On Mon, Nov 3, 2025 at 9:13 AM David Hildenbrand (Red Hat)
<[email protected]> wrote:
>
> On 28.10.25 22:24, Kalesh Singh wrote:
> > Add a new selftest to verify that the max VMA count limit is correctly
> > enforced.
> >
> > This test suite checks that various VMA operations (mmap, mprotect,
> > munmap, mremap) succeed or fail as expected when the number of VMAs is
> > close to the sysctl_max_map_count limit.
> >
> > The test works by first creating a large number of VMAs to bring the
> > process close to the limit, and then performing various operations that
> > may or may not create new VMAs. The test then verifies that the
> > operations that would exceed the limit fail, and that the operations
> > that do not exceed the limit succeed.
> >
> > NOTE: munmap is special as it's allowed to temporarily exceed the limit
> > by one for splits as this will decrease back to the limit once the unmap
> > succeeds.
> >
> > Cc: Andrew Morton <[email protected]>
> > Cc: David Hildenbrand <[email protected]>
> > Cc: "Liam R. Howlett" <[email protected]>
> > Cc: Lorenzo Stoakes <[email protected]>
> > Cc: Mike Rapoport <[email protected]>
> > Cc: Minchan Kim <[email protected]>
> > Cc: Pedro Falcato <[email protected]>
> > Signed-off-by: Kalesh Singh <[email protected]>
> > ---
>
> [...]
>
> No capacity to review the tests in detail :(
Appreciate you taking a look :)
>
> > +
> > diff --git a/tools/testing/selftests/mm/run_vmtests.sh
> > b/tools/testing/selftests/mm/run_vmtests.sh
> > index d9173f2312b7..a85db61e6a92 100755
> > --- a/tools/testing/selftests/mm/run_vmtests.sh
> > +++ b/tools/testing/selftests/mm/run_vmtests.sh
> > @@ -49,6 +49,8 @@ separated by spaces:
> > test madvise(2) MADV_GUARD_INSTALL and MADV_GUARD_REMOVE options
> > - madv_populate
> > test memadvise(2) MADV_POPULATE_{READ,WRITE} options
> > +- max_vma_count
> > + tests for max vma_count
> > - memfd_secret
> > test memfd_secret(2)
> > - process_mrelease
> > @@ -426,6 +428,9 @@ fi # VADDR64
> > # vmalloc stability smoke test
> > CATEGORY="vmalloc" run_test bash ./test_vmalloc.sh smoke
> >
> > +# test operations against max vma count limit
> > +CATEGORY="max_vma_count" run_test ./max_vma_count_tests
>
> I'd just call it CATEGORY="vma" or "vma_handling".
>
> Which makes me wodnering whether "vma_merge" falls into the same category.
>
> Smalls like mremap test is similar.
>
> Point is that "CATEGORY" stops being really useful if we end up having a
> separate category for each test, right? :)
I agree making both use a "vma" category seem more helpful. I'll wait
for others' feedback before resending.
Thanks,
Kalesh
>
> --
> Cheers
>
> David
