* [PATCH RT 4.19] rcutorture: Fix oops when selecting non-default torture_type
@ 2019-03-22 3:21 Scott Wood
2019-03-22 9:22 ` Sebastian Andrzej Siewior
2019-03-22 14:50 ` Paul E. McKenney
0 siblings, 2 replies; 3+ messages in thread
From: Scott Wood @ 2019-03-22 3:21 UTC (permalink / raw)
To: Thomas Gleixner, Sebastian Andrzej Siewior
Cc: linux-rt-users, linux-kernel, Paul E. McKenney, Juri Lelli, Scott Wood
rcu_bh is disabled on PREEMPT_RT via a stub ops that has no name. Thus,
if a torture_type other than "rcu" is used, rcu_torture_init() will
pass NULL to strcmp() when iterating over torture_ops[], and oops.
Signed-off-by: Scott Wood <swood@redhat.com>
---
With this applied to 4.19.25-rt16 and specifying torture_type=sched,
similar rcutorture failures are seen as with 5.0.3-rt1 (in which standard
torture_cype=rcu no longer has .extendables=0 and thus stresses similar
paths).
kernel/rcu/rcutorture.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7d2a615601e7..408d03048911 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -479,6 +479,7 @@ static struct rcu_torture_ops rcu_bh_ops = {
#else
static struct rcu_torture_ops rcu_bh_ops = {
.ttype = INVALID_RCU_FLAVOR,
+ .name = "rcu_bh"
};
#endif
--
2.18.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH RT 4.19] rcutorture: Fix oops when selecting non-default torture_type
2019-03-22 3:21 [PATCH RT 4.19] rcutorture: Fix oops when selecting non-default torture_type Scott Wood
@ 2019-03-22 9:22 ` Sebastian Andrzej Siewior
2019-03-22 14:50 ` Paul E. McKenney
1 sibling, 0 replies; 3+ messages in thread
From: Sebastian Andrzej Siewior @ 2019-03-22 9:22 UTC (permalink / raw)
To: Scott Wood
Cc: Thomas Gleixner, linux-rt-users, linux-kernel, Paul E. McKenney,
Juri Lelli, anna-maria, Steven Rostedt
On 2019-03-21 22:21:21 [-0500], Scott Wood wrote:
> rcu_bh is disabled on PREEMPT_RT via a stub ops that has no name. Thus,
> if a torture_type other than "rcu" is used, rcu_torture_init() will
> pass NULL to strcmp() when iterating over torture_ops[], and oops.
>
> Signed-off-by: Scott Wood <swood@redhat.com>
> ---
> With this applied to 4.19.25-rt16 and specifying torture_type=sched,
> similar rcutorture failures are seen as with 5.0.3-rt1 (in which standard
> torture_cype=rcu no longer has .extendables=0 and thus stresses similar
> paths).
Anna-Maria was talking about this to me a long time ago, I though we
fixed that. But since your patch targets v4.19 it is not the case.
As far v4.19 goes, I think it can go in but this is up to Steven now.
Does this still apply to 5.0-RT? The RCU was greatly reworked so it may
no longer apply and just work. However the "random context" in
rcutorture gives me a headache right now…
> kernel/rcu/rcutorture.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 7d2a615601e7..408d03048911 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -479,6 +479,7 @@ static struct rcu_torture_ops rcu_bh_ops = {
> #else
> static struct rcu_torture_ops rcu_bh_ops = {
> .ttype = INVALID_RCU_FLAVOR,
> + .name = "rcu_bh"
> };
> #endif
>
Sebastian
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH RT 4.19] rcutorture: Fix oops when selecting non-default torture_type
2019-03-22 3:21 [PATCH RT 4.19] rcutorture: Fix oops when selecting non-default torture_type Scott Wood
2019-03-22 9:22 ` Sebastian Andrzej Siewior
@ 2019-03-22 14:50 ` Paul E. McKenney
1 sibling, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2019-03-22 14:50 UTC (permalink / raw)
To: Scott Wood
Cc: Thomas Gleixner, Sebastian Andrzej Siewior, linux-rt-users,
linux-kernel, Juri Lelli
On Thu, Mar 21, 2019 at 10:21:21PM -0500, Scott Wood wrote:
> rcu_bh is disabled on PREEMPT_RT via a stub ops that has no name. Thus,
> if a torture_type other than "rcu" is used, rcu_torture_init() will
> pass NULL to strcmp() when iterating over torture_ops[], and oops.
>
> Signed-off-by: Scott Wood <swood@redhat.com>
This rcu_bh torture type is gone completely in mainline, however,
I just yesterday queued a patch to fix some problems when an invalid
torture_type was specified.
Mainline 4.19 does have the .name element of rcu_bh_ops specified,
though. Not sure what happened here, but you are absolutely
correct that rcu_bh_ops does need a .name initializer.
Thanx, Paul
> ---
> With this applied to 4.19.25-rt16 and specifying torture_type=sched,
> similar rcutorture failures are seen as with 5.0.3-rt1 (in which standard
> torture_cype=rcu no longer has .extendables=0 and thus stresses similar
> paths).
>
> kernel/rcu/rcutorture.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> index 7d2a615601e7..408d03048911 100644
> --- a/kernel/rcu/rcutorture.c
> +++ b/kernel/rcu/rcutorture.c
> @@ -479,6 +479,7 @@ static struct rcu_torture_ops rcu_bh_ops = {
> #else
> static struct rcu_torture_ops rcu_bh_ops = {
> .ttype = INVALID_RCU_FLAVOR,
> + .name = "rcu_bh"
> };
> #endif
>
> --
> 2.18.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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