A balloon enhancement, and a minor race-on-module-unload theoretical
bug which doesn't merit cc: stable. All the exciting stuff went via MST this cycle. Thanks, Rusty. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJUkPhtAAoJENkgDmzRrbjxnEoP/iXZ2d0pwbSQSSw12wXec7BO aT698KzTHg2naRqWEhRbE5ujGW9ZR1hbkH3r70R2BlM5wZTwCAEkJB4SRfIu6u0R fv9GUgZTdSIlN2+yBW1eYHa2QlB8V/jx3P2Vyw3/ejGQ2vC6B7JbNsdCZJoyuH5A jZojZUrltfEdPVO4JkZ9sSzo64fzyoHGj8YYilH8ygcyZOshAvKvP/gOsFyRzyaj OPCU1CImBj5i1w2dFSErhKPJp/WQl7La1dKwTVE4lEGKadKDmqnStV0JKuvcRPv6 XB/9vwdRXtFIxRUKDH8Wj7DrkKRCsBh6DJUl+MC+c2TVLNu6v0D/WGOlmio2rvoZ 6CGwNBQg4Ex/J8CkcYsgISn/jzDS+0oaZK0P+IYNJtv5e7D6jPJcDoZ1yPXh1uPn 9ZYZlKa08o5/991f3HM2kJKWDP/OdzgHQH6w2exY01Zsz/6TATLvU7xoPQuHelWe mRd1kbW4ONIUAzIGPhd5PvtnmJ2L82+tN3VmYu50XAl2oSF8fzvQ/VHl9hgyu/vI WREA7/40e2DYkhRbu7focdEAFYo0HnuRq6Kwp5zYjbfgyBsiaY7DVvAUlnhwhMES kSFKejGUP00gofrXdffTYNu5LdKMN8eaVT7pMyxNXlQHSzXe3Vc6oqnpXzP17ii7 ahqmeDZKNUF3GSOHc4IC =COY0 -----END PGP SIGNATURE----- Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull virtio updates from Rusty Russell: "A balloon enhancement, and a minor race-on-module-unload theoretical bug which doesn't merit cc: stable. All the exciting stuff went via MST this cycle" * tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: virtio_balloon: free some memory from balloon on OOM virtio_balloon: return the amount of freed memory from leak_balloon() virtio_blk: fix race at module removal virtio: Fix comment typo 'CONFIG_S_FAILED'
This commit is contained in:
Linus Torvalds
commit
9f3e151299
3 changed files with 58 additions and 2 deletions
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@ -28,6 +28,7 @@
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/balloon_compaction.h>
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#include <linux/oom.h>
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/*
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* Balloon device works in 4K page units. So each page is pointed to by
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@ -36,6 +37,12 @@
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*/
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#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
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#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
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#define OOM_VBALLOON_DEFAULT_PAGES 256
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#define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80
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static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
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module_param(oom_pages, int, S_IRUSR | S_IWUSR);
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MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
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struct virtio_balloon
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{
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@ -71,6 +78,9 @@ struct virtio_balloon
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/* Memory statistics */
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int need_stats_update;
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struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
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/* To register callback in oom notifier call chain */
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struct notifier_block nb;
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};
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static struct virtio_device_id id_table[] = {
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@ -168,8 +178,9 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
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}
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}
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static void leak_balloon(struct virtio_balloon *vb, size_t num)
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static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
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{
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unsigned num_freed_pages;
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struct page *page;
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struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
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@ -186,6 +197,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
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vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
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}
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num_freed_pages = vb->num_pfns;
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/*
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* Note that if
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* virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
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@ -195,6 +207,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num)
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tell_host(vb, vb->deflate_vq);
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mutex_unlock(&vb->balloon_lock);
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release_pages_by_pfn(vb->pfns, vb->num_pfns);
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return num_freed_pages;
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}
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static inline void update_stat(struct virtio_balloon *vb, int idx,
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@ -287,6 +300,38 @@ static void update_balloon_size(struct virtio_balloon *vb)
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&actual);
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}
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/*
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* virtballoon_oom_notify - release pages when system is under severe
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* memory pressure (called from out_of_memory())
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* @self : notifier block struct
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* @dummy: not used
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* @parm : returned - number of freed pages
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*
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* The balancing of memory by use of the virtio balloon should not cause
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* the termination of processes while there are pages in the balloon.
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* If virtio balloon manages to release some memory, it will make the
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* system return and retry the allocation that forced the OOM killer
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* to run.
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*/
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static int virtballoon_oom_notify(struct notifier_block *self,
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unsigned long dummy, void *parm)
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{
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struct virtio_balloon *vb;
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unsigned long *freed;
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unsigned num_freed_pages;
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vb = container_of(self, struct virtio_balloon, nb);
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if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
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return NOTIFY_OK;
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freed = parm;
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num_freed_pages = leak_balloon(vb, oom_pages);
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update_balloon_size(vb);
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*freed += num_freed_pages;
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return NOTIFY_OK;
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}
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static int balloon(void *_vballoon)
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{
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struct virtio_balloon *vb = _vballoon;
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@ -443,6 +488,12 @@ static int virtballoon_probe(struct virtio_device *vdev)
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if (err)
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goto out_free_vb;
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vb->nb.notifier_call = virtballoon_oom_notify;
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vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
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err = register_oom_notifier(&vb->nb);
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if (err < 0)
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goto out_oom_notify;
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vb->thread = kthread_run(balloon, vb, "vballoon");
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if (IS_ERR(vb->thread)) {
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err = PTR_ERR(vb->thread);
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@ -452,6 +503,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
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return 0;
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out_del_vqs:
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unregister_oom_notifier(&vb->nb);
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out_oom_notify:
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vdev->config->del_vqs(vdev);
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out_free_vb:
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kfree(vb);
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@ -476,6 +529,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
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{
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struct virtio_balloon *vb = vdev->priv;
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unregister_oom_notifier(&vb->nb);
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kthread_stop(vb->thread);
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remove_common(vb);
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kfree(vb);
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@ -515,6 +569,7 @@ static int virtballoon_restore(struct virtio_device *vdev)
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static unsigned int features[] = {
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VIRTIO_BALLOON_F_MUST_TELL_HOST,
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VIRTIO_BALLOON_F_STATS_VQ,
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VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
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};
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static struct virtio_driver virtio_balloon_driver = {
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@ -81,7 +81,7 @@ void *virtqueue_get_used(struct virtqueue *vq);
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/**
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* virtio_device - representation of a device using virtio
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* @index: unique position on the virtio bus
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* @failed: saved value for CONFIG_S_FAILED bit (for restore)
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* @failed: saved value for VIRTIO_CONFIG_S_FAILED bit (for restore)
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* @config_enabled: configuration change reporting enabled
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* @config_change_pending: configuration change reported while disabled
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* @config_lock: protects configuration change reporting
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@ -31,6 +31,7 @@
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/* The feature bitmap for virtio balloon */
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#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
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#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
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#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
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/* Size of a PFN in the balloon interface. */
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#define VIRTIO_BALLOON_PFN_SHIFT 12
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