From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B7BCC6778F for ; Fri, 27 Jul 2018 09:52:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00E9D20895 for ; Fri, 27 Jul 2018 09:52:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 00E9D20895 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389166AbeG0LN5 (ORCPT ); Fri, 27 Jul 2018 07:13:57 -0400 Received: from mga02.intel.com ([134.134.136.20]:27704 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730425AbeG0LN5 (ORCPT ); Fri, 27 Jul 2018 07:13:57 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Jul 2018 02:52:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,408,1526367600"; d="scan'208";a="78308893" Received: from devel-ww.sh.intel.com ([10.239.48.110]) by orsmga002.jf.intel.com with ESMTP; 27 Jul 2018 02:52:48 -0700 From: Wei Wang To: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org Cc: wei.w.wang@intel.com Subject: [PATCH v2 2/2] virtio_balloon: replace oom notifier with shrinker Date: Fri, 27 Jul 2018 17:24:55 +0800 Message-Id: <1532683495-31974-3-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1532683495-31974-1-git-send-email-wei.w.wang@intel.com> References: <1532683495-31974-1-git-send-email-wei.w.wang@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The OOM notifier is getting deprecated to use for the reasons mentioned here by Michal Hocko: https://lkml.org/lkml/2018/7/12/314 This patch replaces the virtio-balloon oom notifier with a shrinker to release balloon pages on memory pressure. In addition, the bug in the replaced virtballoon_oom_notify that only VIRTIO_BALLOON_ARRAY_PFNS_MAX (i.e 256) balloon pages can be freed though the user has specified more than that number is fixed in the shrinker_scan function. Signed-off-by: Wei Wang Cc: Michael S. Tsirkin Cc: Michal Hocko Cc: Andrew Morton --- drivers/virtio/virtio_balloon.c | 115 +++++++++++++++++++++++----------------- 1 file changed, 65 insertions(+), 50 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 9356a1a..6b2229b 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -27,7 +27,6 @@ #include #include #include -#include #include #include #include @@ -40,12 +39,12 @@ */ #define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) #define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256 -#define OOM_VBALLOON_DEFAULT_PAGES 256 +#define DEFAULT_BALLOON_PAGES_TO_SHRINK 256 #define VIRTBALLOON_OOM_NOTIFY_PRIORITY 80 -static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES; -module_param(oom_pages, int, S_IRUSR | S_IWUSR); -MODULE_PARM_DESC(oom_pages, "pages to free on OOM"); +static unsigned long balloon_pages_to_shrink = DEFAULT_BALLOON_PAGES_TO_SHRINK; +module_param(balloon_pages_to_shrink, ulong, 0600); +MODULE_PARM_DESC(balloon_pages_to_shrink, "pages to free on memory presure"); #ifdef CONFIG_BALLOON_COMPACTION static struct vfsmount *balloon_mnt; @@ -86,8 +85,8 @@ struct virtio_balloon { /* Memory statistics */ struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; - /* To register callback in oom notifier call chain */ - struct notifier_block nb; + /* To register a shrinker to shrink memory upon memory pressure */ + struct shrinker shrinker; }; static struct virtio_device_id id_table[] = { @@ -365,38 +364,6 @@ static void update_balloon_size(struct virtio_balloon *vb) &actual); } -/* - * virtballoon_oom_notify - release pages when system is under severe - * memory pressure (called from out_of_memory()) - * @self : notifier block struct - * @dummy: not used - * @parm : returned - number of freed pages - * - * The balancing of memory by use of the virtio balloon should not cause - * the termination of processes while there are pages in the balloon. - * If virtio balloon manages to release some memory, it will make the - * system return and retry the allocation that forced the OOM killer - * to run. - */ -static int virtballoon_oom_notify(struct notifier_block *self, - unsigned long dummy, void *parm) -{ - struct virtio_balloon *vb; - unsigned long *freed; - unsigned num_freed_pages; - - vb = container_of(self, struct virtio_balloon, nb); - if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - return NOTIFY_OK; - - freed = parm; - num_freed_pages = leak_balloon(vb, oom_pages); - update_balloon_size(vb); - *freed += num_freed_pages; - - return NOTIFY_OK; -} - static void update_balloon_stats_func(struct work_struct *work) { struct virtio_balloon *vb; @@ -548,6 +515,54 @@ static struct file_system_type balloon_fs = { #endif /* CONFIG_BALLOON_COMPACTION */ +static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, + struct shrink_control *sc) +{ + unsigned long pages_to_free = balloon_pages_to_shrink, + pages_freed = 0; + struct virtio_balloon *vb = container_of(shrinker, + struct virtio_balloon, shrinker); + + /* + * One invocation of leak_balloon can deflate at most + * VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it + * multiple times to deflate pages till reaching + * balloon_pages_to_shrink pages. + */ + while (vb->num_pages && pages_to_free) { + pages_to_free = balloon_pages_to_shrink - pages_freed; + pages_freed += leak_balloon(vb, pages_to_free); + } + update_balloon_size(vb); + + return pages_freed / VIRTIO_BALLOON_PAGES_PER_PAGE; +} + +static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + struct virtio_balloon *vb = container_of(shrinker, + struct virtio_balloon, shrinker); + + return min_t(unsigned long, vb->num_pages, balloon_pages_to_shrink) / + VIRTIO_BALLOON_PAGES_PER_PAGE; +} + +static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) +{ + unregister_shrinker(&vb->shrinker); +} + +static int virtio_balloon_register_shrinker(struct virtio_balloon *vb) +{ + vb->shrinker.scan_objects = virtio_balloon_shrinker_scan; + vb->shrinker.count_objects = virtio_balloon_shrinker_count; + vb->shrinker.batch = 0; + vb->shrinker.seeks = DEFAULT_SEEKS; + + return register_shrinker(&vb->shrinker); +} + static int virtballoon_probe(struct virtio_device *vdev) { struct virtio_balloon *vb; @@ -580,17 +595,10 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_free_vb; - vb->nb.notifier_call = virtballoon_oom_notify; - vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY; - err = register_oom_notifier(&vb->nb); - if (err < 0) - goto out_del_vqs; - #ifdef CONFIG_BALLOON_COMPACTION balloon_mnt = kern_mount(&balloon_fs); if (IS_ERR(balloon_mnt)) { err = PTR_ERR(balloon_mnt); - unregister_oom_notifier(&vb->nb); goto out_del_vqs; } @@ -599,13 +607,20 @@ static int virtballoon_probe(struct virtio_device *vdev) if (IS_ERR(vb->vb_dev_info.inode)) { err = PTR_ERR(vb->vb_dev_info.inode); kern_unmount(balloon_mnt); - unregister_oom_notifier(&vb->nb); vb->vb_dev_info.inode = NULL; goto out_del_vqs; } vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops; #endif - + /* + * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a + * shrinker needs to be registered to relieve memory pressure. + */ + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { + err = virtio_balloon_register_shrinker(vb); + if (err) + goto out_del_vqs; + } virtio_device_ready(vdev); if (towards_target(vb)) @@ -637,8 +652,8 @@ static void virtballoon_remove(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; - unregister_oom_notifier(&vb->nb); - + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) + virtio_balloon_unregister_shrinker(vb); spin_lock_irq(&vb->stop_update_lock); vb->stop_update = true; spin_unlock_irq(&vb->stop_update_lock); -- 2.7.4