FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[gregkh]

The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From f37755490fe9bf76f6ba1d8c6591745d3574a6a6 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Mon, 15 Feb 2016 12:36:14 -0500
Subject: [PATCH] tracepoints: Do not trace when cpu is offline

The tracepoint infrastructure uses RCU sched protection to enable and
disable tracepoints safely. There are some instances where tracepoints are
used in infrastructure code (like kfree()) that get called after a CPU is
going offline, and perhaps when it is coming back online but hasn't been
registered yet.

This can probuce the following warning:

 [ INFO: suspicious RCU usage. ]
 4.4.0-00006-g0fe53e8-dirty #34 Tainted: G S
 -------------------------------
 include/trace/events/kmem.h:141 suspicious rcu_dereference_check() usage!

 other info that might help us debug this:

 RCU used illegally from offline CPU!  rcu_scheduler_active = 1, debug_locks = 1
 no locks held by swapper/8/0.

 stack backtrace:
  CPU: 8 PID: 0 Comm: swapper/8 Tainted: G S              4.4.0-00006-g0fe53e8-dirty #34
  Call Trace:
  [c0000005b76c78d0] [c0000000008b9540] .dump_stack+0x98/0xd4 (unreliable)
  [c0000005b76c7950] [c00000000010c898] .lockdep_rcu_suspicious+0x108/0x170
  [c0000005b76c79e0] [c00000000029adc0] .kfree+0x390/0x440
  [c0000005b76c7a80] [c000000000055f74] .destroy_context+0x44/0x100
  [c0000005b76c7b00] [c0000000000934a0] .__mmdrop+0x60/0x150
  [c0000005b76c7b90] [c0000000000e3ff0] .idle_task_exit+0x130/0x140
  [c0000005b76c7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310
  [c0000005b76c7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60
  [c0000005b76c7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40
  [c0000005b76c7db0] [c000000000101e6c] .cpu_startup_entry+0x50c/0x560
  [c0000005b76c7ed0] [c000000000043bd8] .start_secondary+0x328/0x360
  [c0000005b76c7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14

This warning is not a false positive either. RCU is not protecting code that
is being executed while the CPU is offline.

Instead of playing "whack-a-mole(TM)" and adding conditional statements to
the tracepoints we find that are used in this instance, simply add a
cpu_online() test to the tracepoint code where the tracepoint will be
ignored if the CPU is offline.

Use of raw_smp_processor_id() is fine, as there should never be a case where
the tracepoint code goes from running on a CPU that is online and suddenly
gets migrated to a CPU that is offline.

Link: http://lkml.kernel.org/r/1455387773-4245-1-git-send-email-kda@linux-powerpc.org

Reported-by: Denis Kirjanov <kda@linux-powerpc.org>
Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index acd522a91539..acfdbf353a0b 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -14,8 +14,10 @@
  * See the file COPYING for more details.
  */
 
+#include <linux/smp.h>
 #include <linux/errno.h>
 #include <linux/types.h>
+#include <linux/cpumask.h>
 #include <linux/rcupdate.h>
 #include <linux/tracepoint-defs.h>
 
@@ -132,6 +134,9 @@ extern void syscall_unregfunc(void);
 		void *it_func;						\
 		void *__data;						\
 									\
+		if (!cpu_online(raw_smp_processor_id()))		\
+			return;						\
+									\
 		if (!(cond))						\
 			return;						\
 		prercu;							\

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Tue, 23 Feb 2016 16:48:47 -0800
<gregkh@linuxfoundation.org> wrote:

> The patch below does not apply to the 3.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Hmm, strange. I just checked out v3.14.60 and did:

 $ git cherry-pick f37755490fe9bf76f6ba1d8c6591745d3574a6a6

and it applied without issue.

Below is the result.

-- Steve

> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> >From f37755490fe9bf76f6ba1d8c6591745d3574a6a6 Mon Sep 17 00:00:00 2001  
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> Date: Mon, 15 Feb 2016 12:36:14 -0500
> Subject: [PATCH] tracepoints: Do not trace when cpu is offline
> 
>


>From 5921fea2b95c0795d88f7b82633242c341be2efc Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Mon, 15 Feb 2016 12:36:14 -0500
Subject: [PATCH] tracepoints: Do not trace when cpu is offline

The tracepoint infrastructure uses RCU sched protection to enable and
disable tracepoints safely. There are some instances where tracepoints are
used in infrastructure code (like kfree()) that get called after a CPU is
going offline, and perhaps when it is coming back online but hasn't been
registered yet.

This can probuce the following warning:

 [ INFO: suspicious RCU usage. ]
 4.4.0-00006-g0fe53e8-dirty #34 Tainted: G S
 -------------------------------
 include/trace/events/kmem.h:141 suspicious rcu_dereference_check() usage!

 other info that might help us debug this:

 RCU used illegally from offline CPU!  rcu_scheduler_active = 1, debug_locks = 1
 no locks held by swapper/8/0.

 stack backtrace:
  CPU: 8 PID: 0 Comm: swapper/8 Tainted: G S              4.4.0-00006-g0fe53e8-dirty #34
  Call Trace:
  [c0000005b76c78d0] [c0000000008b9540] .dump_stack+0x98/0xd4 (unreliable)
  [c0000005b76c7950] [c00000000010c898] .lockdep_rcu_suspicious+0x108/0x170
  [c0000005b76c79e0] [c00000000029adc0] .kfree+0x390/0x440
  [c0000005b76c7a80] [c000000000055f74] .destroy_context+0x44/0x100
  [c0000005b76c7b00] [c0000000000934a0] .__mmdrop+0x60/0x150
  [c0000005b76c7b90] [c0000000000e3ff0] .idle_task_exit+0x130/0x140
  [c0000005b76c7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310
  [c0000005b76c7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60
  [c0000005b76c7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40
  [c0000005b76c7db0] [c000000000101e6c] .cpu_startup_entry+0x50c/0x560
  [c0000005b76c7ed0] [c000000000043bd8] .start_secondary+0x328/0x360
  [c0000005b76c7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14

This warning is not a false positive either. RCU is not protecting code that
is being executed while the CPU is offline.

Instead of playing "whack-a-mole(TM)" and adding conditional statements to
the tracepoints we find that are used in this instance, simply add a
cpu_online() test to the tracepoint code where the tracepoint will be
ignored if the CPU is offline.

Use of raw_smp_processor_id() is fine, as there should never be a case where
the tracepoint code goes from running on a CPU that is online and suddenly
gets migrated to a CPU that is offline.

Link: http://lkml.kernel.org/r/1455387773-4245-1-git-send-email-kda@linux-powerpc.org

Reported-by: Denis Kirjanov <kda@linux-powerpc.org>
Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/tracepoint.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 7159a0a..8e344f6 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -14,8 +14,10 @@
  * See the file COPYING for more details.
  */
 
+#include <linux/smp.h>
 #include <linux/errno.h>
 #include <linux/types.h>
+#include <linux/cpumask.h>
 #include <linux/rcupdate.h>
 #include <linux/static_key.h>
 
@@ -126,6 +128,9 @@ static inline void tracepoint_synchronize_unregister(void)
 		void *it_func;						\
 		void *__data;						\
 									\
+		if (!cpu_online(raw_smp_processor_id()))		\
+			return;						\
+									\
 		if (!(cond))						\
 			return;						\
 		prercu;							\
-- 
2.7.0

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Greg KH]

On Tue, Feb 23, 2016 at 10:24:40PM -0500, Steven Rostedt wrote:
> On Tue, 23 Feb 2016 16:48:47 -0800
> <gregkh@linuxfoundation.org> wrote:
> 
> > The patch below does not apply to the 3.14-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> Hmm, strange. I just checked out v3.14.60 and did:
> 
>  $ git cherry-pick f37755490fe9bf76f6ba1d8c6591745d3574a6a6
> 
> and it applied without issue.

Yes, it applies, sorry, but it breaks the build :(

Same for 3.10-stable.  It applies but can not compile.

can you fix that up?

thanks,

greg k-h

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Tue, 23 Feb 2016 19:37:04 -0800
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Tue, Feb 23, 2016 at 10:24:40PM -0500, Steven Rostedt wrote:
> > On Tue, 23 Feb 2016 16:48:47 -0800
> > <gregkh@linuxfoundation.org> wrote:
> >   
> > > The patch below does not apply to the 3.14-stable tree.
> > > If someone wants it applied there, or to any other stable or longterm
> > > tree, then please email the backport, including the original git commit
> > > id to <stable@vger.kernel.org>.  
> > 
> > Hmm, strange. I just checked out v3.14.60 and did:
> > 
> >  $ git cherry-pick f37755490fe9bf76f6ba1d8c6591745d3574a6a6
> > 
> > and it applied without issue.  
> 
> Yes, it applies, sorry, but it breaks the build :(
> 
> Same for 3.10-stable.  It applies but can not compile.
> 
> can you fix that up?

Yep I'll go work on that. But can you change your scripts to say it
broke the build, and possibly give a config file with it. The current
email just says "The patch below does not apply to the 3.14-stable
tree."

Thanks!

-- Steve

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Tue, 23 Feb 2016 19:37:04 -0800
Greg KH <gregkh@linuxfoundation.org> wrote:


> Yes, it applies, sorry, but it breaks the build :(
> 
> Same for 3.10-stable.  It applies but can not compile.
> 
> can you fix that up?
> 

Bah. smp.h isn't enough for using raw_smp_processor_id(). One must also
include percpu.h. That was fixed in mainline, but not in stable. But not
a big deal. I'll included percpu.h in tracepoint.h as well.

Here's the update for 3.14, and I'm guessing it would work in 3.10 as
well. I'll try it out.

-- Steve

>From c3d795582c64396ac163ed409cb9578d3cf3dbc6 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Date: Mon, 15 Feb 2016 12:36:14 -0500
Subject: [PATCH] tracepoints: Do not trace when cpu is offline

The tracepoint infrastructure uses RCU sched protection to enable and
disable tracepoints safely. There are some instances where tracepoints are
used in infrastructure code (like kfree()) that get called after a CPU is
going offline, and perhaps when it is coming back online but hasn't been
registered yet.

This can probuce the following warning:

 [ INFO: suspicious RCU usage. ]
 4.4.0-00006-g0fe53e8-dirty #34 Tainted: G S
 -------------------------------
 include/trace/events/kmem.h:141 suspicious rcu_dereference_check() usage!

 other info that might help us debug this:

 RCU used illegally from offline CPU!  rcu_scheduler_active = 1, debug_locks = 1
 no locks held by swapper/8/0.

 stack backtrace:
  CPU: 8 PID: 0 Comm: swapper/8 Tainted: G S              4.4.0-00006-g0fe53e8-dirty #34
  Call Trace:
  [c0000005b76c78d0] [c0000000008b9540] .dump_stack+0x98/0xd4 (unreliable)
  [c0000005b76c7950] [c00000000010c898] .lockdep_rcu_suspicious+0x108/0x170
  [c0000005b76c79e0] [c00000000029adc0] .kfree+0x390/0x440
  [c0000005b76c7a80] [c000000000055f74] .destroy_context+0x44/0x100
  [c0000005b76c7b00] [c0000000000934a0] .__mmdrop+0x60/0x150
  [c0000005b76c7b90] [c0000000000e3ff0] .idle_task_exit+0x130/0x140
  [c0000005b76c7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310
  [c0000005b76c7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60
  [c0000005b76c7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40
  [c0000005b76c7db0] [c000000000101e6c] .cpu_startup_entry+0x50c/0x560
  [c0000005b76c7ed0] [c000000000043bd8] .start_secondary+0x328/0x360
  [c0000005b76c7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14

This warning is not a false positive either. RCU is not protecting code that
is being executed while the CPU is offline.

Instead of playing "whack-a-mole(TM)" and adding conditional statements to
the tracepoints we find that are used in this instance, simply add a
cpu_online() test to the tracepoint code where the tracepoint will be
ignored if the CPU is offline.

Use of raw_smp_processor_id() is fine, as there should never be a case where
the tracepoint code goes from running on a CPU that is online and suddenly
gets migrated to a CPU that is offline.

Link: http://lkml.kernel.org/r/1455387773-4245-1-git-send-email-kda@linux-powerpc.org

Reported-by: Denis Kirjanov <kda@linux-powerpc.org>
Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/tracepoint.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 7159a0a933df..97c8689c7e51 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -14,8 +14,11 @@
  * See the file COPYING for more details.
  */
 
+#include <linux/smp.h>
 #include <linux/errno.h>
 #include <linux/types.h>
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
 #include <linux/rcupdate.h>
 #include <linux/static_key.h>
 
@@ -126,6 +129,9 @@ static inline void tracepoint_synchronize_unregister(void)
 		void *it_func;						\
 		void *__data;						\
 									\
+		if (!cpu_online(raw_smp_processor_id()))		\
+			return;						\
+									\
 		if (!(cond))						\
 			return;						\
 		prercu;							\
-- 
1.8.3.1

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Wed, 24 Feb 2016 10:18:32 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Tue, 23 Feb 2016 19:37:04 -0800
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> 
> > Yes, it applies, sorry, but it breaks the build :(
> > 
> > Same for 3.10-stable.  It applies but can not compile.
> > 
> > can you fix that up?
> >   
> 
> Bah. smp.h isn't enough for using raw_smp_processor_id(). One must also
> include percpu.h. That was fixed in mainline, but not in stable. But not
> a big deal. I'll included percpu.h in tracepoint.h as well.
> 
> Here's the update for 3.14, and I'm guessing it would work in 3.10 as
> well. I'll try it out.

I tested this too on 3.10 (cherry picked it from my 3.14 branch). It
builds and boots fine.

-- Steve

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Greg KH]

On Wed, Feb 24, 2016 at 09:21:14AM -0500, Steven Rostedt wrote:
> On Tue, 23 Feb 2016 19:37:04 -0800
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Tue, Feb 23, 2016 at 10:24:40PM -0500, Steven Rostedt wrote:
> > > On Tue, 23 Feb 2016 16:48:47 -0800
> > > <gregkh@linuxfoundation.org> wrote:
> > >   
> > > > The patch below does not apply to the 3.14-stable tree.
> > > > If someone wants it applied there, or to any other stable or longterm
> > > > tree, then please email the backport, including the original git commit
> > > > id to <stable@vger.kernel.org>.  
> > > 
> > > Hmm, strange. I just checked out v3.14.60 and did:
> > > 
> > >  $ git cherry-pick f37755490fe9bf76f6ba1d8c6591745d3574a6a6
> > > 
> > > and it applied without issue.  
> > 
> > Yes, it applies, sorry, but it breaks the build :(
> > 
> > Same for 3.10-stable.  It applies but can not compile.
> > 
> > can you fix that up?
> 
> Yep I'll go work on that. But can you change your scripts to say it
> broke the build, and possibly give a config file with it. The current
> email just says "The patch below does not apply to the 3.14-stable
> tree."

The number of times that a patch applies but then breaks the build makes
it pretty low for me to write a new script for that, sorry...

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Greg KH]

On Wed, Feb 24, 2016 at 10:18:32AM -0500, Steven Rostedt wrote:
> On Tue, 23 Feb 2016 19:37:04 -0800
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> 
> > Yes, it applies, sorry, but it breaks the build :(
> > 
> > Same for 3.10-stable.  It applies but can not compile.
> > 
> > can you fix that up?
> > 
> 
> Bah. smp.h isn't enough for using raw_smp_processor_id(). One must also
> include percpu.h. That was fixed in mainline, but not in stable. But not
> a big deal. I'll included percpu.h in tracepoint.h as well.

What was the commit id that did that change?  Is it simple enough to
just take that patch instead?

> 
> Here's the update for 3.14, and I'm guessing it would work in 3.10 as
> well. I'll try it out.

Thanks, I'll queue these up for the next round of stable releases after
these.

greg k-h

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Wed, 24 Feb 2016 09:07:33 -0800
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Wed, Feb 24, 2016 at 09:21:14AM -0500, Steven Rostedt wrote:
> > On Tue, 23 Feb 2016 19:37:04 -0800
> > Greg KH <gregkh@linuxfoundation.org> wrote:
> >   
> > > On Tue, Feb 23, 2016 at 10:24:40PM -0500, Steven Rostedt wrote:  
> > > > On Tue, 23 Feb 2016 16:48:47 -0800
> > > > <gregkh@linuxfoundation.org> wrote:
> > > >     
> > > > > The patch below does not apply to the 3.14-stable tree.
> > > > > If someone wants it applied there, or to any other stable or longterm
> > > > > tree, then please email the backport, including the original git commit
> > > > > id to <stable@vger.kernel.org>.    
> > > > 
> > > > Hmm, strange. I just checked out v3.14.60 and did:
> > > > 
> > > >  $ git cherry-pick f37755490fe9bf76f6ba1d8c6591745d3574a6a6
> > > > 
> > > > and it applied without issue.    
> > > 
> > > Yes, it applies, sorry, but it breaks the build :(
> > > 
> > > Same for 3.10-stable.  It applies but can not compile.
> > > 
> > > can you fix that up?  
> > 
> > Yep I'll go work on that. But can you change your scripts to say it
> > broke the build, and possibly give a config file with it. The current
> > email just says "The patch below does not apply to the 3.14-stable
> > tree."  
> 
> The number of times that a patch applies but then breaks the build makes
> it pretty low for me to write a new script for that, sorry...

OK, then what about changing the wording to something like

"The patch below does not apply or breaks the build for 3.14-stable
tree"

?

It would prevent people like me from bothering you about saying "but it
does apply!"

-- Steve

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Steven Rostedt]

On Wed, 24 Feb 2016 09:14:18 -0800
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Wed, Feb 24, 2016 at 10:18:32AM -0500, Steven Rostedt wrote:
> > On Tue, 23 Feb 2016 19:37:04 -0800
> > Greg KH <gregkh@linuxfoundation.org> wrote:
> > 
> >   
> > > Yes, it applies, sorry, but it breaks the build :(
> > > 
> > > Same for 3.10-stable.  It applies but can not compile.
> > > 
> > > can you fix that up?
> > >   
> > 
> > Bah. smp.h isn't enough for using raw_smp_processor_id(). One must also
> > include percpu.h. That was fixed in mainline, but not in stable. But not
> > a big deal. I'll included percpu.h in tracepoint.h as well.  
> 
> What was the commit id that did that change?  Is it simple enough to
> just take that patch instead?
> 

Hmm, I don't know where the include is done. Perhaps something else
included it and it was just a luck that this commit works in mainline.

-- Steve

Re: FAILED: patch "[PATCH] tracepoints: Do not trace when cpu is offline" failed to apply to 3.14-stable tree

[Greg KH]

On Wed, Feb 24, 2016 at 12:50:33PM -0500, Steven Rostedt wrote:
> On Wed, 24 Feb 2016 09:14:18 -0800
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Wed, Feb 24, 2016 at 10:18:32AM -0500, Steven Rostedt wrote:
> > > On Tue, 23 Feb 2016 19:37:04 -0800
> > > Greg KH <gregkh@linuxfoundation.org> wrote:
> > > 
> > >   
> > > > Yes, it applies, sorry, but it breaks the build :(
> > > > 
> > > > Same for 3.10-stable.  It applies but can not compile.
> > > > 
> > > > can you fix that up?
> > > >   
> > > 
> > > Bah. smp.h isn't enough for using raw_smp_processor_id(). One must also
> > > include percpu.h. That was fixed in mainline, but not in stable. But not
> > > a big deal. I'll included percpu.h in tracepoint.h as well.  
> > 
> > What was the commit id that did that change?  Is it simple enough to
> > just take that patch instead?
> > 
> 
> Hmm, I don't know where the include is done. Perhaps something else
> included it and it was just a luck that this commit works in mainline.

Ok, I'll stick with what you sent, thanks.

greg k-h