linux-kernel - Re: [PATCH v3 05/13] mm/damon/sysfs: Support the physical address space monitoring

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Date:   Tue, 1 Mar 2022 00:11:12 +0800
From:   xhao@...ux.alibaba.com
To:     SeongJae Park <sj@...nel.org>, akpm@...ux-foundation.org
Cc:     corbet@....net, skhan@...uxfoundation.org, rientjes@...gle.com,
        gregkh@...uxfoundation.org, linux-damon@...zon.com,
        linux-mm@...ck.org, linux-doc@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 05/13] mm/damon/sysfs: Support the physical address
 space monitoring


On 2/28/22 4:13 PM, SeongJae Park wrote:
> This commit makes DAMON sysfs interface supports the physical address
> space monitoring.  Specifically, this commit adds support of the initial
> monitoring regions set feature by adding 'regions' directory under each
> target directory and makes context operations file to receive 'paddr' in
> addition to 'vaddr'.
>
> As a result, the files hierarchy becomes as below:
>
>      /sys/kernel/mm/damon/admin
>      │ kdamonds/nr_kdamonds
>      │ │ 0/state,pid
>      │ │ │ contexts/nr_contexts
>      │ │ │ │ 0/operations
>      │ │ │ │ │ monitoring_attrs/
>      │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
>      │ │ │ │ │ │ nr_regions/min,max
>      │ │ │ │ │ targets/nr_targets
>      │ │ │ │ │ │ 0/pid_target
>      │ │ │ │ │ │ │ regions/nr_regions    <- NEW DIRECTORY
>      │ │ │ │ │ │ │ │ 0/start,end
>      │ │ │ │ │ │ │ │ ...
>      │ │ │ │ │ │ ...
>      │ │ │ │ ...
>      │ │ ...
>
> Signed-off-by: SeongJae Park <sj@...nel.org>
> ---
>   mm/damon/sysfs.c | 276 ++++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 271 insertions(+), 5 deletions(-)
>
> diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
> index 9221c93db6cc..968a4ba8e81b 100644
> --- a/mm/damon/sysfs.c
> +++ b/mm/damon/sysfs.c
> @@ -113,12 +113,220 @@ static struct kobj_type damon_sysfs_ul_range_ktype = {
>   	.default_groups = damon_sysfs_ul_range_groups,
>   };
>   
> +/*
> + * init region directory
> + */
> +
> +struct damon_sysfs_region {
> +	struct kobject kobj;
> +	unsigned long start;
> +	unsigned long end;
> +};
> +
> +static struct damon_sysfs_region *damon_sysfs_region_alloc(
> +		unsigned long start,
> +		unsigned long end)
> +{
> +	struct damon_sysfs_region *region = kmalloc(sizeof(*region),
> +			GFP_KERNEL);
> +
> +	if (!region)
> +		return NULL;
> +	region->kobj = (struct kobject){};
> +	region->start = start;
> +	region->end = end;
> +	return region;
> +}
> +

The interface "start" and "end" have the same problems

[root@...k03395 0]# echo 100 > start
[root@...k03395 0]# echo 10 > end
[root@...k03395 0]# cat end
10
[root@...k03395 0]# cat start
100

> +static ssize_t start_show(struct kobject *kobj, struct kobj_attribute *attr,
> +		char *buf)
> +{
> +	struct damon_sysfs_region *region = container_of(kobj,
> +			struct damon_sysfs_region, kobj);
> +
> +	return sysfs_emit(buf, "%lu\n", region->start);
> +}
> +
> +static ssize_t start_store(struct kobject *kobj, struct kobj_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct damon_sysfs_region *region = container_of(kobj,
> +			struct damon_sysfs_region, kobj);
> +	int err = kstrtoul(buf, 0, &region->start);
> +
> +	if (err)
> +		return -EINVAL;
> +	return count;
> +}
> +
> +static ssize_t end_show(struct kobject *kobj, struct kobj_attribute *attr,
> +		char *buf)
> +{
> +	struct damon_sysfs_region *region = container_of(kobj,
> +			struct damon_sysfs_region, kobj);
> +
> +	return sysfs_emit(buf, "%lu\n", region->end);
> +}
> +
> +static ssize_t end_store(struct kobject *kobj, struct kobj_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct damon_sysfs_region *region = container_of(kobj,
> +			struct damon_sysfs_region, kobj);
> +	int err = kstrtoul(buf, 0, &region->end);
> +
> +	if (err)
> +		return -EINVAL;
> +	return count;
> +}
> +
> +static void damon_sysfs_region_release(struct kobject *kobj)
> +{
> +	kfree(container_of(kobj, struct damon_sysfs_region, kobj));
> +}
> +
> +static struct kobj_attribute damon_sysfs_region_start_attr =
> +		__ATTR_RW_MODE(start, 0600);
> +
> +static struct kobj_attribute damon_sysfs_region_end_attr =
> +		__ATTR_RW_MODE(end, 0600);
> +
> +static struct attribute *damon_sysfs_region_attrs[] = {
> +	&damon_sysfs_region_start_attr.attr,
> +	&damon_sysfs_region_end_attr.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(damon_sysfs_region);
> +
> +static struct kobj_type damon_sysfs_region_ktype = {
> +	.release = damon_sysfs_region_release,
> +	.sysfs_ops = &kobj_sysfs_ops,
> +	.default_groups = damon_sysfs_region_groups,
> +};
> +
> +/*
> + * init_regions directory
> + */
> +
> +struct damon_sysfs_regions {
> +	struct kobject kobj;
> +	struct damon_sysfs_region **regions_arr;
> +	int nr;
> +};
> +
> +static struct damon_sysfs_regions *damon_sysfs_regions_alloc(void)
> +{
> +	return kzalloc(sizeof(struct damon_sysfs_regions), GFP_KERNEL);
> +}
> +
> +static void damon_sysfs_regions_rm_dirs(struct damon_sysfs_regions *regions)
> +{
> +	struct damon_sysfs_region **regions_arr = regions->regions_arr;
> +	int i;
> +
> +	for (i = 0; i < regions->nr; i++)
> +		kobject_put(&regions_arr[i]->kobj);
> +	regions->nr = 0;
> +	kfree(regions_arr);
> +	regions->regions_arr = NULL;
> +}
> +
> +static int damon_sysfs_regions_add_dirs(struct damon_sysfs_regions *regions,
> +		int nr_regions)
> +{
> +	struct damon_sysfs_region **regions_arr, *region;
> +	int err, i;
> +
> +	damon_sysfs_regions_rm_dirs(regions);
> +	if (!nr_regions)
> +		return 0;
> +
> +	regions_arr = kmalloc_array(nr_regions, sizeof(*regions_arr),
> +			GFP_KERNEL | __GFP_NOWARN);
> +	if (!regions_arr)
> +		return -ENOMEM;
> +	regions->regions_arr = regions_arr;
> +
> +	for (i = 0; i < nr_regions; i++) {
> +		region = damon_sysfs_region_alloc(0, 0);
> +		if (!region) {
> +			damon_sysfs_regions_rm_dirs(regions);
> +			return -ENOMEM;
> +		}
> +
> +		err = kobject_init_and_add(&region->kobj,
> +				&damon_sysfs_region_ktype, &regions->kobj,
> +				"%d", i);
> +		if (err) {
> +			kobject_put(&region->kobj);
> +			damon_sysfs_regions_rm_dirs(regions);
> +			return err;
> +		}
> +
> +		regions_arr[i] = region;
> +		regions->nr++;
> +	}
> +	return 0;
> +}
> +
> +static ssize_t nr_regions_show(struct kobject *kobj,
> +		struct kobj_attribute *attr, char *buf)
> +{
> +	struct damon_sysfs_regions *regions = container_of(kobj,
> +			struct damon_sysfs_regions, kobj);
> +
> +	return sysfs_emit(buf, "%d\n", regions->nr);
> +}
> +
> +static ssize_t nr_regions_store(struct kobject *kobj,
> +		struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> +	struct damon_sysfs_regions *regions = container_of(kobj,
> +			struct damon_sysfs_regions, kobj);
> +	int nr, err = kstrtoint(buf, 0, &nr);
> +
> +	if (err)
> +		return err;
> +	if (nr < 0)
> +		return -EINVAL;
> +
> +	if (!mutex_trylock(&damon_sysfs_lock))
> +		return -EBUSY;
> +	err = damon_sysfs_regions_add_dirs(regions, nr);
> +	mutex_unlock(&damon_sysfs_lock);
> +	if (err)
> +		return err;
> +
> +	return count;
> +}
> +
> +static void damon_sysfs_regions_release(struct kobject *kobj)
> +{
> +	kfree(container_of(kobj, struct damon_sysfs_regions, kobj));
> +}
> +
> +static struct kobj_attribute damon_sysfs_regions_nr_attr =
> +		__ATTR_RW_MODE(nr_regions, 0600);
> +
> +static struct attribute *damon_sysfs_regions_attrs[] = {
> +	&damon_sysfs_regions_nr_attr.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(damon_sysfs_regions);
> +
> +static struct kobj_type damon_sysfs_regions_ktype = {
> +	.release = damon_sysfs_regions_release,
> +	.sysfs_ops = &kobj_sysfs_ops,
> +	.default_groups = damon_sysfs_regions_groups,
> +};
> +
>   /*
>    * target directory
>    */
>   
>   struct damon_sysfs_target {
>   	struct kobject kobj;
> +	struct damon_sysfs_regions *regions;
>   	int pid;
>   };
>   
> @@ -127,6 +335,29 @@ static struct damon_sysfs_target *damon_sysfs_target_alloc(void)
>   	return kzalloc(sizeof(struct damon_sysfs_target), GFP_KERNEL);
>   }
>   
> +static int damon_sysfs_target_add_dirs(struct damon_sysfs_target *target)
> +{
> +	struct damon_sysfs_regions *regions = damon_sysfs_regions_alloc();
> +	int err;
> +
> +	if (!regions)
> +		return -ENOMEM;
> +
> +	err = kobject_init_and_add(&regions->kobj, &damon_sysfs_regions_ktype,
> +			&target->kobj, "regions");
> +	if (err)
> +		kobject_put(&regions->kobj);
> +	else
> +		target->regions = regions;
> +	return err;
> +}
> +
> +static void damon_sysfs_target_rm_dirs(struct damon_sysfs_target *target)
> +{
> +	damon_sysfs_regions_rm_dirs(target->regions);
> +	kobject_put(&target->regions->kobj);
> +}
> +
>   static ssize_t pid_target_show(struct kobject *kobj,
>   		struct kobj_attribute *attr, char *buf)
>   {
> @@ -188,8 +419,10 @@ static void damon_sysfs_targets_rm_dirs(struct damon_sysfs_targets *targets)
>   	struct damon_sysfs_target **targets_arr = targets->targets_arr;
>   	int i;
>   
> -	for (i = 0; i < targets->nr; i++)
> +	for (i = 0; i < targets->nr; i++) {
> +		damon_sysfs_target_rm_dirs(targets_arr[i]);
>   		kobject_put(&targets_arr[i]->kobj);
> +	}
>   	targets->nr = 0;
>   	kfree(targets_arr);
>   	targets->targets_arr = NULL;
> @@ -224,6 +457,10 @@ static int damon_sysfs_targets_add_dirs(struct damon_sysfs_targets *targets,
>   		if (err)
>   			goto out;
>   
> +		err = damon_sysfs_target_add_dirs(target);
> +		if (err)
> +			goto out;
> +
>   		targets_arr[i] = target;
>   		targets->nr++;
>   	}
> @@ -608,9 +845,6 @@ static ssize_t operations_store(struct kobject *kobj,
>   
>   	for (id = 0; id < NR_DAMON_OPS; id++) {
>   		if (sysfs_streq(buf, damon_sysfs_ops_strs[id])) {
> -			/* Support only vaddr */
> -			if (id != DAMON_OPS_VADDR)
> -				return -EINVAL;
>   			context->ops_id = id;
>   			return count;
>   		}
> @@ -855,10 +1089,37 @@ static void damon_sysfs_destroy_targets(struct damon_ctx *ctx)
>   	}
>   }
>   
> +static int damon_sysfs_set_regions(struct damon_target *t,
> +		struct damon_sysfs_regions *sysfs_regions)
> +{
> +	int i;
> +
> +	for (i = 0; i < sysfs_regions->nr; i++) {
> +		struct damon_sysfs_region *sys_region =
> +			sysfs_regions->regions_arr[i];
> +		struct damon_region *prev, *r;
> +
> +		if (sys_region->start > sys_region->end)
> +			return -EINVAL;
> +		r = damon_new_region(sys_region->start, sys_region->end);
> +		if (!r)
> +			return -ENOMEM;
> +		damon_add_region(r, t);
> +		if (damon_nr_regions(t) > 1) {
> +			prev = damon_prev_region(r);
> +			if (prev->ar.end > r->ar.start) {
> +				damon_destroy_region(r, t);
> +				return -EINVAL;
> +			}
> +		}
> +	}
> +	return 0;
> +}
> +
>   static int damon_sysfs_set_targets(struct damon_ctx *ctx,
>   		struct damon_sysfs_targets *sysfs_targets)
>   {
> -	int i;
> +	int i, err;
>   
>   	for (i = 0; i < sysfs_targets->nr; i++) {
>   		struct damon_sysfs_target *sys_target =
> @@ -877,6 +1138,11 @@ static int damon_sysfs_set_targets(struct damon_ctx *ctx,
>   			}
>   		}
>   		damon_add_target(ctx, t);
> +		err = damon_sysfs_set_regions(t, sys_target->regions);
> +		if (err) {
> +			damon_sysfs_destroy_targets(ctx);
> +			return err;
> +		}
>   	}
>   	return 0;
>   }

-- 
Best Regards!
Xin Hao