linux-kernel - Re: [PATCH] ARC: [*defconfigs] Enable hung tasks detection

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Message-ID: <1469120676.32401.8.camel@synopsys.com>
Date:	Thu, 21 Jul 2016 17:04:36 +0000
From:	Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
To:	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	"linux-snps-arc@...ts.infradead.org" 
	<linux-snps-arc@...ts.infradead.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Vineet.Gupta1@...opsys.com" <Vineet.Gupta1@...opsys.com>,
	"Alexey.Brodkin@...opsys.com" <Alexey.Brodkin@...opsys.com>,
	"christian.ruppert@...tech.com" <christian.ruppert@...tech.com>,
	"noamca@...lanox.com" <noamca@...lanox.com>,
	"Vladislav.Zakharov@...opsys.com" <Vladislav.Zakharov@...opsys.com>
Subject: Re: [PATCH] ARC: [*defconfigs] Enable hung tasks detection

Hi,
Not every time. For example, last time I debug mmap3 LTP's test, which 
stuck in "D" state, I didn't recieve any messages until I enabled this
option. This happends on nsim 700.
On Thu, 2016-07-21 at 09:17 -0700, Vineet Gupta wrote:
> On 07/21/2016 07:52 AM, Eugeniy Paltsev wrote:
> > 
> > Enable the kernel to detect "hung tasks",
> > which are bugs that cause the task to be stuck in
> > uninterruptible "D" state indefinitiley.
> spellos above
> 
> > 
> > Note we're setting HUNG_TASK_TIMEOUT to 10 seconds instead of
> > default 120 to shorten time required for detection of hung task,
> > as it set in axs101, axs103 and axs103_smp boards defconfigs.
> In some of the actual hang scenarios (on FPGA boards atleast) I was
> debugging, the
> hung task seemed redundant actually as I was getting RCU stall msgs
> as well. Do
> you not see something similar.
> 
> 
> > 
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
> > 
> > Cc: Christian Ruppert <christian.ruppert@...tech.com>
> > Cc: Noam Camus <noamca@...lanox.com>
> > Cc: Vineet Gupta <vgupta@...opsys.com>
> > Cc: Alexey Brodkin <abrodkin@...opsys.com>
> > Cc: Zakharov Vlad  <vzakhar@...opsys.com>
> > ---
> >  arch/arc/configs/nps_defconfig             | 2 ++
> >  arch/arc/configs/nsim_700_defconfig        | 2 ++
> >  arch/arc/configs/nsim_hs_defconfig         | 2 ++
> >  arch/arc/configs/nsim_hs_smp_defconfig     | 2 ++
> >  arch/arc/configs/nsimosci_defconfig        | 2 ++
> >  arch/arc/configs/nsimosci_hs_defconfig     | 3 +++
> >  arch/arc/configs/nsimosci_hs_smp_defconfig | 3 +++
> >  arch/arc/configs/tb10x_defconfig           | 1 +
> >  8 files changed, 17 insertions(+)
> > 
> > diff --git a/arch/arc/configs/nps_defconfig
> > b/arch/arc/configs/nps_defconfig
> > index ede625c..39ccacd 100644
> > --- a/arch/arc/configs/nps_defconfig
> > +++ b/arch/arc/configs/nps_defconfig
> > @@ -81,4 +81,6 @@ CONFIG_DEBUG_INFO=y
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> >  CONFIG_MAGIC_SYSRQ=y
> >  CONFIG_DEBUG_MEMORY_INIT=y
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> >  CONFIG_ENABLE_DEFAULT_TRACERS=y
> > diff --git a/arch/arc/configs/nsim_700_defconfig
> > b/arch/arc/configs/nsim_700_defconfig
> > index 7314f53..78c3070 100644
> > --- a/arch/arc/configs/nsim_700_defconfig
> > +++ b/arch/arc/configs/nsim_700_defconfig
> > @@ -61,4 +61,6 @@ CONFIG_TMPFS=y
> >  CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> >  # CONFIG_DEBUG_PREEMPT is not set
> > diff --git a/arch/arc/configs/nsim_hs_defconfig
> > b/arch/arc/configs/nsim_hs_defconfig
> > index a99dc7a..c6a0a30 100644
> > --- a/arch/arc/configs/nsim_hs_defconfig
> > +++ b/arch/arc/configs/nsim_hs_defconfig
> > @@ -59,4 +59,6 @@ CONFIG_TMPFS=y
> >  CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> >  # CONFIG_DEBUG_PREEMPT is not set
> > diff --git a/arch/arc/configs/nsim_hs_smp_defconfig
> > b/arch/arc/configs/nsim_hs_smp_defconfig
> > index 59f221f..10c5e5e 100644
> > --- a/arch/arc/configs/nsim_hs_smp_defconfig
> > +++ b/arch/arc/configs/nsim_hs_smp_defconfig
> > @@ -58,3 +58,5 @@ CONFIG_TMPFS=y
> >  CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> > diff --git a/arch/arc/configs/nsimosci_defconfig
> > b/arch/arc/configs/nsimosci_defconfig
> > index 42bafa5..973ce41 100644
> > --- a/arch/arc/configs/nsimosci_defconfig
> > +++ b/arch/arc/configs/nsimosci_defconfig
> > @@ -71,3 +71,5 @@ CONFIG_TMPFS=y
> >  CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> > diff --git a/arch/arc/configs/nsimosci_hs_defconfig
> > b/arch/arc/configs/nsimosci_hs_defconfig
> > index 4bb60c1..c0b99d7 100644
> > --- a/arch/arc/configs/nsimosci_hs_defconfig
> > +++ b/arch/arc/configs/nsimosci_hs_defconfig
> > @@ -70,3 +70,6 @@ CONFIG_TMPFS=y
> >  CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> > +CONFIG_DEBUG_KERNEL=y
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> > diff --git a/arch/arc/configs/nsimosci_hs_smp_defconfig
> > b/arch/arc/configs/nsimosci_hs_smp_defconfig
> > index 7e88f4c..4012585 100644
> > --- a/arch/arc/configs/nsimosci_hs_smp_defconfig
> > +++ b/arch/arc/configs/nsimosci_hs_smp_defconfig
> > @@ -84,3 +84,6 @@ CONFIG_NFS_FS=y
> >  # CONFIG_ENABLE_WARN_DEPRECATED is not set
> >  # CONFIG_ENABLE_MUST_CHECK is not set
> >  CONFIG_FTRACE=y
> > +CONFIG_DEBUG_KERNEL=y
> > +CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> > diff --git a/arch/arc/configs/tb10x_defconfig
> > b/arch/arc/configs/tb10x_defconfig
> > index 4c51183..e8a96eb 100644
> > --- a/arch/arc/configs/tb10x_defconfig
> > +++ b/arch/arc/configs/tb10x_defconfig
> > @@ -104,6 +104,7 @@ CONFIG_MAGIC_SYSRQ=y
> >  CONFIG_DEBUG_MEMORY_INIT=y
> >  CONFIG_DEBUG_STACKOVERFLOW=y
> >  CONFIG_DETECT_HUNG_TASK=y
> > +CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
> >  CONFIG_SCHEDSTATS=y
> >  CONFIG_TIMER_STATS=y
> >  # CONFIG_CRYPTO_HW is not set
> >