.org/tip/067491b7313c41f49607fce782d29344d1472587
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 7 Dec 2011 14:32:08 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 8 Dec 2011 05:45:48 +0100
sched, nohz: Fix missing RCU read lock
Yong Zhang reported:
> [ INFO: suspicious RCU usage. ]
> kernel/sched/fair.c:5091 suspicious rcu_dereference_check() usage!
This is due to the sched_domain stuff being RCU protected and
commit 0b005cf5 ("sched, nohz: Implement sched group, domain
aware nohz idle load balancing") overlooking this fact.
The sd variable only lives inside the for_each_domain() block,
so we only need to wrap that.
Reported-by: Yong Zhang <yong.zhang0@gmail.com>
Tested-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1323264728.32012.107.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched/fair.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6482136..a4d2b7a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5088,23 +5088,28 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
if (rq->nr_running >= 2)
goto need_kick;
+ rcu_read_lock();
for_each_domain(cpu, sd) {
struct sched_group *sg = sd->groups;
struct sched_group_power *sgp = sg->sgp;
int nr_busy = atomic_read(&sgp->nr_busy_cpus);
if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
- goto need_kick;
+ goto need_kick_unlock;
if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
&& (cpumask_first_and(nohz.idle_cpus_mask,
sched_domain_span(sd)) < cpu))
- goto need_kick;
+ goto need_kick_unlock;
if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
break;
}
+ rcu_read_unlock();
return 0;
+
+need_kick_unlock:
+ rcu_read_unlock();
need_kick:
return 1;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-12-08 15:17 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-12-07 7:39 [BUG -tip/sched] INFO: suspicious RCU usage Yong Zhang
2011-12-07 13:28 ` Peter Zijlstra
2011-12-07 13:32 ` Peter Zijlstra
2011-12-08 1:55 ` Yong Zhang
2011-12-08 15:16 ` [tip:sched/core] sched, nohz: Fix missing RCU read lock tip-bot for Peter Zijlstra
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