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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Arnd Bergmann , Greg Kroah-Hartman , Jerrin Shaji George , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Zi Yan Subject: [PATCH v2 05/23] mm/balloon_compaction: centralize adjust_managed_page_count() handling Date: Thu, 15 Jan 2026 10:19:55 +0100 Message-ID: <20260115092015.3928975-6-david@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115092015.3928975-1-david@kernel.org> References: <20260115092015.3928975-1-david@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 6gspjd5t93pim4b7upr1ytgsbzn676se X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 236C1140009 X-Rspam-User: X-HE-Tag: 1768468859-374963 X-HE-Meta: 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 suF0Wn8F 6NX8iEsZ6ke2YqdHAkVNkp/tFhGFBRIRQBL+F8TTeFsLJIb7uN5pOQxa6T7NgmGFRqAUwJgmLEgpgc43TlMcE3VeiyqlmH635OCgGSCt0447b1voK6M5aLi7BvYNgfWQg6H9S/Tn/KWAlVLWVa/nvXEnQFjc0qubfpwom1nYm78kIXn4Siap931an0DVAF2x1QtNuBqMepzCKxXhCt8qNoTRe89Jq9h/egwADZ+o2wEUEZSpbFVophuyZGCFlOk91XaMH9AIkQLoWL6NfTB48EXr2Qg== 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. 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 5444c61bb9e76..fd9ec47cf4670 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); @@ -256,12 +260,25 @@ static int balloon_page_migrate(struct page *newpage, struct page *page, 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); + } break; case -ENOENT: spin_lock_irqsave(&b_dev_info->pages_lock, flags); /* 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); break; default: return rc; -- 2.52.0