From: Ira Weiny <ira.weiny@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Oliver Sang <oliver.sang@intel.com>,
Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
David Sterba <dsterba@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
"hch@infradead.org" <hch@infradead.org>,
Christoph Hellwig <hch@lst.de>,
LKML <linux-kernel@vger.kernel.org>,
"lkp@lists.01.org" <lkp@lists.01.org>,
"lkp@intel.com" <lkp@intel.com>,
Xing Zhengjun <zhengjun.xing@linux.intel.com>
Subject: Re: [mm/highmem] 61b205f579: WARNING:at_mm/highmem.c:#__kmap_local_sched_out
Date: Thu, 18 Mar 2021 16:08:39 -0700 [thread overview]
Message-ID: <20210318230839.GY3014244@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <87blbhzygm.fsf@nanos.tec.linutronix.de>
On Wed, Mar 17, 2021 at 02:44:41PM +0100, Thomas Gleixner wrote:
> On Tue, Mar 16 2021 at 00:37, Ira Weiny wrote:
> >
> > I think I see the issue. I think this is an invalid configuration.
> >
> > 00:26:43 > grep DEBUG_KMAP config-5.11.0-rc7-00002-g61b205f57991
> > CONFIG_DEBUG_KMAP_LOCAL=y
> > CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y
> >
> > 00:26:48 > grep DEBUG_HIGHMEM config-5.11.0-rc7-00002-g61b205f57991
> > # CONFIG_DEBUG_HIGHMEM is not set
>
> No. It's valid so you can test that crap on 64bit.
>
> > DEBUG_KMAP_LOCAL causes guard pages to be added to the kmap_ctrl array. But
> > DEBUG_HIGHMEM is used in __kmap_local_sched_out() to check the guard pages.
> >
> > DEBUG_HIGHMEM is supposed to select DEBUG_KMAP_LOCAL... but apparently that
> > did not happen when this configuration was made.
> >
> > I still have not hit this condition in my testing. Could you ensure that
> > DEBUG_HIGMEM is set and rerun the test to see if I am correct?
>
> Why? The whole point of CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is to allow
> testing of this kmap_local/atomic stuff w/o HIGHMEM, e.g. on 64 bit.
Ok yea I was looking at this backwards.
>
> > Thomas wouldn't the following enable checks make more sense? Or perhaps be
> > more consistent with the processing of kmap_ctrl?
>
> Neither nor. It's simply required to make DEBUG_KMAP_LOCAL=y &&
> HIGHMEM=n case work.
>
> Please add:
> Fixes: 0e91a0c6984c ("mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP")
>
Patch sent.
Thanks for setting me straight,
Ira
prev parent reply other threads:[~2021-03-18 23:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 8:38 [mm/highmem] 61b205f579: WARNING:at_mm/highmem.c:#__kmap_local_sched_out kernel test robot
2021-03-09 20:53 ` Chaitanya Kulkarni
2021-03-11 16:02 ` Ira Weiny
2021-03-12 6:27 ` Oliver Sang
2021-03-16 7:37 ` Ira Weiny
2021-03-17 13:44 ` Thomas Gleixner
2021-03-18 23:08 ` Ira Weiny [this message]
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