Re: [PATCH] generic/233,270: unlimit the max locked memory size for io_uring

From: Eryu Guan <guan@eryu.me>
To: zlang@redhat.com
Cc: fstests@vger.kernel.org
Subject: Re: [PATCH] generic/233,270: unlimit the max locked memory size for io_uring
Date: Mon, 8 Feb 2021 00:23:36 +0800	[thread overview]
Message-ID: <20210207162336.GH2350@desktop> (raw)
In-Reply-To: <20210131163412.GZ14354@localhost.localdomain>

On Mon, Feb 01, 2021 at 12:34:13AM +0800, Zorro Lang wrote:
> On Sun, Jan 31, 2021 at 11:24:52PM +0800, Eryu Guan wrote:
> > On Thu, Jan 28, 2021 at 11:02:09AM +0800, Zorro Lang wrote:
> > > On Wed, Jan 27, 2021 at 03:43:40PM -0800, Darrick J. Wong wrote:
> > > > On Wed, Jan 27, 2021 at 03:21:43PM +0800, Zorro Lang wrote:
> > > > > The ltp/fsstress always fails on io_uring_queue_init() by returnning
> > > > > ENOMEM. Due to io_uring accounts memory it needs under the rlimit
> > > > > memlocked option, which can be quite low on some setups, especially
> > > > > on 64K pagesize machine. root isn't under this restriction, but
> > > > > regular users are. So only g/233 and g/270 which use $qa_user to run
> > > > > fsstress are failed.
> > > > > 
> > > > > To avoid this failure, set max locked memory to unlimited before doing
> > > > > fsstress, then restore it after test done.
> > > > > 
> > > > > Signed-off-by: Zorro Lang <zlang@redhat.com>
> > > > > ---
> > > > >  tests/generic/233 | 8 ++++++++
> > > > >  tests/generic/270 | 8 ++++++++
> > > > >  2 files changed, 16 insertions(+)
> > > > > 
> > > > > diff --git a/tests/generic/233 b/tests/generic/233
> > > > > index 7eda5774..342690c2 100755
> > > > > --- a/tests/generic/233
> > > > > +++ b/tests/generic/233
> > > > > @@ -43,6 +43,13 @@ _fsstress()
> > > > >  -f rename=10 -f fsync=2 -f write=15 -f dwrite=15 \
> > > > >  -n $count -d $out -p 7`
> > > > >  
> > > > > +	# io_uring accounts memory it needs under the rlimit memlocked option,
> > > > > +	# which can be quite low on some setups (especially 64K pagesize). root
> > > > > +	# isn't under this restriction, but regular users are. To avoid the
> > > > > +	# io_uring_queue_init fail on ENOMEM, set max locked memory to unlimited
> > > > > +	# temporarily.
> > > > > +	lmem=`ulimit -l`
> > > > > +	ulimit -l unlimited
> > > > 
> > > > Should this apply to all the other tests that run fsstress?
> > > > 
> > > > $ grep -l FSSTRESS_PROG tests/ | wc -l
> > > > 94
> > > 
> > > The root user isn't under this restriction, only g/233 and g/270 run fsstress
> > > with non-root user ($qa_user).
> > > Hmm... is that possible to run xfstests with a non-root user? Or you'd like to
> > 
> > No, fstests is required to be run by root user, there's a check in
> > 'check' script :)
> > 
> > > write a common helper _fsstress() (if run fsx with non-root user, I doubt it's
> > > needed too)...
> > 
> > Perhaps we should raise the limit in fsstress and fsx while setting up
> > io_uring_queue_init()? So we don't have to add this ulimit settings to
> > every test that runs fsstress/fsx with regular user.
> 
> Hmm... I don't know if it's the best idea, to change a sysconfig in fsstress.
> 
> If by any chance, in the future, someone case uses fsstress to test a sysconfig
> which is changed by fsstress :)

And fsstress is invoked by a regular user, and doesn't have the
permission to change rlimit..

Thanks,
Eryu