Re: [PATCH] PM: Fix crash on graph trace through x86 suspend

Re: [PATCH] PM: Fix crash on graph trace through x86 suspend

[Rafael J. Wysocki]

On Thu, Mar 3, 2016 at 1:43 AM, Todd Brandt
<todd.e.brandt@linux.intel.com> wrote:
> On Thu, 2016-03-03 at 01:19 +0100, Rafael J. Wysocki wrote:
>> On Thu, Mar 3, 2016 at 1:05 AM, Todd Brandt
>> <todd.e.brandt@linux.intel.com> wrote:
>> > Pause/unpause graph tracing around do_suspend_lowlevel as it has
>> > inconsistent call/return info after it jumps to the wakeup vector.
>> > The graph trace buffer will otherwise become misaligned and
>> > may eventually crash and hang on suspend.
>> >
>> > To reproduce the issue and test the fix:
>> > Run a function_graph trace over suspend/resume and set the graph
>> > function to suspend_devices_and_enter. This consistently hangs the
>> > system without this fix.
>> >
>> > Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
>>
>> OK
>>
>> I guess we'll need that in -stable, right?
>
> Sure, it's pretty important. The new analyze_suspend features are going
> to rely pretty heavily on full graph trace of suspend (all we can do is
> standby and freeze now because of the bug). Thanks!

OK, applied, but let Steven and the x86 folks see it.

>>
>> > ---
>> >  arch/x86/kernel/acpi/sleep.c | 7 +++++++
>> >  1 file changed, 7 insertions(+)
>> >
>> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>> > index d1daead..311360e 100644
>> > --- a/arch/x86/kernel/acpi/sleep.c
>> > +++ b/arch/x86/kernel/acpi/sleep.c
>> > @@ -16,6 +16,7 @@
>> >  #include <asm/cacheflush.h>
>> >  #include <asm/realmode.h>
>> >
>> > +#include <linux/ftrace.h>
>> >  #include "../../realmode/rm/wakeup.h"
>> >  #include "sleep.h"
>> >
>> > @@ -107,7 +108,13 @@ int x86_acpi_suspend_lowlevel(void)
>> >         saved_magic = 0x123456789abcdef0L;
>> >  #endif /* CONFIG_64BIT */
>> >
>> > +       /*
>> > +        * Pause/unpause graph tracing around do_suspend_lowlevel as it has
>> > +        * inconsistent call/return info after it jumps to the wakeup vector
>> > +        */
>> > +       pause_graph_tracing();
>> >         do_suspend_lowlevel();
>> > +       unpause_graph_tracing();
>> >         return 0;
>> >  }
>> >
>> > --
>> > 2.1.4
>> >
>> > --


Thanks,
Rafael

Re: [PATCH] PM: Fix crash on graph trace through x86 suspend

[Rafael J. Wysocki]

Well, fix up the Steven's address.

On Thu, Mar 3, 2016 at 2:34 AM, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Thu, Mar 3, 2016 at 1:43 AM, Todd Brandt
> <todd.e.brandt@linux.intel.com> wrote:
>> On Thu, 2016-03-03 at 01:19 +0100, Rafael J. Wysocki wrote:
>>> On Thu, Mar 3, 2016 at 1:05 AM, Todd Brandt
>>> <todd.e.brandt@linux.intel.com> wrote:
>>> > Pause/unpause graph tracing around do_suspend_lowlevel as it has
>>> > inconsistent call/return info after it jumps to the wakeup vector.
>>> > The graph trace buffer will otherwise become misaligned and
>>> > may eventually crash and hang on suspend.
>>> >
>>> > To reproduce the issue and test the fix:
>>> > Run a function_graph trace over suspend/resume and set the graph
>>> > function to suspend_devices_and_enter. This consistently hangs the
>>> > system without this fix.
>>> >
>>> > Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
>>>
>>> OK
>>>
>>> I guess we'll need that in -stable, right?
>>
>> Sure, it's pretty important. The new analyze_suspend features are going
>> to rely pretty heavily on full graph trace of suspend (all we can do is
>> standby and freeze now because of the bug). Thanks!
>
> OK, applied, but let Steven and the x86 folks see it.
>
>>>
>>> > ---
>>> >  arch/x86/kernel/acpi/sleep.c | 7 +++++++
>>> >  1 file changed, 7 insertions(+)
>>> >
>>> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
>>> > index d1daead..311360e 100644
>>> > --- a/arch/x86/kernel/acpi/sleep.c
>>> > +++ b/arch/x86/kernel/acpi/sleep.c
>>> > @@ -16,6 +16,7 @@
>>> >  #include <asm/cacheflush.h>
>>> >  #include <asm/realmode.h>
>>> >
>>> > +#include <linux/ftrace.h>
>>> >  #include "../../realmode/rm/wakeup.h"
>>> >  #include "sleep.h"
>>> >
>>> > @@ -107,7 +108,13 @@ int x86_acpi_suspend_lowlevel(void)
>>> >         saved_magic = 0x123456789abcdef0L;
>>> >  #endif /* CONFIG_64BIT */
>>> >
>>> > +       /*
>>> > +        * Pause/unpause graph tracing around do_suspend_lowlevel as it has
>>> > +        * inconsistent call/return info after it jumps to the wakeup vector
>>> > +        */
>>> > +       pause_graph_tracing();
>>> >         do_suspend_lowlevel();
>>> > +       unpause_graph_tracing();
>>> >         return 0;
>>> >  }
>>> >
>>> > --
>>> > 2.1.4
>>> >
>>> > --
>
>
> Thanks,
> Rafael

Re: [PATCH] PM: Fix crash on graph trace through x86 suspend

[Steven Rostedt]

On Thu, 3 Mar 2016 02:36:26 +0100
"Rafael J. Wysocki" <rafael@kernel.org> wrote:

> > OK, applied, but let Steven and the x86 folks see it.

The below patch looks fine to me. Anything else I should look at?

-- Steve

> >  
> >>>  
> >>> > ---
> >>> >  arch/x86/kernel/acpi/sleep.c | 7 +++++++
> >>> >  1 file changed, 7 insertions(+)
> >>> >
> >>> > diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> >>> > index d1daead..311360e 100644
> >>> > --- a/arch/x86/kernel/acpi/sleep.c
> >>> > +++ b/arch/x86/kernel/acpi/sleep.c
> >>> > @@ -16,6 +16,7 @@
> >>> >  #include <asm/cacheflush.h>
> >>> >  #include <asm/realmode.h>
> >>> >
> >>> > +#include <linux/ftrace.h>
> >>> >  #include "../../realmode/rm/wakeup.h"
> >>> >  #include "sleep.h"
> >>> >
> >>> > @@ -107,7 +108,13 @@ int x86_acpi_suspend_lowlevel(void)
> >>> >         saved_magic = 0x123456789abcdef0L;
> >>> >  #endif /* CONFIG_64BIT */
> >>> >
> >>> > +       /*
> >>> > +        * Pause/unpause graph tracing around do_suspend_lowlevel as it has
> >>> > +        * inconsistent call/return info after it jumps to the wakeup vector
> >>> > +        */
> >>> > +       pause_graph_tracing();
> >>> >         do_suspend_lowlevel();
> >>> > +       unpause_graph_tracing();
> >>> >         return 0;
> >>> >  }
> >>> >
> >>> > --
> >>> > 2.1.4
> >>> >
> >>> > --  
> >
> >
> > Thanks,
> > Rafael  

Re: [PATCH] PM: Fix crash on graph trace through x86 suspend

[Rafael J. Wysocki]

On Thu, Mar 3, 2016 at 3:07 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 3 Mar 2016 02:36:26 +0100
> "Rafael J. Wysocki" <rafael@kernel.org> wrote:
>
>> > OK, applied, but let Steven and the x86 folks see it.
>
> The below patch looks fine to me. Anything else I should look at?

No, that was it, thanks!