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Howlett" , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , SeongJae Park , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2] Docs/mm/damon/design: document DAMON actions when TRANSPARENT_HUGEPAGE is off Date: Tue, 17 Mar 2026 20:53:47 -0700 Message-ID: <20260318035349.88715-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AD05B1C0007 X-Stat-Signature: 1n69f1aef3iui46ka6qq5go16my4uiw1 X-Rspam-User: X-HE-Tag: 1773806043-748023 X-HE-Meta: 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 R6qkne3m 7afDDwVPtihKYvCCJj9rlToTA1T0MPBh4ufKoSbigLZhAFCYwi3pDcU+/xHlSv2XJV5BkOwyHdAnyu8itY1v/WCXFAZxBUg6atXvY9QOhXag4notuom9R7uufpYuk2XrSJVu/2q0cPLR4GGW6hs1kHJpOkGERSxk+H1/Rv1UsL6g4NneEfbkf4AYAJ+UJsKD55ehiNxvVuKSGDLMMsHCafiNrY2dA1z/4iwBuoZCarwQ4rBwgowKzJNzKU4toWQvXTEgNj4TFjEVJQ756cDWu0O+KB68GVJ5mAk9aTyHY5j/fCrrsBD23GMKX/TfC6W1rdgCfNWRkUWsi9NeDXzopPhNfew== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Asier Gutierrez MADV_HUGEPAGE and MADV_NOHUGEPAGE are guarded and they are not available when compiling the kernel without TRANSPARENT_HUGEPAGE option. The DAMON behaviour is to silently fail [1] in when DAMOS_HUGEPAGE or DAMOS_NOHUGEPAGE are used, but TRANSPARENT_HUGEPAGE is disabled. Update the DAMON documentation to reflect this behaviour. [1]: https://lore.kernel.org/66131775-180b-4b9f-b7ce-61a3e077b6e6@huawei-partners.com/ Signed-off-by: Asier Gutierrez Reviewed-by: SeongJae Park Signed-off-by: SeongJae Park --- Changes from v1 (https://lore.kernel.org/20260316140822.2033181-1-gutierrez.asier@huawei-partners.com) - Wordsmith description. - Rebase to latest mm-new. Documentation/mm/damon/design.rst | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index dc37402c0fee9..838b14d225193 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -460,9 +460,13 @@ that supports each action are as below. - ``pageout``: Reclaim the region. Supported by ``vaddr``, ``fvaddr`` and ``paddr`` operations set. - ``hugepage``: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``. - Supported by ``vaddr`` and ``fvaddr`` operations set. + Supported by ``vaddr`` and ``fvaddr`` operations set. When + TRANSPARENT_HUGEPAGE is disabled, the application of the action will just + fail. - ``nohugepage``: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``. - Supported by ``vaddr`` and ``fvaddr`` operations set. + Supported by ``vaddr`` and ``fvaddr`` operations set. When + TRANSPARENT_HUGEPAGE is disabled, the application of the action will just + fail. - ``lru_prio``: Prioritize the region on its LRU lists. Supported by ``paddr`` operations set. - ``lru_deprio``: Deprioritize the region on its LRU lists. base-commit: 809b8b9fc1374abb1b1b50fbd0260085b0832b2e -- 2.47.3