* [PATCH] sched/core: don't include asm/mmu_context from drivers
@ 2016-04-29 8:52 Arnd Bergmann
2016-04-29 13:42 ` Steven Rostedt
0 siblings, 1 reply; 7+ messages in thread
From: Arnd Bergmann @ 2016-04-29 8:52 UTC (permalink / raw)
To: Russell King, Ingo Molnar, Peter Zijlstra, Andy Lutomirski
Cc: Arnd Bergmann, Borislav Petkov, Ard Biesheuvel, Thomas Gleixner,
Frederic Weisbecker, Steven Rostedt, Mel Gorman,
linux-arm-kernel, linux-kernel
The introduction of switch_mm_irqs_off() brought back an old bug
regarding the use of preempt_enable_no_resched:
As part of 62b94a08da1b ("sched/preempt: Take away
preempt_enable_no_resched() from modules"), the definition of
preempt_enable_no_resched() is only available in built-in code,
not in loadable modules, so we can't generally use it from header
files. However, the ARM version of finish_arch_post_lock_switch()
calls preempt_enable_no_resched() and is defined as a static
inline function in asm/mmu_context.h. This in turn means we cannot
include asm/mmu_context.h from modules.
With today's tip tree, asm/mmu_context.h gets included from
linux/mmu_context.h, which is normally the exact pattern one would
expect, but unfortunately, linux/mmu_context.h can be included from
the vhost driver that is a loadable module, now causing this compile
time error:
In file included from ../include/linux/mmu_context.h:4:0,
from ../drivers/vhost/vhost.c:18:
../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch':
../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration]
preempt_enable_no_resched();
Andy already tried to fix the bug by including linux/preempt.h
from asm/mmu_context.h, but that obviously didn't help.
This reverts the earlier fix attempt and works around the problem
by including both linux/mmu_context.h and asm/mmu_context.h from
kernel/sched/core.c. This is not a good solution but seems less
hacky than the alternatives.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
Reverts: 88f10e37e150 ("sched/core, ARM: Include linux/preempt.h from asm/mmu_context.h")
---
arch/arm/include/asm/mmu_context.h | 1 -
include/linux/mmu_context.h | 2 --
kernel/sched/core.c | 1 +
3 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index ed73babc0dc9..fa5b42d44985 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -15,7 +15,6 @@
#include <linux/compiler.h>
#include <linux/sched.h>
-#include <linux/preempt.h>
#include <asm/cacheflush.h>
#include <asm/cachetype.h>
#include <asm/proc-fns.h>
diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h
index a4441784503b..88d270706792 100644
--- a/include/linux/mmu_context.h
+++ b/include/linux/mmu_context.h
@@ -1,8 +1,6 @@
#ifndef _LINUX_MMU_CONTEXT_H
#define _LINUX_MMU_CONTEXT_H
-#include <asm/mmu_context.h>
-
struct mm_struct;
void use_mm(struct mm_struct *mm);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c82ca6eccfec..baa2a5152658 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -78,6 +78,7 @@
#include <asm/switch_to.h>
#include <asm/tlb.h>
#include <asm/irq_regs.h>
+#include <asm/mmu_context.h>
#include <asm/mutex.h>
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
--
2.7.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-04-29 8:52 [PATCH] sched/core: don't include asm/mmu_context from drivers Arnd Bergmann
@ 2016-04-29 13:42 ` Steven Rostedt
2016-04-29 15:37 ` Arnd Bergmann
2016-05-13 5:46 ` Andy Lutomirski
0 siblings, 2 replies; 7+ messages in thread
From: Steven Rostedt @ 2016-04-29 13:42 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Russell King, Ingo Molnar, Peter Zijlstra, Andy Lutomirski,
Borislav Petkov, Ard Biesheuvel, Thomas Gleixner,
Frederic Weisbecker, Mel Gorman, linux-arm-kernel, linux-kernel
On Fri, 29 Apr 2016 10:52:32 +0200
Arnd Bergmann <arnd@arndb.de> wrote:
> This reverts the earlier fix attempt and works around the problem
> by including both linux/mmu_context.h and asm/mmu_context.h from
> kernel/sched/core.c. This is not a good solution but seems less
> hacky than the alternatives.
What about simply not compiling finish_arch_post_lock_switch() when
building modules?
(untested, not compiled or anything)
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index fa5b42d44985..3f22d1b6bac8 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -66,6 +66,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
cpu_switch_mm(mm->pgd, mm);
}
+#ifndef MODULE
#define finish_arch_post_lock_switch \
finish_arch_post_lock_switch
static inline void finish_arch_post_lock_switch(void)
@@ -87,6 +88,7 @@ static inline void finish_arch_post_lock_switch(void)
preempt_enable_no_resched();
}
}
+#endif /* !MODULE */
#endif /* CONFIG_MMU */
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-04-29 13:42 ` Steven Rostedt
@ 2016-04-29 15:37 ` Arnd Bergmann
2016-04-29 18:52 ` Andy Lutomirski
2016-05-13 5:46 ` Andy Lutomirski
1 sibling, 1 reply; 7+ messages in thread
From: Arnd Bergmann @ 2016-04-29 15:37 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Steven Rostedt, Russell King, Ard Biesheuvel, Peter Zijlstra,
Frederic Weisbecker, linux-kernel, Ingo Molnar, Andy Lutomirski,
Thomas Gleixner, Borislav Petkov, Mel Gorman
On Friday 29 April 2016 09:42:18 Steven Rostedt wrote:
> On Fri, 29 Apr 2016 10:52:32 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
>
> > This reverts the earlier fix attempt and works around the problem
> > by including both linux/mmu_context.h and asm/mmu_context.h from
> > kernel/sched/core.c. This is not a good solution but seems less
> > hacky than the alternatives.
>
> What about simply not compiling finish_arch_post_lock_switch() when
> building modules?
>
> (untested, not compiled or anything)
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>
It should work as well.
I think I suggested doing that the last time the problem came up
a few years ago, but we ended up not including the header instead,
so I kept doing that.
Arnd
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-04-29 15:37 ` Arnd Bergmann
@ 2016-04-29 18:52 ` Andy Lutomirski
0 siblings, 0 replies; 7+ messages in thread
From: Andy Lutomirski @ 2016-04-29 18:52 UTC (permalink / raw)
To: Arnd Bergmann
Cc: linux-arm-kernel, Steven Rostedt, Russell King, Ard Biesheuvel,
Peter Zijlstra, Frederic Weisbecker, linux-kernel, Ingo Molnar,
Andy Lutomirski, Thomas Gleixner, Borislav Petkov, Mel Gorman
On Fri, Apr 29, 2016 at 8:37 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Friday 29 April 2016 09:42:18 Steven Rostedt wrote:
>> On Fri, 29 Apr 2016 10:52:32 +0200
>> Arnd Bergmann <arnd@arndb.de> wrote:
>>
>> > This reverts the earlier fix attempt and works around the problem
>> > by including both linux/mmu_context.h and asm/mmu_context.h from
>> > kernel/sched/core.c. This is not a good solution but seems less
>> > hacky than the alternatives.
>>
>> What about simply not compiling finish_arch_post_lock_switch() when
>> building modules?
>>
>> (untested, not compiled or anything)
>>
>> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>>
>
> It should work as well.
>
> I think I suggested doing that the last time the problem came up
> a few years ago, but we ended up not including the header instead,
> so I kept doing that.
>
> Arnd
This variant looks considerably nicer to me.
--Andy
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-04-29 13:42 ` Steven Rostedt
2016-04-29 15:37 ` Arnd Bergmann
@ 2016-05-13 5:46 ` Andy Lutomirski
2016-05-13 9:15 ` Russell King - ARM Linux
2016-05-13 9:28 ` Arnd Bergmann
1 sibling, 2 replies; 7+ messages in thread
From: Andy Lutomirski @ 2016-05-13 5:46 UTC (permalink / raw)
To: Steven Rostedt, Guenter Roeck
Cc: Arnd Bergmann, Russell King, Ingo Molnar, Peter Zijlstra,
Andy Lutomirski, Borislav Petkov, Ard Biesheuvel,
Thomas Gleixner, Frederic Weisbecker, Mel Gorman,
linux-arm-kernel, linux-kernel
On Fri, Apr 29, 2016 at 6:42 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Fri, 29 Apr 2016 10:52:32 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
>
>> This reverts the earlier fix attempt and works around the problem
>> by including both linux/mmu_context.h and asm/mmu_context.h from
>> kernel/sched/core.c. This is not a good solution but seems less
>> hacky than the alternatives.
>
> What about simply not compiling finish_arch_post_lock_switch() when
> building modules?
>
> (untested, not compiled or anything)
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> index fa5b42d44985..3f22d1b6bac8 100644
> --- a/arch/arm/include/asm/mmu_context.h
> +++ b/arch/arm/include/asm/mmu_context.h
> @@ -66,6 +66,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
> cpu_switch_mm(mm->pgd, mm);
> }
>
> +#ifndef MODULE
> #define finish_arch_post_lock_switch \
> finish_arch_post_lock_switch
> static inline void finish_arch_post_lock_switch(void)
> @@ -87,6 +88,7 @@ static inline void finish_arch_post_lock_switch(void)
> preempt_enable_no_resched();
> }
> }
> +#endif /* !MODULE */
>
> #endif /* CONFIG_MMU */
>
Can someone in arm land ack this so Ingo can apply it?
--Andy
--
Andy Lutomirski
AMA Capital Management, LLC
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-05-13 5:46 ` Andy Lutomirski
@ 2016-05-13 9:15 ` Russell King - ARM Linux
2016-05-13 9:28 ` Arnd Bergmann
1 sibling, 0 replies; 7+ messages in thread
From: Russell King - ARM Linux @ 2016-05-13 9:15 UTC (permalink / raw)
To: Andy Lutomirski
Cc: Steven Rostedt, Guenter Roeck, Arnd Bergmann, Ingo Molnar,
Peter Zijlstra, Andy Lutomirski, Borislav Petkov, Ard Biesheuvel,
Thomas Gleixner, Frederic Weisbecker, Mel Gorman,
linux-arm-kernel, linux-kernel
On Thu, May 12, 2016 at 10:46:56PM -0700, Andy Lutomirski wrote:
> On Fri, Apr 29, 2016 at 6:42 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Fri, 29 Apr 2016 10:52:32 +0200
> > Arnd Bergmann <arnd@arndb.de> wrote:
> >
> >> This reverts the earlier fix attempt and works around the problem
> >> by including both linux/mmu_context.h and asm/mmu_context.h from
> >> kernel/sched/core.c. This is not a good solution but seems less
> >> hacky than the alternatives.
> >
> > What about simply not compiling finish_arch_post_lock_switch() when
> > building modules?
> >
> > (untested, not compiled or anything)
> >
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> > diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> > index fa5b42d44985..3f22d1b6bac8 100644
> > --- a/arch/arm/include/asm/mmu_context.h
> > +++ b/arch/arm/include/asm/mmu_context.h
> > @@ -66,6 +66,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
> > cpu_switch_mm(mm->pgd, mm);
> > }
> >
> > +#ifndef MODULE
> > #define finish_arch_post_lock_switch \
> > finish_arch_post_lock_switch
> > static inline void finish_arch_post_lock_switch(void)
> > @@ -87,6 +88,7 @@ static inline void finish_arch_post_lock_switch(void)
> > preempt_enable_no_resched();
> > }
> > }
> > +#endif /* !MODULE */
> >
> > #endif /* CONFIG_MMU */
> >
>
>
> Can someone in arm land ack this so Ingo can apply it?
Sorry, I'm simply unable to read every message that comes in.
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/core: don't include asm/mmu_context from drivers
2016-05-13 5:46 ` Andy Lutomirski
2016-05-13 9:15 ` Russell King - ARM Linux
@ 2016-05-13 9:28 ` Arnd Bergmann
1 sibling, 0 replies; 7+ messages in thread
From: Arnd Bergmann @ 2016-05-13 9:28 UTC (permalink / raw)
To: Andy Lutomirski
Cc: Steven Rostedt, Guenter Roeck, Russell King, Ingo Molnar,
Peter Zijlstra, Andy Lutomirski, Borislav Petkov, Ard Biesheuvel,
Thomas Gleixner, Frederic Weisbecker, Mel Gorman,
linux-arm-kernel, linux-kernel
On Thursday 12 May 2016 22:46:56 Andy Lutomirski wrote:
> On Fri, Apr 29, 2016 at 6:42 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Fri, 29 Apr 2016 10:52:32 +0200
> > Arnd Bergmann <arnd@arndb.de> wrote:
> >
> >> This reverts the earlier fix attempt and works around the problem
> >> by including both linux/mmu_context.h and asm/mmu_context.h from
> >> kernel/sched/core.c. This is not a good solution but seems less
> >> hacky than the alternatives.
> >
> > What about simply not compiling finish_arch_post_lock_switch() when
> > building modules?
> >
> > (untested, not compiled or anything)
> >
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > ---
> > diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> > index fa5b42d44985..3f22d1b6bac8 100644
> > --- a/arch/arm/include/asm/mmu_context.h
> > +++ b/arch/arm/include/asm/mmu_context.h
> > @@ -66,6 +66,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
> > cpu_switch_mm(mm->pgd, mm);
> > }
> >
> > +#ifndef MODULE
> > #define finish_arch_post_lock_switch \
> > finish_arch_post_lock_switch
> > static inline void finish_arch_post_lock_switch(void)
> > @@ -87,6 +88,7 @@ static inline void finish_arch_post_lock_switch(void)
> > preempt_enable_no_resched();
> > }
> > }
> > +#endif /* !MODULE */
> >
> > #endif /* CONFIG_MMU */
> >
>
>
> Can someone in arm land ack this so Ingo can apply it?
>
Sorry I forgot about this when I had my original patch in the
randconfig patch stack. I've reverted this now and am testing
with Steve's version. If I see no other regressions, I'll resend
this with a proper changelog and Russell's Ack.
Arnd
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2016-05-13 9:30 UTC | newest]
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2016-04-29 8:52 [PATCH] sched/core: don't include asm/mmu_context from drivers Arnd Bergmann
2016-04-29 13:42 ` Steven Rostedt
2016-04-29 15:37 ` Arnd Bergmann
2016-04-29 18:52 ` Andy Lutomirski
2016-05-13 5:46 ` Andy Lutomirski
2016-05-13 9:15 ` Russell King - ARM Linux
2016-05-13 9:28 ` Arnd Bergmann
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