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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Shuah Khan References: <20260921-fix_khugepagd_fail-v2-0-3c2877beef61@arm.com> <20260921-fix_khugepagd_fail-v2-1-3c2877beef61@arm.com> From: Baolin Wang In-Reply-To: <20260921-fix_khugepagd_fail-v2-1-3c2877beef61@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3EB26100002 X-Stat-Signature: 9n8gen7s8p9gaauifb4gxine6o9pgx8x X-HE-Tag: 1790134454-415496 X-HE-Meta: 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 nGgMuNCm g+Pc8xOQK9LvBDDXH26l8Tq+oNDSjJ/tZU5JJVQ7/UgmHo75xVnuxtOUSCflCmeYNFK+9sEaBuSSakwmkwsxO0y5Ky/KZ66guZCEwL8Ve/dBQlHfAW0o123Uac/od76yMPq/tOYFBNnstR/CJQqptVleog0TMrELRpxCzV+hDtV7nQXzHaPvrYZNLpzJrMOwNhO87Vl2FrfbfNvVI4L5LJU9XMOuN63GcaCT97cyvHppVVsVskgFneWBGdyiyV7AwZnWk0ndJ4qPJovkYqKMoZoySoYMoQ19kcLaSSiGcxSZ8cgzvOdk5btbNCvkV6LG2FpM+X1+I/wlUNk0klFjN1jAoktM1f2qvnuu5y83W2dtaI9qcHXeKp2nO7Ba1jTdr6bkD Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/21/26 6:35 PM, Yeoreum Yun wrote: > Although the child process in collapse_fork*() or collapse_max_ptes_shared() > reports `KSFT_FAIL`, the result is ignored because the test only checks > whether the parent’s page was collapsed into a huge page. > > As a result, the test is considered successful whenever the parent’s page > is a huge page, even if the child test fails, as shown below: > > # > # Run test: collapse_max_ptes_shared (khugepaged:anon) > # Allocate huge page... OK > # Share huge page over fork()... OK > # Trigger CoW on page 1023 of 2048... OK > # Maybe collapse with max_ptes_shared exceeded.... OK > # Trigger CoW on page 1024 of 2048... Fail > Bail out! Unexpected huge page > # Planned tests != run tests (26 != 23) > # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 // child failed. > # Check if parent still has huge page... OK // parent hpage success > ok 24 collapse_max_ptes_shared // considered as success > ... > # Totals: pass:26 fail:0 xfail:0 xpass:0 skip:0 error:0 > > To address this, propagate the child’s failure and skip the subsequent > check in the parent. > > Signed-off-by: Yeoreum Yun > --- Make sense to me. Reviewed-by: Baolin Wang