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Thu, 2 May 2024 08:52:59 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, David Hildenbrand , Andrew Morton , Muchun Song , Shuah Khan Subject: [PATCH v1 0/2] selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL Date: Thu, 2 May 2024 10:52:57 +0200 Message-ID: <20240502085259.103784-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 X-Stat-Signature: h3quem3ybyrqdp7jdec76ffif5h67zxu X-Rspamd-Queue-Id: 19F4CA0030 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1714639985-97778 X-HE-Meta: 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 72QaABFB 3hW4rw9MjSDnpXLjUzEen2WhL0n6uPJc9OEEROr0d2G4aiRT+/OQbCSopgaFYNjYVEtadMaOVttaC1qjTGWHBTKoHSxrXTrrpAWLf+Fy+T+wO9379N3AzVr9C/Jnqj3Nx5NQ7BinHWzngK51xTccAXr2vpGY5bZh7+kmRPKJpiEuXl/bab6SCJLUwiFeUTLw35mrTAiIumRT7VYhYVwEdzMhVDh0ewLfkirctwejQ2CYrz6FWdPWrT4E1r8aJOXMQ1YT3+Qws++j85R99s1HD5gfTeHAKAGOfQOBz X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The failing hugetlb vmsplice() COW tests keep confusing people, and having tests that have been failing for years and likely will keep failing for years to come because nobody cares enough is rather suboptimal. Let's mark them as XFAIL and document why fixing them is not that easy as it would appear at first sight. More details can be found in [1], especially around how hugetlb pages cannot really be overcommitted, and why we don't particularly care about these vmsplice() leaks for hugetlb -- in contrast to ordinary memory. [1] https://lore.kernel.org/all/8b42a24d-caf0-46ef-9e15-0f88d47d2f21@redhat.com/ Cc: Andrew Morton Cc: Muchun Song Cc: Shuah Khan David Hildenbrand (2): selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL mm/hugetlb: document why hugetlb uses folio_mapcount() for COW reuse decisions mm/hugetlb.c | 7 ++ tools/testing/selftests/mm/cow.c | 106 +++++++++++++++++++++---------- 2 files changed, 78 insertions(+), 35 deletions(-)