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Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Zi Yan Subject: [PATCH v3 06/24] mm/balloon_compaction: centralize adjust_managed_page_count() handling Date: Tue, 20 Jan 2026 00:01:14 +0100 Message-ID: <20260119230133.3551867-7-david@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260119230133.3551867-1-david@kernel.org> References: <20260119230133.3551867-1-david@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 9g9pgagfr3ej8p6ukwkgifgm8jdw5zox X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: BEF5A2000B X-HE-Tag: 1768863744-735878 X-HE-Meta: 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 jH713vVN 1Qs41/C0xHFp2znRNYVTCyom6b5br9nKEpzXiB6rnW2xUb+7GxywcBsQG0FDeHLS34YFcP9JXdi6BxFcyZGb4qcCNs1lmM0wpGAxMyKzbUMdGu+M4NM7JzbpFsftXQrNQQvqrNFmTx0q4FKf0IDtxasCUBd64ftd5lPfrqUrdwAclbfVjPeVXxEWaRnWpxenBf1V+PDfcdsez83GwjyqAJl+xitMTU/CFErEH4BwgJ7M5gR/W6Gn+ZHUWJ18MPkpLsvmZSDLduqE9p/gEbfw5CEkLtLBN6GFxH8N+f1mdM/vY/B3Z5q1toPxQRhVO30R38kVo78Iet9P3hKQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Let's centralize it, by allowing for the driver to enable this handling through a new flag (bool for now) in the balloon device info. Note that we now adjust the counter when adding/removing a page into the balloon list: when removing a page to deflate it, it will now happen before the driver communicated with hypervisor, not afterwards. This shouldn't make a difference in practice. Acked-by: Liam R. Howlett Acked-by: Michael S. Tsirkin Signed-off-by: David Hildenbrand (Red Hat) --- arch/powerpc/platforms/pseries/cmm.c | 13 +------------ drivers/virtio/virtio_balloon.c | 19 ++----------------- include/linux/balloon_compaction.h | 2 ++ mm/balloon_compaction.c | 17 +++++++++++++++++ 4 files changed, 22 insertions(+), 29 deletions(-) diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c index 15f873f733a41..7fd8b3d7e7637 100644 --- a/arch/powerpc/platforms/pseries/cmm.c +++ b/arch/powerpc/platforms/pseries/cmm.c @@ -165,7 +165,6 @@ static long cmm_alloc_pages(long nr) balloon_page_enqueue(&b_dev_info, page); atomic_long_inc(&loaned_pages); - adjust_managed_page_count(page, -1); nr--; } @@ -190,7 +189,6 @@ static long cmm_free_pages(long nr) if (!page) break; plpar_page_set_active(page); - adjust_managed_page_count(page, 1); __free_page(page); atomic_long_dec(&loaned_pages); nr--; @@ -515,16 +513,6 @@ static int cmm_migratepage(struct balloon_dev_info *b_dev_info, return -EBUSY; } - /* - * When we migrate a page to a different zone, we have to fixup the - * count of both involved zones as we adjusted the managed page count - * when inflating. - */ - if (page_zone(page) != page_zone(newpage)) { - adjust_managed_page_count(page, 1); - adjust_managed_page_count(newpage, -1); - } - /* * activate/"deflate" the old page. We ignore any errors just like the * other callers. @@ -551,6 +539,7 @@ static int cmm_init(void) return -EOPNOTSUPP; balloon_devinfo_init(&b_dev_info); + b_dev_info.adjust_managed_page_count = true; if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) b_dev_info.migratepage = cmm_migratepage; diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index df2756c071dae..15c1cf5fd249c 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -274,9 +274,6 @@ static unsigned int fill_balloon(struct virtio_balloon *vb, size_t num) set_page_pfns(vb, vb->pfns + vb->num_pfns, page); vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; - if (!virtio_has_feature(vb->vdev, - VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - adjust_managed_page_count(page, -1); vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; } @@ -295,9 +292,6 @@ static void release_pages_balloon(struct virtio_balloon *vb, struct page *page, *next; list_for_each_entry_safe(page, next, pages, lru) { - if (!virtio_has_feature(vb->vdev, - VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) - adjust_managed_page_count(page, 1); list_del(&page->lru); put_page(page); /* balloon reference */ } @@ -839,17 +833,6 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info, if (!mutex_trylock(&vb->balloon_lock)) return -EAGAIN; - /* - * When we migrate a page to a different zone and adjusted the - * managed page count when inflating, we have to fixup the count of - * both involved zones. - */ - if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) && - page_zone(page) != page_zone(newpage)) { - adjust_managed_page_count(page, 1); - adjust_managed_page_count(newpage, -1); - } - /* balloon's page migration 1st step -- inflate "newpage" */ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE; set_page_pfns(vb, vb->pfns, newpage); @@ -958,6 +941,8 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_free_vb; + if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) + vb->vb_dev_info.adjust_managed_page_count = true; #ifdef CONFIG_BALLOON_COMPACTION vb->vb_dev_info.migratepage = virtballoon_migratepage; #endif diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h index 7cfe48769239e..3109d3c43d306 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -56,6 +56,7 @@ struct balloon_dev_info { struct list_head pages; /* Pages enqueued & handled to Host */ int (*migratepage)(struct balloon_dev_info *, struct page *newpage, struct page *page, enum migrate_mode mode); + bool adjust_managed_page_count; }; extern struct page *balloon_page_alloc(void); @@ -73,6 +74,7 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) spin_lock_init(&balloon->pages_lock); INIT_LIST_HEAD(&balloon->pages); balloon->migratepage = NULL; + balloon->adjust_managed_page_count = false; } #ifdef CONFIG_BALLOON_COMPACTION diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 764fa25dc4bd1..4fe2a0cff69ec 100644 --- a/mm/balloon_compaction.c +++ b/mm/balloon_compaction.c @@ -23,6 +23,8 @@ static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info, BUG_ON(!trylock_page(page)); balloon_page_insert(b_dev_info, page); unlock_page(page); + if (b_dev_info->adjust_managed_page_count) + adjust_managed_page_count(page, -1); __count_vm_event(BALLOON_INFLATE); inc_node_page_state(page, NR_BALLOON_PAGES); } @@ -95,6 +97,8 @@ size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info, continue; list_del(&page->lru); + if (b_dev_info->adjust_managed_page_count) + adjust_managed_page_count(page, 1); balloon_page_finalize(page); __count_vm_event(BALLOON_DEFLATE); list_add(&page->lru, pages); @@ -264,9 +268,22 @@ static int balloon_page_migrate(struct page *newpage, struct page *page, get_page(newpage); balloon_page_insert(b_dev_info, newpage); __count_vm_event(BALLOON_MIGRATE); + + if (b_dev_info->adjust_managed_page_count && + page_zone(page) != page_zone(newpage)) { + /* + * When we migrate a page to a different zone we + * have to fixup the count of both involved zones. + */ + adjust_managed_page_count(page, 1); + adjust_managed_page_count(newpage, -1); + } } else { /* Old page was deflated but new page not inflated. */ __count_vm_event(BALLOON_DEFLATE); + + if (b_dev_info->adjust_managed_page_count) + adjust_managed_page_count(page, 1); } b_dev_info->isolated_pages--; -- 2.52.0