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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CE6278000D X-Stat-Signature: hfmcwzmhawihn5aah9gy3s7eybxc69nj X-Rspam-User: X-HE-Tag: 1789084982-873793 X-HE-Meta: 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 onv/hbRx 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 10, 2026 at 4:24=E2=80=AFPM Andrew Morton wrote: > Sashiko had a stupid niggle about the selftest change and made quite > disturbing claims about the existing try_collapse_pte_mapped_thp() code: > > https://sashiko.dev/#/patchset/20260910023411.514987-1-jthoughton= @google.com Thanks, it looks like the note it wrote about the selftest is genuine; it i= s okay for MADV_COLLAPSE to fail. So I shouldn't have changed uffd_test_skip(= ) to uffd_test_fail(). Andrew, if you can, please add this diff as part of the patch to queue. (It= 's a partial revert.) Or I could send the a new version of the patch as a repl= y to patch #2 email. Or a whole v4, whatever's easiest. diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/s= elftests/mm/uffd-unit-tests.c index 6f2360f9b75d..d8e40b770d88 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -639,7 +639,8 @@ static void uffd_minor_test_common(uffd_global_test_opt= s_t *gopts, bool test_col /* MADV_COLLAPSE should succeed with userfaultfd unregistered. */ if (madvise(gopts->area_dst_alias, gopts->nr_pages * gopts->page_size, MADV_COLLAPSE)) { - uffd_test_fail("MADV_COLLAPSE failed"); + /* It's fine to fail for this one... */ + uffd_test_skip("MADV_COLLAPSE failed"); return; } =20 With respect to the note about try_collapse_pte_mapped_thp() breaking POSIX SIGBUS semantics, it definitely seems plausible. I'll look into it. > I'll queue the series for test-n-review. Thanks!