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Wed, 01 Jul 2026 04:47:28 -0700 (PDT) Received: from localhost.localdomain ([2607:f130:0:11a::31]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30ee327cea7sm22518169eec.31.2026.07.01.04.47.24 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 01 Jul 2026 04:47:28 -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 , Kunwu Chan Subject: [PATCH v2 1/5] mm/damon: add target_order field for DAMOS_COLLAPSE Date: Wed, 1 Jul 2026 19:47:12 +0800 Message-ID: <20260701114716.56503-2-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 DAMOS_COLLAPSE currently collapses into PMD-size THP only. Add a target_order field to express per-order mTHP collapse intent. Zero means system default (PMD order, same as current behavior). Valid values are 0 and 2..HPAGE_PMD_ORDER. Wire up the sysfs interface: a per-scheme rw file "target_order". Validate at store time that the value is in range, and warn at scheme creation time if DAMOS_COLLAPSE is used with an unsupported non-PMD order, resetting to 0. The actual mTHP application via the khugepaged wrapper will be added in subsequent patches. Co-developed-by: Kunwu Chan Signed-off-by: Kunwu Chan Signed-off-by: Wang Lian Signed-off-by: Wang Lian --- include/linux/damon.h | 5 +++++ mm/damon/sysfs-schemes.c | 45 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/include/linux/damon.h b/include/linux/damon.h index 6f7edb3590ef..5a0587556573 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -572,6 +572,11 @@ struct damos_migrate_dests { 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. + */ + unsigned int target_order; unsigned long apply_interval_us; /* private: internal use only */ /* diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 329cfd0bbe9f..735970717048 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -6,7 +6,9 @@ */ #include +#include #include +#include #include "sysfs-common.h" @@ -2257,6 +2259,7 @@ struct damon_sysfs_scheme { struct damon_sysfs_stats *stats; struct damon_sysfs_scheme_regions *tried_regions; int target_nid; + unsigned int target_order; struct damos_sysfs_dests *dests; }; @@ -2642,6 +2645,34 @@ static ssize_t target_nid_store(struct kobject *kobj, return err ? err : count; } +static ssize_t target_order_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct damon_sysfs_scheme *scheme = container_of(kobj, + struct damon_sysfs_scheme, kobj); + + return sysfs_emit(buf, "%u\n", scheme->target_order); +} + +static ssize_t target_order_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + struct damon_sysfs_scheme *scheme = container_of(kobj, + struct damon_sysfs_scheme, kobj); + unsigned int val; + int err; + + err = kstrtouint(buf, 0, &val); + if (err) + return err; + + if (val != 0 && (val < 2 || val > HPAGE_PMD_ORDER)) + return -EINVAL; + + scheme->target_order = val; + return count; +} + static void damon_sysfs_scheme_release(struct kobject *kobj) { kfree(container_of(kobj, struct damon_sysfs_scheme, kobj)); @@ -2656,10 +2687,14 @@ static struct kobj_attribute damon_sysfs_scheme_apply_interval_us_attr = static struct kobj_attribute damon_sysfs_scheme_target_nid_attr = __ATTR_RW_MODE(target_nid, 0600); +static struct kobj_attribute damon_sysfs_scheme_target_order_attr = + __ATTR_RW_MODE(target_order, 0600); + static struct attribute *damon_sysfs_scheme_attrs[] = { &damon_sysfs_scheme_action_attr.attr, &damon_sysfs_scheme_apply_interval_us_attr.attr, &damon_sysfs_scheme_target_nid_attr.attr, + &damon_sysfs_scheme_target_order_attr.attr, NULL, }; ATTRIBUTE_GROUPS(damon_sysfs_scheme); @@ -3005,6 +3040,16 @@ static struct damos *damon_sysfs_mk_scheme( if (!scheme) return NULL; + if (sysfs_scheme->action == DAMOS_COLLAPSE && + sysfs_scheme->target_order != 0 && + sysfs_scheme->target_order != HPAGE_PMD_ORDER) { + pr_warn("DAMON collapse: target_order %u not supported, only PMD order (%u) is available. Use 0 or %u.\n", + sysfs_scheme->target_order, + HPAGE_PMD_ORDER, HPAGE_PMD_ORDER); + sysfs_scheme->target_order = 0; + } + scheme->target_order = sysfs_scheme->target_order; + err = damos_sysfs_add_quota_score(sysfs_quotas->goals, &scheme->quota); if (err) { damon_destroy_scheme(scheme); -- 2.50.1 (Apple Git-155)