Re: [PATCH v6 1/6] selftests/mm/guard-regions: skip collapse test when thp not enabled

[Chunyu Hu <chuhu@redhat.com>]

On Fri, Mar 27, 2026 at 07:43:14AM +0000, Lorenzo Stoakes (Oracle) wrote:
> On Tue, Mar 24, 2026 at 09:33:11AM +0800, Chunyu Hu wrote:
> > When thp is not available, just skip the collape tests to avoid the false
> > negative.
> >
> > Without the change, run with a thp disabled kernel:
> >   ./run_vmtests.sh -t madv_guard -n 1
> >   <snip/>
> >   #  RUN           guard_regions.anon.collapse ...
> >   # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
> >   # collapse: Test terminated by assertion
> >   #          FAIL  guard_regions.anon.collapse
> >   not ok 2 guard_regions.anon.collapse
> >   <snip/>
> >   #  RUN           guard_regions.shmem.collapse ...
> >   # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
> >   # collapse: Test terminated by assertion
> >   #          FAIL  guard_regions.shmem.collapse
> >   not ok 32 guard_regions.shmem.collapse
> >   <snip/>
> >   #  RUN           guard_regions.file.collapse ...
> >   # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
> >   # collapse: Test terminated by assertion
> >   #          FAIL  guard_regions.file.collapse
> >   not ok 62 guard_regions.file.collapse
> >   <snip/>
> >   # FAILED: 87 / 90 tests passed.
> >   # 17 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
> >   # Totals: pass:70 fail:3 xfail:0 xpass:0 skip:17 error:0
> >
> > With this change, run with thp disabled kernel:
> >   ./run_vmtests.sh -t madv_guard -n 1
> >   <snip/>
> >   #  RUN           guard_regions.anon.collapse ...
> >   #      SKIP      Transparent Hugepages not available
> >   #            OK  guard_regions.anon.collapse
> >   ok 2 guard_regions.anon.collapse # SKIP Transparent Hugepages not available
> >   <snip/>
> >   #  RUN           guard_regions.file.collapse ...
> >   #      SKIP      Transparent Hugepages not available
> >   #            OK  guard_regions.file.collapse
> >   ok 62 guard_regions.file.collapse # SKIP Transparent Hugepages not available
> >   <snip/>
> >   #  RUN           guard_regions.shmem.collapse ...
> >   #      SKIP      Transparent Hugepages not available
> >   #            OK  guard_regions.shmem.collapse
> >   ok 32 guard_regions.shmem.collapse # SKIP Transparent Hugepages not available
> >   <snip/>
> >   # PASSED: 90 / 90 tests passed.
> >   # 20 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
> >   # Totals: pass:70 fail:0 xfail:0 xpass:0 skip:20 error:0
> >
> > Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> > Reviewed-by: Zi Yan <ziy@nvidia.com>
> > Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> > CC: Li Wang <liwang@redhat.com>
> > Signed-off-by: Chunyu Hu <chuhu@redhat.com>
> 
> Pretty sure I reviewed this already (but hey I forget to propagate tags myself
> sometimes so meh :P), anyway:
> 
> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Thanks for the review. Will add in next version.

> 
> Cheers, Lorenzo
> 
> > ---
> > Changes in v5:
> >   - updated reviewed-by and acked-by
> > Changes in v4:
> >   - use thp_available instead of thp_is_enabled() as when thp is set to
> >     never, madvise(MADV_COLLAPSE) will still succeed by design. So a
> >     failure in madvise(MADV_COLLAPSE) on guard region will verify guard
> >     region denies it. This is suggested from AI.
> >   - removed the 'Reviewed-by' and 'Acked-by' as the code changes. Sorry for
> >     that but it seems the changes is a little huge? (1 out of 2 lines)..
> > Changes in v3:
> >   - commit message: update the log snippet with where the fail happens and
> >     add the '-n1' to the command.
> >   - fix the 'false positive' to 'false negative'
> >   - add reviwed by from Mike
> > Changes in v2:
> >   - add reviewed by from Zi and Lorenzo
> >   - add acked-by from David
> > ---
> >  tools/testing/selftests/mm/guard-regions.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> > index dbd21d66d383..48e8b1539be3 100644
> > --- a/tools/testing/selftests/mm/guard-regions.c
> > +++ b/tools/testing/selftests/mm/guard-regions.c
> > @@ -21,6 +21,7 @@
> >  #include <sys/uio.h>
> >  #include <unistd.h>
> >  #include "vm_util.h"
> > +#include "thp_settings.h"
> >
> >  #include "../pidfd/pidfd.h"
> >
> > @@ -2195,6 +2196,9 @@ TEST_F(guard_regions, collapse)
> >  	char *ptr;
> >  	int i;
> >
> > +	if (!thp_available())
> > +		SKIP(return, "Transparent Hugepages not available\n");
> > +
> >  	/* Need file to be correct size for tests for non-anon. */
> >  	if (variant->backing != ANON_BACKED)
> >  		ASSERT_EQ(ftruncate(self->fd, size), 0);
> > --
> > 2.53.0
> >
>