Re: [alsa-devel] ❌ FAIL: Test report for kernel 5.3.9-rc1-dfe283e.cki (stable)

From: Jan Stancek <jstancek@redhat.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: alsa-devel@alsa-project.org, Memory Management <mm-qe@redhat.com>,
	Linux Stable maillist <stable@vger.kernel.org>,
	Jaroslav Kysela <jkysela@redhat.com>,
	CKI Project <cki-project@redhat.com>,
	LTP Mailing List <ltp@lists.linux.it>
Subject: Re: [alsa-devel] ❌ FAIL: Test report for kernel 5.3.9-rc1-dfe283e.cki (stable)
Date: Mon, 4 Nov 2019 09:28:10 -0500 (EST)	[thread overview]
Message-ID: <1341418315.10342806.1572877690830.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20191104135135.GA2162401@kroah.com>

----- Original Message -----
> On Mon, Nov 04, 2019 at 08:35:51AM -0500, Jan Stancek wrote:
> > 
> > 
> > ----- Original Message -----
> > > 
> > > Hello,
> > > 
> > > We ran automated tests on a recent commit from this kernel tree:
> > > 
> > >        Kernel repo:
> > >        git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
> > >             Commit: dfe283e9fdac - Linux 5.3.9-rc1
> > > 
> > > The results of these automated tests are provided below.
> > > 
> > >     Overall result: FAILED (see details below)
> > >              Merge: OK
> > >            Compile: OK
> > >              Tests: FAILED
> > > 
> > > All kernel binaries, config files, and logs are available for download
> > > here:
> > > 
> > >   https://artifacts.cki-project.org/pipelines/262380
> > > 
> > > One or more kernel tests failed:
> > > 
> > >     x86_64:
> > >      ❌ LTP lite
> > >
> > 
> > Not a 5.3 -stable regression.
> > 
> > Failure comes from test that sanity checks all /proc files by doing
> > 1k read from each. There are couple issues it hits wrt. snd_hda_*.
> > 
> > Example reproducer:
> >   dd if=/sys/kernel/debug/regmap/hdaudioC0D3-hdaudio/access of=out.txt
> >   count=1 bs=1024 iflag=nonblock
> 
> That's not a proc file :)

Right. It's same test that's used for /proc too.

> 
> > It's slow and triggers soft lockups [1]. And it also requires lot
> > of memory, triggering OOMs on smaller VMs:
> > 0x0000000024f0437b-0x000000001a32b1c8 1073745920 seq_read+0x131/0x400
> > pages=262144 vmalloc vpages N0=262144
> > 
> > I'm leaning towards skipping all regmap entries in this test.
> > Comments are welcomed.
> 
> Randomly poking around in debugfs is a sure way to cause crashes and
> major problems.  Also, debugfs files are NOT stable and only for
> debugging and should never be enabled on "real" systems.
> 
> So what exactly is the test trying to do here?

It's (unprivileged) user trying to open/read anything it can (/proc, /sys)
to see if that triggers anything bad.

It can run as privileged user too, which was the case above.

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/fs/read_all/read_all.c

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