Re: [PATCH 10/28] check-parallel: use PID namespaces for runner process isolation

[Dave Chinner <david@fromorbit.com>]

On Wed, May 07, 2025 at 02:32:29PM +0530, Nirjhar Roy (IBM) wrote:
> On Thu, 2025-04-17 at 13:00 +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > This provides isolation between individual runners so that they
> > cannot see the processes that other test runners have created.
> > This means tools like pkill will only find processes run by the test
> > that is calling it, hence there is no danger that it might kill
> > processes owned by a different test in a different runner context.
> > 
> > This means we need to turn of private pid/mount namespaces inside
> > check itself - nesting private namespaces causes all sorts of weird
> > TEST_DIR mount issues with SELinux disallowing TEST_DIR mounts.
> > 
> > Note that this also regresses generic/504 for check-parallel,
> > because it triggers looking at the init namespace from
> > FSTESTS_ISOL=privatens and this variable is not exported to test
> > subprocesses anymore.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  check-parallel | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> > 
> > diff --git a/check-parallel b/check-parallel
> > index 19f2d2b0c..aa88c681e 100755
> > --- a/check-parallel
> > +++ b/check-parallel
> > @@ -267,14 +267,18 @@ runner_go()
> >  	rm -f $RESULT_BASE/check.*
> >  
> >  	# Only supports default mkfs parameters right now
> > -	wipefs -a $TEST_DEV > /dev/null 2>&1
> > -	yes | mkfs -t $FSTYP $TEST_MKFS_OPTS $TEST_DEV > /dev/null 2>&1
> > +	wipefs -a $TEST_DEV > $me/log 2>&1
> > +	yes | mkfs -t $FSTYP $TEST_MKFS_OPTS $TEST_DEV >> $me/log 2>&1
> >  
> >  #	export DUMP_CORRUPT_FS=1
> >  
> >  	# Run the tests in it's own mount namespace, as per the comment below
> >  	# that precedes making the basedir a private mount.
> > -	./src/nsexec -m ./check $run_section -x unreliable_in_parallel --exact-order ${runner_list[$id]} > $me/log 2>&1
> > +	#
> > +	# Similarly, we need to run check in it's own PID namespace so that
> > +	# operations like pkill only affect the runner instance, not globally
> > +	# kill processes from other check instances.
> > +	tools/run_privatens ./check $run_section -x unreliable_in_parallel --exact-order ${runner_list[$id]} >> $me/log 2>&1
> Why aren't we using -s $section and only using $section with check?

It is already encoded in $run_section - the CLI parsing adds the -s
for each section that is specified on the command line:

        -s)     run_section="$run_section -s $2"; shift ;;

-Dave.

-- 
Dave Chinner
david@fromorbit.com