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Message-ID: <CABmGT5GARdTGN+EgNvXHqR2tLD2X-BeNy5gAhTPVdi700+C2Og@mail.gmail.com>
Date: Mon, 15 May 2023 15:00:47 -0600
From: "T.J. Alumbaugh" <talumbau@...gle.com>
To: Yuanchu Xie <yuanchu@...gle.com>
Cc: David Hildenbrand <david@...hat.com>,
"Sudarshan Rajagopalan (QUIC)" <quic_sudaraja@...cinc.com>,
kai.huang@...el.com, hch@....de, jon@...anix.com,
SeongJae Park <sj@...nel.org>,
Shakeel Butt <shakeelb@...gle.com>,
Aneesh Kumar K V <aneesh.kumar@...ux.ibm.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Muchun Song <muchun.song@...ux.dev>,
Yu Zhao <yuzhao@...gle.com>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Yosry Ahmed <yosryahmed@...gle.com>,
Vasily Averin <vasily.averin@...ux.dev>,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
cgroups@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] virtio-balloon: Add Working Set reporting
For completeness, the corresponding QEMU device change is here:
https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg02503.html
and the proposed VIRTIO spec change is here:
https://lists.oasis-open.org/archives/virtio-comment/202305/msg00227.html
I think some of the more fundamental questions about the driver change
might be best handled on virtio-comment and/or virtio-dev. Thanks,
-T.J.
On Tue, May 9, 2023 at 12:54 PM Yuanchu Xie <yuanchu@...gle.com> wrote:
>
> From: talumbau <talumbau@...gle.com>
>
> - Add WS and notification vqueues
> - Add simple interface to kernel WS functions
> - Driver receives config info and sends reports on notification
> - use mutex to guard virtio_balloon state
>
> Signed-off-by: T.J. Alumbaugh <talumbau@...gle.com>
> Signed-off-by: Yuanchu Xie <yuanchu@...gle.com>
> ---
> drivers/virtio/virtio_balloon.c | 243 +++++++++++++++++++++++++++-
> include/linux/balloon_compaction.h | 6 +
> include/uapi/linux/virtio_balloon.h | 21 +++
> mm/vmscan.c | 102 ++++++++++++
> 4 files changed, 371 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 3f78a3a1eb75..edfa2a4960a3 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -11,6 +11,7 @@
> #include <linux/swap.h>
> #include <linux/workqueue.h>
> #include <linux/delay.h>
> +#include <linux/device.h>
> #include <linux/slab.h>
> #include <linux/module.h>
> #include <linux/balloon_compaction.h>
> @@ -39,12 +40,22 @@
> (1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT))
> #define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER)
>
> +/* TODO: replace with a registration interface, similar to shrinker registration. */
> +extern int register_wss_receiver(void *receiver, struct pglist_data *pgdat,
> + unsigned long *intervals, unsigned long nr_bins,
> + unsigned long report_threshold,
> + unsigned long refresh_threshold);
> +extern void unregister_wss_receiver(void *receiver);
> +extern bool working_set_request(struct pglist_data *pgdat);
> +
> enum virtio_balloon_vq {
> VIRTIO_BALLOON_VQ_INFLATE,
> VIRTIO_BALLOON_VQ_DEFLATE,
> VIRTIO_BALLOON_VQ_STATS,
> VIRTIO_BALLOON_VQ_FREE_PAGE,
> VIRTIO_BALLOON_VQ_REPORTING,
> + VIRTIO_BALLOON_VQ_WS,
> + VIRTIO_BALLOON_VQ_NOTIFY,
> VIRTIO_BALLOON_VQ_MAX
> };
>
> @@ -54,7 +65,8 @@ enum virtio_balloon_config_read {
>
> struct virtio_balloon {
> struct virtio_device *vdev;
> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq,
> + *ws_vq, *notification_vq;
>
> /* Balloon's own wq for cpu-intensive work items */
> struct workqueue_struct *balloon_wq;
> @@ -64,6 +76,8 @@ struct virtio_balloon {
> /* The balloon servicing is delegated to a freezable workqueue. */
> struct work_struct update_balloon_stats_work;
> struct work_struct update_balloon_size_work;
> + struct work_struct update_balloon_ws_work;
> + struct work_struct update_balloon_notification_work;
>
> /* Prevent updating balloon when it is being canceled. */
> spinlock_t stop_update_lock;
> @@ -110,6 +124,10 @@ struct virtio_balloon {
> /* Memory statistics */
> struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
>
> + /* A buffer to hold incoming notification from the host. */
> + unsigned int notification_size;
> + void *notification_buf;
> +
> /* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */
> struct shrinker shrinker;
>
> @@ -119,6 +137,10 @@ struct virtio_balloon {
> /* Free page reporting device */
> struct virtqueue *reporting_vq;
> struct page_reporting_dev_info pr_dev_info;
> +
> + /* Working Set reporting */
> + u32 ws_num_bins;
> + struct virtio_balloon_ws *ws;
> };
>
> static const struct virtio_device_id id_table[] = {
> @@ -301,6 +323,41 @@ static unsigned int leak_balloon(struct virtio_balloon *vb, size_t num)
> return num_freed_pages;
> }
>
> +/* Must hold the balloon_lock while calling this function. */
> +static inline void reset_working_set(struct virtio_balloon *vb)
> +{
> + int i;
> +
> + for (i = 0; i < vb->ws_num_bins; ++i) {
> + vb->ws[i].tag = cpu_to_virtio16(vb->vdev, 0);
> + vb->ws[i].node_id = cpu_to_virtio16(vb->vdev, -1);
> + vb->ws[i].idle_age_ms = cpu_to_virtio64(vb->vdev, 0);
> + vb->ws[i].memory_size_bytes[0] = cpu_to_virtio64(vb->vdev, -1);
> + vb->ws[i].memory_size_bytes[1] = cpu_to_virtio64(vb->vdev, -1);
> + }
> +}
> +
> +/* Must hold the balloon_lock while calling this function. */
> +static inline void update_working_set(struct virtio_balloon *vb, int idx,
> + u64 idle_age, u64 bytes_anon,
> + u64 bytes_file)
> +{
> + vb->ws[idx].tag = cpu_to_virtio16(vb->vdev, 0);
> + vb->ws[idx].node_id = cpu_to_virtio16(vb->vdev, -1);
> + vb->ws[idx].idle_age_ms = cpu_to_virtio64(vb->vdev, idle_age);
> + vb->ws[idx].memory_size_bytes[0] = cpu_to_virtio64(vb->vdev,
> + bytes_anon);
> + vb->ws[idx].memory_size_bytes[1] = cpu_to_virtio64(vb->vdev,
> + bytes_file);
> +}
> +
> +static bool working_set_is_init(struct virtio_balloon *vb)
> +{
> + if (vb->ws[0].idle_age_ms > 0)
> + return true;
> + return false;
> +}
> +
> static inline void update_stat(struct virtio_balloon *vb, int idx,
> u16 tag, u64 val)
> {
> @@ -386,6 +443,16 @@ static void stats_handle_request(struct virtio_balloon *vb)
> virtqueue_kick(vq);
> }
>
> +static void notification_receive(struct virtqueue *vq)
> +{
> + struct virtio_balloon *vb = vq->vdev->priv;
> +
> + spin_lock(&vb->stop_update_lock);
> + if (!vb->stop_update)
> + queue_work(system_freezable_wq, &vb->update_balloon_notification_work);
> + spin_unlock(&vb->stop_update_lock);
> +}
> +
> static inline s64 towards_target(struct virtio_balloon *vb)
> {
> s64 target;
> @@ -465,6 +532,130 @@ static void update_balloon_stats_func(struct work_struct *work)
> stats_handle_request(vb);
> }
>
> +static int virtio_balloon_register_wss_receiver(struct virtio_balloon *vb,
> + __virtio64 *intervals, unsigned long nr_bins, __virtio64 refresh_ms,
> + __virtio64 report_ms)
> +{
> + struct pglist_data *pgdat;
> + unsigned long *bin_intervals = NULL;
> + int i, err;
> +
> + if (intervals && nr_bins) {
> + /* TODO: keep values as 32-bits throughout. */
> + bin_intervals = kzalloc(sizeof(unsigned long) * (nr_bins-1),
> + GFP_KERNEL);
> + for (i = 0; i < nr_bins - 1; i++)
> + bin_intervals[i] = (unsigned long)intervals[i];
> + pgdat = NODE_DATA(NUMA_NO_NODE);
> + err = register_wss_receiver(vb, pgdat, &(bin_intervals[0]),
> + nr_bins, (unsigned long) refresh_ms,
> + (unsigned long) report_ms);
> + kfree(bin_intervals);
> + return err;
> + }
> + return -EINVAL;
> +}
> +
> +void working_set_notify(void *wss_receiver, struct wss_bin *bins)
> +{
> + u64 bytes_nr_file, bytes_nr_anon;
> + struct virtio_balloon *vb = wss_receiver;
> + int idx = 0;
> +
> + if (!mutex_trylock(&vb->balloon_lock))
> + return;
> + for (; idx < vb->ws_num_bins; idx++) {
> + bytes_nr_anon = (u64)(bins[idx].nr_pages[0]) * PAGE_SIZE;
> + bytes_nr_file = (u64)(bins[idx].nr_pages[1]) * PAGE_SIZE;
> + update_working_set(vb, idx, jiffies_to_msecs(bins[idx].idle_age),
> + bytes_nr_anon, bytes_nr_file);
> + }
> + mutex_unlock(&vb->balloon_lock);
> + /* Send the working set report to the device. */
> + spin_lock(&vb->stop_update_lock);
> + if (!vb->stop_update)
> + queue_work(system_freezable_wq, &vb->update_balloon_ws_work);
> + spin_unlock(&vb->stop_update_lock);
> +}
> +
> +EXPORT_SYMBOL(working_set_notify);
> +
> +static void update_balloon_notification_func(struct work_struct *work)
> +{
> + struct virtio_balloon *vb;
> + struct scatterlist sg_in;
> + struct pglist_data *pgdat;
> + __virtio64 *bin_intervals;
> + __virtio64 refresh_ms, report_ms;
> + int16_t tag;
> + char *buf;
> + int len;
> +
> + vb = container_of(work, struct virtio_balloon,
> + update_balloon_notification_work);
> +
> + /* Read a Working Set notification from the device. */
> + buf = (char *)vb->notification_buf;
> + tag = *((int16_t *)buf);
> + buf += sizeof(int16_t);
> + if (tag == VIRTIO_BALLOON_WS_REQUEST) {
> + pgdat = NODE_DATA(NUMA_NO_NODE);
> + working_set_request(pgdat);
> + } else if (tag == VIRTIO_BALLOON_WS_CONFIG) {
> + mutex_lock(&vb->balloon_lock);
> + reset_working_set(vb);
> + mutex_unlock(&vb->balloon_lock);
> + bin_intervals = (__virtio64 *) buf;
> + buf += sizeof(__virtio64) * (vb->ws_num_bins - 1);
> + refresh_ms = *((__virtio64 *) buf);
> + buf += sizeof(__virtio64);
> + report_ms = *((__virtio64 *) buf);
> + virtio_balloon_register_wss_receiver(vb, bin_intervals, vb->ws_num_bins,
> + refresh_ms, report_ms);
> + } else {
> + dev_warn(&vb->vdev->dev, "Received invalid notification, %u\n", tag);
> + return;
> + }
> +
> + /* Detach all the used buffers from the vq */
> + while (virtqueue_get_buf(vb->notification_vq, &len))
> + ;
> + /* Add a new notification buffer for device to fill. */
> + sg_init_one(&sg_in, vb->notification_buf, vb->notification_size);
> + virtqueue_add_inbuf(vb->notification_vq, &sg_in, 1, vb, GFP_KERNEL);
> + virtqueue_kick(vb->notification_vq);
> +}
> +
> +static void update_balloon_ws_func(struct work_struct *work)
> +{
> + struct virtio_balloon *vb;
> + struct scatterlist sg_out;
> + int err = 0;
> + int unused;
> +
> + vb = container_of(work, struct virtio_balloon,
> + update_balloon_ws_work);
> +
> + mutex_lock(&vb->balloon_lock);
> + if (working_set_is_init(vb)) {
> + /* Detach all the used buffers from the vq */
> + while (virtqueue_get_buf(vb->ws_vq, &unused))
> + ;
> + sg_init_one(&sg_out, vb->ws, sizeof(struct virtio_balloon_ws) * vb->ws_num_bins);
> + err = virtqueue_add_outbuf(vb->ws_vq, &sg_out, 1, vb, GFP_KERNEL);
> + } else {
> + dev_warn(&vb->vdev->dev, "Working Set not initialized.");
> + err = -EINVAL;
> + }
> + mutex_unlock(&vb->balloon_lock);
> + if (unlikely(err)) {
> + dev_err(&vb->vdev->dev,
> + "Failed to send working set report err = %d\n", err);
> + } else {
> + virtqueue_kick(vb->ws_vq);
> + }
> +}
> +
> static void update_balloon_size_func(struct work_struct *work)
> {
> struct virtio_balloon *vb;
> @@ -508,6 +699,10 @@ static int init_vqs(struct virtio_balloon *vb)
> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> names[VIRTIO_BALLOON_VQ_REPORTING] = NULL;
> + callbacks[VIRTIO_BALLOON_VQ_WS] = NULL;
> + names[VIRTIO_BALLOON_VQ_WS] = NULL;
> + callbacks[VIRTIO_BALLOON_VQ_NOTIFY] = NULL;
> + names[VIRTIO_BALLOON_VQ_NOTIFY] = NULL;
>
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
> names[VIRTIO_BALLOON_VQ_STATS] = "stats";
> @@ -524,6 +719,13 @@ static int init_vqs(struct virtio_balloon *vb)
> callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack;
> }
>
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_WS_REPORTING)) {
> + names[VIRTIO_BALLOON_VQ_WS] = "ws";
> + callbacks[VIRTIO_BALLOON_VQ_WS] = NULL;
> + names[VIRTIO_BALLOON_VQ_NOTIFY] = "notify";
> + callbacks[VIRTIO_BALLOON_VQ_NOTIFY] = notification_receive;
> + }
> +
> err = virtio_find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX, vqs,
> callbacks, names, NULL);
> if (err)
> @@ -534,6 +736,7 @@ static int init_vqs(struct virtio_balloon *vb)
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
> struct scatterlist sg;
> unsigned int num_stats;
> +
> vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];
>
> /*
> @@ -553,6 +756,23 @@ static int init_vqs(struct virtio_balloon *vb)
> virtqueue_kick(vb->stats_vq);
> }
>
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_WS_REPORTING)) {
> + struct scatterlist sg;
> +
> + vb->ws_vq = vqs[VIRTIO_BALLOON_VQ_WS];
> + vb->notification_vq = vqs[VIRTIO_BALLOON_VQ_NOTIFY];
> +
> + /* Prime the notification virtqueue for the device to fill.*/
> + sg_init_one(&sg, vb->notification_buf, vb->notification_size);
> + err = virtqueue_add_inbuf(vb->notification_vq, &sg, 1, vb, GFP_KERNEL);
> + if (unlikely(err)) {
> + dev_err(&vb->vdev->dev,
> + "Failed to prepare notifications, err = %d\n", err);
> + } else {
> + virtqueue_kick(vb->notification_vq);
> + }
> + }
> +
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
> vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];
>
> @@ -878,6 +1098,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
>
> INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
> INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
> + INIT_WORK(&vb->update_balloon_ws_work, update_balloon_ws_func);
> + INIT_WORK(&vb->update_balloon_notification_work, update_balloon_notification_func);
> spin_lock_init(&vb->stop_update_lock);
> mutex_init(&vb->balloon_lock);
> init_waitqueue_head(&vb->acked);
> @@ -885,6 +1107,20 @@ static int virtballoon_probe(struct virtio_device *vdev)
>
> balloon_devinfo_init(&vb->vb_dev_info);
>
> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_WS_REPORTING)) {
> + virtio_cread_le(vdev, struct virtio_balloon_config, ws_num_bins,
> + &vb->ws_num_bins);
> + /* Allocate space for a Working Set report. */
> + vb->ws = kcalloc(vb->ws_num_bins,
> + sizeof(struct virtio_balloon_ws), GFP_KERNEL);
> + /* Allocate space for host notifications. */
> + vb->notification_size =
> + sizeof(uint16_t) +
> + sizeof(uint64_t) * (vb->ws_num_bins + 1);
> + vb->notification_buf = kzalloc(vb->notification_size, GFP_KERNEL);
> + reset_working_set(vb);
> + }
> +
> err = init_vqs(vb);
> if (err)
> goto out_free_vb;
> @@ -1034,11 +1270,15 @@ static void virtballoon_remove(struct virtio_device *vdev)
> unregister_oom_notifier(&vb->oom_nb);
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
> virtio_balloon_unregister_shrinker(vb);
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_WS_REPORTING))
> + unregister_wss_receiver(vb);
> spin_lock_irq(&vb->stop_update_lock);
> vb->stop_update = true;
> spin_unlock_irq(&vb->stop_update_lock);
> cancel_work_sync(&vb->update_balloon_size_work);
> cancel_work_sync(&vb->update_balloon_stats_work);
> + cancel_work_sync(&vb->update_balloon_ws_work);
> + cancel_work_sync(&vb->update_balloon_notification_work);
>
> if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
> cancel_work_sync(&vb->report_free_page_work);
> @@ -1104,6 +1344,7 @@ static unsigned int features[] = {
> VIRTIO_BALLOON_F_FREE_PAGE_HINT,
> VIRTIO_BALLOON_F_PAGE_POISON,
> VIRTIO_BALLOON_F_REPORTING,
> + VIRTIO_BALLOON_F_WS_REPORTING,
> };
>
> static struct virtio_driver virtio_balloon_driver = {
> diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
> index 5ca2d5699620..2cf4fca6e7f1 100644
> --- a/include/linux/balloon_compaction.h
> +++ b/include/linux/balloon_compaction.h
> @@ -43,6 +43,7 @@
> #include <linux/err.h>
> #include <linux/fs.h>
> #include <linux/list.h>
> +#include <linux/mmzone.h>
>
> /*
> * Balloon device information descriptor.
> @@ -67,6 +68,11 @@ extern size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
> struct list_head *pages);
> extern size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
> struct list_head *pages, size_t n_req_pages);
> +/*
> + * Function to send the working set to a receiver (e.g. the balloon driver)
> + * TODO: Replace with a proper registration interface, similar to shrinkers.
> + */
> +extern void working_set_notify(void *wss_receiver, struct wss_bin *bins);
>
> static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
> {
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index ddaa45e723c4..06d0683d8d8c 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -37,6 +37,7 @@
> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */
> #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */
> #define VIRTIO_BALLOON_F_REPORTING 5 /* Page reporting virtqueue */
> +#define VIRTIO_BALLOON_F_WS_REPORTING 6 /* Working Set Size reporting */
>
> /* Size of a PFN in the balloon interface. */
> #define VIRTIO_BALLOON_PFN_SHIFT 12
> @@ -59,6 +60,8 @@ struct virtio_balloon_config {
> };
> /* Stores PAGE_POISON if page poisoning is in use */
> __le32 poison_val;
> + /* Number of bins for Working Set report if in use. */
> + __le32 ws_num_bins;
> };
>
> #define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
> @@ -116,4 +119,22 @@ struct virtio_balloon_stat {
> __virtio64 val;
> } __attribute__((packed));
>
> +enum virtio_balloon_ws_op {
> + VIRTIO_BALLOON_WS_REQUEST = 1,
> + VIRTIO_BALLOON_WS_CONFIG = 2,
> +};
> +
> +struct virtio_balloon_ws {
> +#define VIRTIO_BALLOON_WS_RECLAIMABLE 0
> +#define VIRTIO_BALLOON_WS_DISCARDABLE 1
> + /* TODO: Provide additional detail on memory, e.g. reclaimable. */
> + __virtio16 tag;
> + /* TODO: Support per-NUMA node reports. */
> + __virtio16 node_id;
> + uint8_t reserved[4];
> + __virtio64 idle_age_ms;
> + /* Track separately for ANON_AND_FILE. */
> + __virtio64 memory_size_bytes[2];
> +};
> +
> #endif /* _LINUX_VIRTIO_BALLOON_H */
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b3adf924691c..ab343974de91 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -209,6 +209,8 @@ static void set_task_reclaim_state(struct task_struct *task,
> LIST_HEAD(shrinker_list);
> DECLARE_RWSEM(shrinker_rwsem);
>
> +static void *wss_receiver;
> +
> #ifdef CONFIG_MEMCG
> static int shrinker_nr_max;
>
> @@ -621,6 +623,54 @@ static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
> return size;
> }
>
> +/*
> + * Register/unregister a receiver of wss notifications
> + * TODO: Replace with a proper registration interface, similar to shrinkers.
> + */
> +int register_wss_receiver(void *receiver, struct pglist_data *pgdat,
> + unsigned long *intervals, unsigned long nr_bins,
> + unsigned long refresh_threshold,
> + unsigned long report_threshold)
> +{
> + struct wss *wss;
> + struct wss_bin *bins;
> + int i;
> +
> + wss_receiver = receiver;
> +
> + if (!pgdat)
> + return 0;
> +
> + if (!intervals || !nr_bins)
> + return 0;
> +
> + bins = kzalloc(sizeof(wss->bins), GFP_KERNEL);
> + if (!bins)
> + return -ENOMEM;
> +
> + for (i = 0; i < nr_bins - 1; i++) {
> + bins[i].idle_age = msecs_to_jiffies(*intervals);
> + intervals++;
> + }
> + bins[i].idle_age = -1;
> +
> + wss = lruvec_wss(mem_cgroup_lruvec(NULL, pgdat));
> +
> + mutex_lock(&wss->bins_lock);
> + memcpy(wss->bins, bins, sizeof(wss->bins));
> + WRITE_ONCE(wss->refresh_threshold, msecs_to_jiffies(refresh_threshold));
> + WRITE_ONCE(wss->report_threshold, msecs_to_jiffies(report_threshold));
> + mutex_unlock(&wss->bins_lock);
> + return 0;
> +}
> +EXPORT_SYMBOL(register_wss_receiver);
> +
> +void unregister_wss_receiver(void *receiver)
> +{
> + wss_receiver = NULL;
> +}
> +EXPORT_SYMBOL(unregister_wss_receiver);
> +
> /*
> * Add a shrinker callback to be called from the vm.
> */
> @@ -4606,6 +4656,12 @@ void report_wss(struct pglist_data *pgdat, struct scan_control *sc)
> refresh_wss(wss, memcg, pgdat, sc, 0);
> WRITE_ONCE(wss->timestamp, jiffies);
>
> + /* balloon driver subscribes to global memory reclaim */
> + if (!cgroup_reclaim(sc) && wss_receiver) {
> + pr_warn("Working Set Notify!");
> + working_set_notify(wss_receiver, wss->bins);
> + }
> +
> mutex_unlock(&wss->bins_lock);
>
> if (wss->notifier)
> @@ -4711,6 +4767,52 @@ void report_reaccess(struct lruvec *lruvec, struct lru_gen_mm_walk *walk)
> }
> }
>
> +/* TODO: Replace with a proper registration interface, similar to shrinkers. */
> +bool working_set_request(struct pglist_data *pgdat)
> +{
> + unsigned int flags;
> + struct scan_control sc = {
> + .may_writepage = true,
> + .may_unmap = true,
> + .may_swap = true,
> + .reclaim_idx = MAX_NR_ZONES - 1,
> + .gfp_mask = GFP_KERNEL,
> + };
> + struct wss *wss;
> +
> + if (!wss_receiver)
> + return false;
> +
> + wss = lruvec_wss(mem_cgroup_lruvec(NULL, pgdat));
> +
> + if (!mutex_trylock(&wss->bins_lock))
> + return false;
> +
> + if (wss->bins->idle_age != -1) {
> + unsigned long timestamp = READ_ONCE(wss->timestamp);
> + unsigned long threshold = READ_ONCE(wss->refresh_threshold);
> +
> + if (time_is_before_jiffies(timestamp + threshold)) {
> + // We might need to refresh the report.
> + set_task_reclaim_state(current, &sc.reclaim_state);
> + flags = memalloc_noreclaim_save();
> + refresh_wss(wss, NULL, pgdat, &sc, threshold);
> + memalloc_noreclaim_restore(flags);
> + set_task_reclaim_state(current, NULL);
> + }
> + }
> +
> + if (wss_receiver) {
> + pr_warn("WS notify inside ws request\n");
> + working_set_notify(wss_receiver, wss->bins);
> + }
> +
> + mutex_unlock(&wss->bins_lock);
> + return true;
> +
> +}
> +EXPORT_SYMBOL(working_set_request);
> +
> static struct pglist_data *kobj_to_pgdat(struct kobject *kobj)
> {
> int nid = IS_ENABLED(CONFIG_NUMA) ? kobj_to_dev(kobj)->id :
> --
> 2.40.1.521.gf1e218fcd8-goog
>
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