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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] kselftest: mm: prevent random failure of huge page split for khugepaged Message-ID: References: <20260826-fix_split-v2-0-71153c7f579a@arm.com> <20260826-fix_split-v2-1-71153c7f579a@arm.com> <36c54170-f7cb-4b1e-a1fd-50544390632b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <36c54170-f7cb-4b1e-a1fd-50544390632b@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0A438140006 X-Stat-Signature: kmor8hipn38ih1akfphdg77f8wysekqx X-HE-Tag: 1787829095-551558 X-HE-Meta: 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 sveB/v23 kijLG6PkSH5jmJb6CTg5av/o7U25IOUz1I9b0wseKWbUbN3fEmVbl5BaaxeG+QKLb+/KqIgv6/OWeA+dKpuyoYOIH3uu08LAdPq6mdh8eszWUNa+9cid0Gy/uQVKpBrCjjjc5qaGU9VAhm6Pnkw0qEHp6wyKGUYX+EerzwwMoZVlz9NtMWYMuuseDOBav+JybvQTo+csa5wNIqnpXTkpia5QOmfkI/DS5/9AtP0Fwo9xOhhLdtgwS0bGGJb9UOEw21xMX9cXC+1hnGA09pVJ4SWQT7IcXMaqZDS3QqgQHBem3/mSyqZ94gr6dFzUkliFvY6vL Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On 8/26/26 14:24, Yeoreum Yun wrote: > > There're some random failure for split_huge_page_test when khugepaged > > collapses pages into pmd again which had split by the test. > > > > Prevent the khugepaged's collapses for split page by setting the > > mapped pmd-huge-page with MADV_NOHUGEPAGE before split. > > > > Reported-by: Kevin Brodsky > > Reviewed-by: Zi Yan > > Signed-off-by: Yeoreum Yun > > --- > > tools/testing/selftests/mm/split_huge_page_test.c | 15 +++++++++++++++ > > 1 file changed, 15 insertions(+) > > > > diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c > > index 86a603692826..8f68bc94a5ca 100644 > > --- a/tools/testing/selftests/mm/split_huge_page_test.c > > +++ b/tools/testing/selftests/mm/split_huge_page_test.c > > @@ -180,6 +180,10 @@ static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hp > > if (!rss_anon_before) > > ksft_exit_fail_msg("No RssAnon is allocated before split\n"); > > > > + /* Prevent khugepaged from collapsing the pages. */ > > + if (madvise(one_page, len, MADV_NOHUGEPAGE)) > > + ksft_print_msg("MADV_NOHUGEPAGE failed to prevent khugepaged from collapsing pages.\n"); > > + > > Ok, this is really only expected to fail on extremely old kernels or kernels > without CONFIG_TRANSPARENT_HUGEPAGE (where we should never get to that point :) ). > > Can we just turn that into a > ksft_exit_fail_perror("madvise(MADV_NOHUGEPAGE)"); > > I'm okay with a ksft_print_msg() as well, but would shorten the message quite a > lot ("MADV_NOHUGEPAGE failed" or sth). Thanks. I'll change the message only then. -- Sincerely, Yeoreum Yun