Version:  2.0.40 2.2.26 2.4.37 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Linux/drivers/virtio/virtio_balloon.c

  1 /*
  2  * Virtio balloon implementation, inspired by Dor Laor and Marcelo
  3  * Tosatti's implementations.
  4  *
  5  *  Copyright 2008 Rusty Russell IBM Corporation
  6  *
  7  *  This program is free software; you can redistribute it and/or modify
  8  *  it under the terms of the GNU General Public License as published by
  9  *  the Free Software Foundation; either version 2 of the License, or
 10  *  (at your option) any later version.
 11  *
 12  *  This program is distributed in the hope that it will be useful,
 13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15  *  GNU General Public License for more details.
 16  *
 17  *  You should have received a copy of the GNU General Public License
 18  *  along with this program; if not, write to the Free Software
 19  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 20  */
 21 
 22 #include <linux/virtio.h>
 23 #include <linux/virtio_balloon.h>
 24 #include <linux/swap.h>
 25 #include <linux/workqueue.h>
 26 #include <linux/delay.h>
 27 #include <linux/slab.h>
 28 #include <linux/module.h>
 29 #include <linux/balloon_compaction.h>
 30 #include <linux/oom.h>
 31 #include <linux/wait.h>
 32 #include <linux/mm.h>
 33 #include <linux/mount.h>
 34 
 35 /*
 36  * Balloon device works in 4K page units.  So each page is pointed to by
 37  * multiple balloon pages.  All memory counters in this driver are in balloon
 38  * page units.
 39  */
 40 #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
 41 #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
 42 #define OOM_VBALLOON_DEFAULT_PAGES 256
 43 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
 44 
 45 static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
 46 module_param(oom_pages, int, S_IRUSR | S_IWUSR);
 47 MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
 48 
 49 #ifdef CONFIG_BALLOON_COMPACTION
 50 static struct vfsmount *balloon_mnt;
 51 #endif
 52 
 53 struct virtio_balloon {
 54         struct virtio_device *vdev;
 55         struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
 56 
 57         /* The balloon servicing is delegated to a freezable workqueue. */
 58         struct work_struct update_balloon_stats_work;
 59         struct work_struct update_balloon_size_work;
 60 
 61         /* Prevent updating balloon when it is being canceled. */
 62         spinlock_t stop_update_lock;
 63         bool stop_update;
 64 
 65         /* Waiting for host to ack the pages we released. */
 66         wait_queue_head_t acked;
 67 
 68         /* Number of balloon pages we've told the Host we're not using. */
 69         unsigned int num_pages;
 70         /*
 71          * The pages we've told the Host we're not using are enqueued
 72          * at vb_dev_info->pages list.
 73          * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
 74          * to num_pages above.
 75          */
 76         struct balloon_dev_info vb_dev_info;
 77 
 78         /* Synchronize access/update to this struct virtio_balloon elements */
 79         struct mutex balloon_lock;
 80 
 81         /* The array of pfns we tell the Host about. */
 82         unsigned int num_pfns;
 83         __virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
 84 
 85         /* Memory statistics */
 86         struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
 87 
 88         /* To register callback in oom notifier call chain */
 89         struct notifier_block nb;
 90 };
 91 
 92 static struct virtio_device_id id_table[] = {
 93         { VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
 94         { 0 },
 95 };
 96 
 97 static u32 page_to_balloon_pfn(struct page *page)
 98 {
 99         unsigned long pfn = page_to_pfn(page);
100 
101         BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
102         /* Convert pfn from Linux page size to balloon page size. */
103         return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
104 }
105 
106 static struct page *balloon_pfn_to_page(u32 pfn)
107 {
108         BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
109         return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
110 }
111 
112 static void balloon_ack(struct virtqueue *vq)
113 {
114         struct virtio_balloon *vb = vq->vdev->priv;
115 
116         wake_up(&vb->acked);
117 }
118 
119 static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
120 {
121         struct scatterlist sg;
122         unsigned int len;
123 
124         sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
125 
126         /* We should always be able to add one buffer to an empty queue. */
127         virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
128         virtqueue_kick(vq);
129 
130         /* When host has read buffer, this completes via balloon_ack */
131         wait_event(vb->acked, virtqueue_get_buf(vq, &len));
132 
133 }
134 
135 static void set_page_pfns(struct virtio_balloon *vb,
136                           __virtio32 pfns[], struct page *page)
137 {
138         unsigned int i;
139 
140         /* Set balloon pfns pointing at this page.
141          * Note that the first pfn points at start of the page. */
142         for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
143                 pfns[i] = cpu_to_virtio32(vb->vdev,
144                                           page_to_balloon_pfn(page) + i);
145 }
146 
147 static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
148 {
149         struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
150         unsigned num_allocated_pages;
151 
152         /* We can only do one array worth at a time. */
153         num = min(num, ARRAY_SIZE(vb->pfns));
154 
155         mutex_lock(&vb->balloon_lock);
156         for (vb->num_pfns = 0; vb->num_pfns < num;
157              vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
158                 struct page *page = balloon_page_enqueue(vb_dev_info);
159 
160                 if (!page) {
161                         dev_info_ratelimited(&vb->vdev->dev,
162                                              "Out of puff! Can't get %u pages\n",
163                                              VIRTIO_BALLOON_PAGES_PER_PAGE);
164                         /* Sleep for at least 1/5 of a second before retry. */
165                         msleep(200);
166                         break;
167                 }
168                 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
169                 vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
170                 if (!virtio_has_feature(vb->vdev,
171                                         VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
172                         adjust_managed_page_count(page, -1);
173         }
174 
175         num_allocated_pages = vb->num_pfns;
176         /* Did we get any? */
177         if (vb->num_pfns != 0)
178                 tell_host(vb, vb->inflate_vq);
179         mutex_unlock(&vb->balloon_lock);
180 
181         return num_allocated_pages;
182 }
183 
184 static void release_pages_balloon(struct virtio_balloon *vb)
185 {
186         unsigned int i;
187         struct page *page;
188 
189         /* Find pfns pointing at start of each page, get pages and free them. */
190         for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
191                 page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev,
192                                                            vb->pfns[i]));
193                 if (!virtio_has_feature(vb->vdev,
194                                         VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
195                         adjust_managed_page_count(page, 1);
196                 put_page(page); /* balloon reference */
197         }
198 }
199 
200 static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
201 {
202         unsigned num_freed_pages;
203         struct page *page;
204         struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
205 
206         /* We can only do one array worth at a time. */
207         num = min(num, ARRAY_SIZE(vb->pfns));
208 
209         mutex_lock(&vb->balloon_lock);
210         /* We can't release more pages than taken */
211         num = min(num, (size_t)vb->num_pages);
212         for (vb->num_pfns = 0; vb->num_pfns < num;
213              vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
214                 page = balloon_page_dequeue(vb_dev_info);
215                 if (!page)
216                         break;
217                 set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
218                 vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
219         }
220 
221         num_freed_pages = vb->num_pfns;
222         /*
223          * Note that if
224          * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
225          * is true, we *have* to do it in this order
226          */
227         if (vb->num_pfns != 0)
228                 tell_host(vb, vb->deflate_vq);
229         release_pages_balloon(vb);
230         mutex_unlock(&vb->balloon_lock);
231         return num_freed_pages;
232 }
233 
234 static inline void update_stat(struct virtio_balloon *vb, int idx,
235                                u16 tag, u64 val)
236 {
237         BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
238         vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag);
239         vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val);
240 }
241 
242 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
243 
244 static void update_balloon_stats(struct virtio_balloon *vb)
245 {
246         unsigned long events[NR_VM_EVENT_ITEMS];
247         struct sysinfo i;
248         int idx = 0;
249         long available;
250 
251         all_vm_events(events);
252         si_meminfo(&i);
253 
254         available = si_mem_available();
255 
256         update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
257                                 pages_to_bytes(events[PSWPIN]));
258         update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
259                                 pages_to_bytes(events[PSWPOUT]));
260         update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
261         update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
262         update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
263                                 pages_to_bytes(i.freeram));
264         update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
265                                 pages_to_bytes(i.totalram));
266         update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
267                                 pages_to_bytes(available));
268 }
269 
270 /*
271  * While most virtqueues communicate guest-initiated requests to the hypervisor,
272  * the stats queue operates in reverse.  The driver initializes the virtqueue
273  * with a single buffer.  From that point forward, all conversations consist of
274  * a hypervisor request (a call to this function) which directs us to refill
275  * the virtqueue with a fresh stats buffer.  Since stats collection can sleep,
276  * we delegate the job to a freezable workqueue that will do the actual work via
277  * stats_handle_request().
278  */
279 static void stats_request(struct virtqueue *vq)
280 {
281         struct virtio_balloon *vb = vq->vdev->priv;
282 
283         spin_lock(&vb->stop_update_lock);
284         if (!vb->stop_update)
285                 queue_work(system_freezable_wq, &vb->update_balloon_stats_work);
286         spin_unlock(&vb->stop_update_lock);
287 }
288 
289 static void stats_handle_request(struct virtio_balloon *vb)
290 {
291         struct virtqueue *vq;
292         struct scatterlist sg;
293         unsigned int len;
294 
295         update_balloon_stats(vb);
296 
297         vq = vb->stats_vq;
298         if (!virtqueue_get_buf(vq, &len))
299                 return;
300         sg_init_one(&sg, vb->stats, sizeof(vb->stats));
301         virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
302         virtqueue_kick(vq);
303 }
304 
305 static void virtballoon_changed(struct virtio_device *vdev)
306 {
307         struct virtio_balloon *vb = vdev->priv;
308         unsigned long flags;
309 
310         spin_lock_irqsave(&vb->stop_update_lock, flags);
311         if (!vb->stop_update)
312                 queue_work(system_freezable_wq, &vb->update_balloon_size_work);
313         spin_unlock_irqrestore(&vb->stop_update_lock, flags);
314 }
315 
316 static inline s64 towards_target(struct virtio_balloon *vb)
317 {
318         s64 target;
319         u32 num_pages;
320 
321         virtio_cread(vb->vdev, struct virtio_balloon_config, num_pages,
322                      &num_pages);
323 
324         /* Legacy balloon config space is LE, unlike all other devices. */
325         if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
326                 num_pages = le32_to_cpu((__force __le32)num_pages);
327 
328         target = num_pages;
329         return target - vb->num_pages;
330 }
331 
332 static void update_balloon_size(struct virtio_balloon *vb)
333 {
334         u32 actual = vb->num_pages;
335 
336         /* Legacy balloon config space is LE, unlike all other devices. */
337         if (!virtio_has_feature(vb->vdev, VIRTIO_F_VERSION_1))
338                 actual = (__force u32)cpu_to_le32(actual);
339 
340         virtio_cwrite(vb->vdev, struct virtio_balloon_config, actual,
341                       &actual);
342 }
343 
344 /*
345  * virtballoon_oom_notify - release pages when system is under severe
346  *                          memory pressure (called from out_of_memory())
347  * @self : notifier block struct
348  * @dummy: not used
349  * @parm : returned - number of freed pages
350  *
351  * The balancing of memory by use of the virtio balloon should not cause
352  * the termination of processes while there are pages in the balloon.
353  * If virtio balloon manages to release some memory, it will make the
354  * system return and retry the allocation that forced the OOM killer
355  * to run.
356  */
357 static int virtballoon_oom_notify(struct notifier_block *self,
358                                   unsigned long dummy, void *parm)
359 {
360         struct virtio_balloon *vb;
361         unsigned long *freed;
362         unsigned num_freed_pages;
363 
364         vb = container_of(self, struct virtio_balloon, nb);
365         if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
366                 return NOTIFY_OK;
367 
368         freed = parm;
369         num_freed_pages = leak_balloon(vb, oom_pages);
370         update_balloon_size(vb);
371         *freed += num_freed_pages;
372 
373         return NOTIFY_OK;
374 }
375 
376 static void update_balloon_stats_func(struct work_struct *work)
377 {
378         struct virtio_balloon *vb;
379 
380         vb = container_of(work, struct virtio_balloon,
381                           update_balloon_stats_work);
382         stats_handle_request(vb);
383 }
384 
385 static void update_balloon_size_func(struct work_struct *work)
386 {
387         struct virtio_balloon *vb;
388         s64 diff;
389 
390         vb = container_of(work, struct virtio_balloon,
391                           update_balloon_size_work);
392         diff = towards_target(vb);
393 
394         if (diff > 0)
395                 diff -= fill_balloon(vb, diff);
396         else if (diff < 0)
397                 diff += leak_balloon(vb, -diff);
398         update_balloon_size(vb);
399 
400         if (diff)
401                 queue_work(system_freezable_wq, work);
402 }
403 
404 static int init_vqs(struct virtio_balloon *vb)
405 {
406         struct virtqueue *vqs[3];
407         vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
408         static const char * const names[] = { "inflate", "deflate", "stats" };
409         int err, nvqs;
410 
411         /*
412          * We expect two virtqueues: inflate and deflate, and
413          * optionally stat.
414          */
415         nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
416         err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
417         if (err)
418                 return err;
419 
420         vb->inflate_vq = vqs[0];
421         vb->deflate_vq = vqs[1];
422         if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
423                 struct scatterlist sg;
424                 vb->stats_vq = vqs[2];
425 
426                 /*
427                  * Prime this virtqueue with one buffer so the hypervisor can
428                  * use it to signal us later (it can't be broken yet!).
429                  */
430                 sg_init_one(&sg, vb->stats, sizeof vb->stats);
431                 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
432                     < 0)
433                         BUG();
434                 virtqueue_kick(vb->stats_vq);
435         }
436         return 0;
437 }
438 
439 #ifdef CONFIG_BALLOON_COMPACTION
440 /*
441  * virtballoon_migratepage - perform the balloon page migration on behalf of
442  *                           a compation thread.     (called under page lock)
443  * @vb_dev_info: the balloon device
444  * @newpage: page that will replace the isolated page after migration finishes.
445  * @page   : the isolated (old) page that is about to be migrated to newpage.
446  * @mode   : compaction mode -- not used for balloon page migration.
447  *
448  * After a ballooned page gets isolated by compaction procedures, this is the
449  * function that performs the page migration on behalf of a compaction thread
450  * The page migration for virtio balloon is done in a simple swap fashion which
451  * follows these two macro steps:
452  *  1) insert newpage into vb->pages list and update the host about it;
453  *  2) update the host about the old page removed from vb->pages list;
454  *
455  * This function preforms the balloon page migration task.
456  * Called through balloon_mapping->a_ops->migratepage
457  */
458 static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
459                 struct page *newpage, struct page *page, enum migrate_mode mode)
460 {
461         struct virtio_balloon *vb = container_of(vb_dev_info,
462                         struct virtio_balloon, vb_dev_info);
463         unsigned long flags;
464 
465         /*
466          * In order to avoid lock contention while migrating pages concurrently
467          * to leak_balloon() or fill_balloon() we just give up the balloon_lock
468          * this turn, as it is easier to retry the page migration later.
469          * This also prevents fill_balloon() getting stuck into a mutex
470          * recursion in the case it ends up triggering memory compaction
471          * while it is attempting to inflate the ballon.
472          */
473         if (!mutex_trylock(&vb->balloon_lock))
474                 return -EAGAIN;
475 
476         get_page(newpage); /* balloon reference */
477 
478         /* balloon's page migration 1st step  -- inflate "newpage" */
479         spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
480         balloon_page_insert(vb_dev_info, newpage);
481         vb_dev_info->isolated_pages--;
482         __count_vm_event(BALLOON_MIGRATE);
483         spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
484         vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
485         set_page_pfns(vb, vb->pfns, newpage);
486         tell_host(vb, vb->inflate_vq);
487 
488         /* balloon's page migration 2nd step -- deflate "page" */
489         balloon_page_delete(page);
490         vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
491         set_page_pfns(vb, vb->pfns, page);
492         tell_host(vb, vb->deflate_vq);
493 
494         mutex_unlock(&vb->balloon_lock);
495 
496         put_page(page); /* balloon reference */
497 
498         return MIGRATEPAGE_SUCCESS;
499 }
500 
501 static struct dentry *balloon_mount(struct file_system_type *fs_type,
502                 int flags, const char *dev_name, void *data)
503 {
504         static const struct dentry_operations ops = {
505                 .d_dname = simple_dname,
506         };
507 
508         return mount_pseudo(fs_type, "balloon-kvm:", NULL, &ops,
509                                 BALLOON_KVM_MAGIC);
510 }
511 
512 static struct file_system_type balloon_fs = {
513         .name           = "balloon-kvm",
514         .mount          = balloon_mount,
515         .kill_sb        = kill_anon_super,
516 };
517 
518 #endif /* CONFIG_BALLOON_COMPACTION */
519 
520 static int virtballoon_probe(struct virtio_device *vdev)
521 {
522         struct virtio_balloon *vb;
523         int err;
524 
525         if (!vdev->config->get) {
526                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
527                         __func__);
528                 return -EINVAL;
529         }
530 
531         vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
532         if (!vb) {
533                 err = -ENOMEM;
534                 goto out;
535         }
536 
537         INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
538         INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
539         spin_lock_init(&vb->stop_update_lock);
540         vb->stop_update = false;
541         vb->num_pages = 0;
542         mutex_init(&vb->balloon_lock);
543         init_waitqueue_head(&vb->acked);
544         vb->vdev = vdev;
545 
546         balloon_devinfo_init(&vb->vb_dev_info);
547 
548         err = init_vqs(vb);
549         if (err)
550                 goto out_free_vb;
551 
552         vb->nb.notifier_call = virtballoon_oom_notify;
553         vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
554         err = register_oom_notifier(&vb->nb);
555         if (err < 0)
556                 goto out_del_vqs;
557 
558 #ifdef CONFIG_BALLOON_COMPACTION
559         balloon_mnt = kern_mount(&balloon_fs);
560         if (IS_ERR(balloon_mnt)) {
561                 err = PTR_ERR(balloon_mnt);
562                 unregister_oom_notifier(&vb->nb);
563                 goto out_del_vqs;
564         }
565 
566         vb->vb_dev_info.migratepage = virtballoon_migratepage;
567         vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
568         if (IS_ERR(vb->vb_dev_info.inode)) {
569                 err = PTR_ERR(vb->vb_dev_info.inode);
570                 kern_unmount(balloon_mnt);
571                 unregister_oom_notifier(&vb->nb);
572                 vb->vb_dev_info.inode = NULL;
573                 goto out_del_vqs;
574         }
575         vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
576 #endif
577 
578         virtio_device_ready(vdev);
579 
580         return 0;
581 
582 out_del_vqs:
583         vdev->config->del_vqs(vdev);
584 out_free_vb:
585         kfree(vb);
586 out:
587         return err;
588 }
589 
590 static void remove_common(struct virtio_balloon *vb)
591 {
592         /* There might be pages left in the balloon: free them. */
593         while (vb->num_pages)
594                 leak_balloon(vb, vb->num_pages);
595         update_balloon_size(vb);
596 
597         /* Now we reset the device so we can clean up the queues. */
598         vb->vdev->config->reset(vb->vdev);
599 
600         vb->vdev->config->del_vqs(vb->vdev);
601 }
602 
603 static void virtballoon_remove(struct virtio_device *vdev)
604 {
605         struct virtio_balloon *vb = vdev->priv;
606 
607         unregister_oom_notifier(&vb->nb);
608 
609         spin_lock_irq(&vb->stop_update_lock);
610         vb->stop_update = true;
611         spin_unlock_irq(&vb->stop_update_lock);
612         cancel_work_sync(&vb->update_balloon_size_work);
613         cancel_work_sync(&vb->update_balloon_stats_work);
614 
615         remove_common(vb);
616         if (vb->vb_dev_info.inode)
617                 iput(vb->vb_dev_info.inode);
618         kfree(vb);
619 }
620 
621 #ifdef CONFIG_PM_SLEEP
622 static int virtballoon_freeze(struct virtio_device *vdev)
623 {
624         struct virtio_balloon *vb = vdev->priv;
625 
626         /*
627          * The workqueue is already frozen by the PM core before this
628          * function is called.
629          */
630         remove_common(vb);
631         return 0;
632 }
633 
634 static int virtballoon_restore(struct virtio_device *vdev)
635 {
636         struct virtio_balloon *vb = vdev->priv;
637         int ret;
638 
639         ret = init_vqs(vdev->priv);
640         if (ret)
641                 return ret;
642 
643         virtio_device_ready(vdev);
644 
645         if (towards_target(vb))
646                 virtballoon_changed(vdev);
647         update_balloon_size(vb);
648         return 0;
649 }
650 #endif
651 
652 static unsigned int features[] = {
653         VIRTIO_BALLOON_F_MUST_TELL_HOST,
654         VIRTIO_BALLOON_F_STATS_VQ,
655         VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
656 };
657 
658 static struct virtio_driver virtio_balloon_driver = {
659         .feature_table = features,
660         .feature_table_size = ARRAY_SIZE(features),
661         .driver.name =  KBUILD_MODNAME,
662         .driver.owner = THIS_MODULE,
663         .id_table =     id_table,
664         .probe =        virtballoon_probe,
665         .remove =       virtballoon_remove,
666         .config_changed = virtballoon_changed,
667 #ifdef CONFIG_PM_SLEEP
668         .freeze =       virtballoon_freeze,
669         .restore =      virtballoon_restore,
670 #endif
671 };
672 
673 module_virtio_driver(virtio_balloon_driver);
674 MODULE_DEVICE_TABLE(virtio, id_table);
675 MODULE_DESCRIPTION("Virtio balloon driver");
676 MODULE_LICENSE("GPL");
677 

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