+ mm-damon-reclaim-support-addr_unit-for-damon_reclaim.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/damon/reclaim: support addr_unit for DAMON_RECLAIM
has been added to the -mm mm-new branch.  Its filename is
     mm-damon-reclaim-support-addr_unit-for-damon_reclaim.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-reclaim-support-addr_unit-for-damon_reclaim.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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------------------------------------------------------
From: Quanmin Yan <yanquanmin1@huawei.com>
Subject: mm/damon/reclaim: support addr_unit for DAMON_RECLAIM
Date: Wed, 10 Sep 2025 19:32:21 +0800

Implement a sysfs file to expose addr_unit for DAMON_RECLAIM users. 
During parameter application, use the configured addr_unit parameter to
perform the necessary initialization.  Similar to the core layer, prevent
setting addr_unit to zero.

It is worth noting that when monitor_region_start and monitor_region_end
are unset (i.e., 0), their values will later be set to biggest_system_ram.
At that point, addr_unit may not be the default value 1.  Although we
could divide the biggest_system_ram value by addr_unit, changing addr_unit
without setting monitor_region_start/end should be considered a user
misoperation.  And biggest_system_ram is only within the 0~ULONG_MAX
range, system can clearly work correctly with addr_unit=1.  Therefore, if
monitor_region_start/end are unset, always silently reset addr_unit to 1.

Link: https://lkml.kernel.org/r/20250910113221.1065764-3-yanquanmin1@huawei.com
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: ze zuo <zuoze1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/reclaim.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

--- a/mm/damon/reclaim.c~mm-damon-reclaim-support-addr_unit-for-damon_reclaim
+++ a/mm/damon/reclaim.c
@@ -129,6 +129,13 @@ static unsigned long monitor_region_end
 module_param(monitor_region_end, ulong, 0600);
 
 /*
+ * Scale factor for DAMON_RECLAIM to ops address conversion.
+ *
+ * This parameter must not be set to 0.
+ */
+static unsigned long addr_unit __read_mostly = 1;
+
+/*
  * Skip anonymous pages reclamation.
  *
  * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
@@ -194,6 +201,15 @@ static int damon_reclaim_apply_parameter
 	if (err)
 		return err;
 
+	/*
+	 * If monitor_region_start/end are unset, always silently
+	 * reset addr_unit to 1.
+	 */
+	if (!monitor_region_start && !monitor_region_end)
+		addr_unit = 1;
+	param_ctx->addr_unit = addr_unit;
+	param_ctx->min_sz_region = max(DAMON_MIN_REGION / addr_unit, 1);
+
 	if (!damon_reclaim_mon_attrs.aggr_interval) {
 		err = -EINVAL;
 		goto out;
@@ -294,6 +310,30 @@ static int damon_reclaim_turn(bool on)
 	return damon_call(ctx, &call_control);
 }
 
+static int damon_reclaim_addr_unit_store(const char *val,
+		const struct kernel_param *kp)
+{
+	unsigned long input_addr_unit;
+	int err = kstrtoul(val, 0, &input_addr_unit);
+
+	if (err)
+		return err;
+	if (!input_addr_unit)
+		return -EINVAL;
+
+	addr_unit = input_addr_unit;
+	return 0;
+}
+
+static const struct kernel_param_ops addr_unit_param_ops = {
+	.set = damon_reclaim_addr_unit_store,
+	.get = param_get_ulong,
+};
+
+module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600);
+MODULE_PARM_DESC(addr_unit,
+	"Scale factor for DAMON_RECLAIM to ops address conversion (default: 1)");
+
 static int damon_reclaim_enabled_store(const char *val,
 		const struct kernel_param *kp)
 {
_

Patches currently in -mm which might be from yanquanmin1@huawei.com are

mm-damon-add-damon_ctx-min_sz_region.patch
mm-damon-lru_sort-support-addr_unit-for-damon_lru_sort.patch
mm-damon-reclaim-support-addr_unit-for-damon_reclaim.patch