On Thu, Mar 06, 2025 at 10:05:13PM +1100, Dave Chinner wrote:
> On Thu, Mar 06, 2025 at 05:49:23PM +0800, Zorro Lang wrote:
> > Currently we have 3 ways to run a test case in _run_seq():
> >
> > if [ -n "${HAVE_PRIVATENS}" ]; then
> > ./tools/run_privatens "./$seq"
> > ...
> > elif [ -n "${HAVE_SYSTEMD_SCOPES}" ]; then
> > systemd-run --quiet --unit "${unit}" --scope \
> > ./tools/run_setsid "./$seq" &
> > ...
> > else
> > ./tools/run_setsid "./$seq" &
> > ...
> > fi
> >
> > The "privatens" way brings in some regressions. We need more time
> > to develop and test this way, it's not time let it to be the
> > first default choice, so isolate the HAVE_PRIVATENS initialization
> > by a TRY_PRIVATENS parameter, and disable it by default.
> >
> > Set TRY_PRIVATENS=yes to give "privatens" a try, otherwise run in
> > old ways. This patch can be removed after "privatens" way is stable.
> >
> > Signed-off-by: Zorro Lang <zlang@xxxxxxxxxx>
> > Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
> > ---
> > check | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/check b/check
> > index ea92b0d62..cb2f19d08 100755
> > --- a/check
> > +++ b/check
> > @@ -674,10 +674,13 @@ _stash_test_status() {
> > esac
> > }
> >
> > -# Can we run in a private pid/mount namespace?
> > -HAVE_PRIVATENS=
> > -./tools/run_privatens bash -c "exit 77"
> > -test $? -eq 77 && HAVE_PRIVATENS=yes
> > +# Don't try "privatens" by default, it's experimental for now.
> > +if [ "$TRY_PRIVATENS" = "yes" ];then
> > + # Can we run in a private pid/mount namespace?
> > + HAVE_PRIVATENS=
> > + ./tools/run_privatens bash -c "exit 77"
> > + test $? -eq 77 && HAVE_PRIVATENS=yes
> > +fi
>
> Works for me - I have basically the same patch in my check-parallel
> stack because this breaks check-parallel mount namespacing for
> reasons I don't yet understand.
>
> Creating a new mount namespace for each test that is run appears
> to turn the private mount namespace that each check instance is
> executed in back into a globally shared mount namespace inside
> each individual test mount namespace.
>
> i.e. when check uses private namespaces I can see all the mounts
> from inside each test namespace from the init namespace and every
> test can see every mount that every other test runs again.
>
> That is the problem I originally used mount namespaces in
> check-parallel to avoid.
>
> I have no idea if this is how mount namespace nesting is actually
> supposed to work (seems completely broken to me!), but the only
> solution I've found that works so far is to turn off HAVE_PRIVATENS
> in check as it is redundant when it is run from check-parallel.
>
> FWIW, given that check-parallel now runs in it's own private PID
> namespace with it's own /proc and /tmp, the original problem of
> needing to "confine pkill to only the child processes of this test
> instance" has gone away entirely. i.e. check-parallel does not need check to
> to restrict pkill to children of the current test being run anymore.
>
> Hence I think we can probably remove the new process isolation
> shenanigans and revert the _pkill wrappers to plain pkill calls
> again as the private PID namespacing the check-parallel does means
> pkill does the right thing for both check and check-parallel now.
Hi Dave,
Thanks for your reviewing. Do you mean revert below commit directly?
commit 247ab01fa227647c290cf82696f1b0bbf87a0177
Author: Darrick J. Wong <djwong@xxxxxxxxxx>
Date: Mon Feb 3 14:00:28 2025 -0800
check: run tests in a private pid/mount namespace
I isolate the HAVE_PRIVATENS rather than reverting it, due to I'm not
sure if you or Darrick still would like to improve that test way.
Thanks,
Zorro
>
> -Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
>
