Re: [PATCH] mm/secretmem: properly account locked pages

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

On Tue, Aug 18, 2026 at 04:27:48PM +0100, Lorenzo Stoakes (ARM) wrote:
> On Tue, Aug 18, 2026 at 05:47:55PM +0300, Mike Rapoport wrote:
> > > diff --git a/tools/testing/selftests/mm/memfd_secret.c b/tools/testing/selftests/mm/memfd_secret.c
> > > index aac4f795c327..626e7033b72f 100644
> > > --- a/tools/testing/selftests/mm/memfd_secret.c
> > > +++ b/tools/testing/selftests/mm/memfd_secret.c
...
> > > +static void test_mlock_limit(void)
> > >  {
> > >  	size_t len;
> > >  	char *mem;
> > > +	int fd;
> > > +
> > > +	/* Locked pages have an inode lifetime, so need a new fd. */
> > > +	fd = memfd_secret(0);
> > > +	if (fd < 0) {
> > > +		fail("memfd_secret failed: %s\n", strerror(errno));
> > > +		return;
> > > +	}
> > > +
> > > +	if (ftruncate(fd, mlock_limit_max * 2)) {
> > > +		fail("ftruncate failed: %s\n", strerror(errno));
> > > +		goto out_close;
> > > +	}
> >
> > Can't we ftruncate to this size in main and be done?
>
> I think we should be able to, will change unless it's somehow a problem.

OK no, I have to do it here as there needs to be a new fd since keeping the same
fd would mean all future tests would have secretmem that exceeded the rlimit
quota (since it's per inode now), so have to set up new fd, configure it, tear
it down just for this test :)

--
Cheers, Lorenzo