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Wed, 01 Jul 2026 04:47:39 -0700 (PDT) Received: from localhost.localdomain ([2607:f130:0:11a::31]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30ee327cea7sm22518169eec.31.2026.07.01.04.47.36 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 01 Jul 2026 04:47:38 -0700 (PDT) From: wang lian To: damon@lists.linux.dev, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, sj@kernel.org, gutierrez.asier@huawei-partners.com, daichaobing@sangfor.com.cn, lianux.wang@processmission.com, Wang Lian Subject: [PATCH v2 4/5] mm/damon: introduce DAMOS_SPLIT action Date: Wed, 1 Jul 2026 19:47:15 +0800 Message-ID: <20260701114716.56503-5-lianux.mm@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260701114716.56503-1-lianux.mm@gmail.com> References: <20260701114716.56503-1-lianux.mm@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Wang Lian Add DAMOS_SPLIT to the damos_action enum for splitting large folios into smaller mTHP-order folios. Add a target_order field to struct damos to specify the desired split order. Expose the action as "split" through the DAMON sysfs interface with target_order validation (must be 2..HPAGE_PMD_ORDER-1). Signed-off-by: Wang Lian Signed-off-by: Wang Lian --- include/linux/damon.h | 9 +++++++-- mm/damon/sysfs-schemes.c | 12 ++++++++++++ 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/include/linux/damon.h b/include/linux/damon.h index 5a0587556573..30cf4afb212c 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -121,6 +121,7 @@ struct damon_target { * @DAMOS_HUGEPAGE: Call ``madvise()`` for the region with MADV_HUGEPAGE. * @DAMOS_NOHUGEPAGE: Call ``madvise()`` for the region with MADV_NOHUGEPAGE. * @DAMOS_COLLAPSE: Call ``madvise()`` for the region with MADV_COLLAPSE. + * @DAMOS_SPLIT: Split large folios to the target mTHP order. * @DAMOS_LRU_PRIO: Prioritize the region on its LRU lists. * @DAMOS_LRU_DEPRIO: Deprioritize the region on its LRU lists. * @DAMOS_MIGRATE_HOT: Migrate the regions prioritizing warmer regions. @@ -141,6 +142,7 @@ enum damos_action { DAMOS_HUGEPAGE, DAMOS_NOHUGEPAGE, DAMOS_COLLAPSE, + DAMOS_SPLIT, DAMOS_LRU_PRIO, DAMOS_LRU_DEPRIO, DAMOS_MIGRATE_HOT, @@ -573,8 +575,11 @@ struct damos { struct damos_access_pattern pattern; enum damos_action action; /* - * @target_order: target order for mTHP actions (DAMOS_COLLAPSE). - * 0 means system default (PMD order). Valid: 0, 2..HPAGE_PMD_ORDER. + * @target_order: target mTHP order for DAMOS_COLLAPSE and + * DAMOS_SPLIT. For COLLAPSE, 0 means PMD order default, + * valid values: 0, 2..HPAGE_PMD_ORDER. For SPLIT, + * valid values: 2..HPAGE_PMD_ORDER-1; 0 and HPAGE_PMD_ORDER + * are rejected at scheme creation time (defaulting to 2). */ unsigned int target_order; unsigned long apply_interval_us; diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 735970717048..547252fc8a20 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -2293,6 +2293,10 @@ static struct damos_sysfs_action_name damos_sysfs_action_names[] = { .action = DAMOS_COLLAPSE, .name = "collapse", }, + { + .action = DAMOS_SPLIT, + .name = "split", + }, { .action = DAMOS_LRU_PRIO, .name = "lru_prio", @@ -3048,6 +3052,14 @@ static struct damos *damon_sysfs_mk_scheme( HPAGE_PMD_ORDER, HPAGE_PMD_ORDER); sysfs_scheme->target_order = 0; } + if (sysfs_scheme->action == DAMOS_SPLIT && + (sysfs_scheme->target_order == 0 || + sysfs_scheme->target_order >= HPAGE_PMD_ORDER)) { + pr_warn("DAMON split: target_order %u invalid, need 2..%u. Defaulting to 2.\n", + sysfs_scheme->target_order, + HPAGE_PMD_ORDER - 1); + sysfs_scheme->target_order = 2; + } scheme->target_order = sysfs_scheme->target_order; err = damos_sysfs_add_quota_score(sysfs_quotas->goals, &scheme->quota); -- 2.50.1 (Apple Git-155)