From nobody Sat Feb 7 18:52:14 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1CBFB241665; Mon, 19 Jan 2026 23:02:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768863748; cv=none; b=K7IBI2bPKEbPPUxyj2qZJ4MIug9ZjlGcDWocq+wSeYYU7FmrOhHXqBMCBNgFum+W9+NIXaU28G8aXtgEwd+drYGXqBHudtRHVmceghhBCufOAR98RYQ9l4NqkSQ5XMVcdFyvE+OxX+mu5JV2QU6MFmh4jD8eUjH81GNx9281f6Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768863748; c=relaxed/simple; bh=SnhMKeXWJjdrWLtSbqKw7V4EMXVK/pgfK7VZwhJNF9w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o/1nTsnIG+17l7TpZfNjxktP0kxhPyT/GIzEegBwGqKWkZXN6QweXldCdrOvHhKweEVR0heQXSZKAxxgK+CZBDpR7Sx7mZ38we5Xznf1GNJZ2RyIgjWoaSg9Xf7ZahgwqszTSOvu98V9QFPjw5+pFCxdJDpbMmoPRkXZPRtxjw0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cwpscc+r; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Cwpscc+r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E383C19424; Mon, 19 Jan 2026 23:02:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768863743; bh=SnhMKeXWJjdrWLtSbqKw7V4EMXVK/pgfK7VZwhJNF9w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cwpscc+r+ZQnX9sK8UbIxMV80FOtiD0YmfSvImeyZ1PRPQH2lLEE20JaD3ObyynTS EGuheGjlkJBQOTWpsnYX+6heM102tLpDu6hT5riS/StPirtxFNFhQIt+gXzAzu7kUT Uzc4AuZlWiPVtXJnQFd63BCCJMA5kq3Amhls8qWKE7JNdROfRWhZztXHKUFcrYZNRw cVB+zSGrii6PulRMvxLEhh/ZRNUvVNnIvhFuWUFz+Uvo0liKLJgMoJUzmbMyXFccU9 /FyQCbCpzZq84lBXHcsEEz5XJxyaDrhzSquDZ/IjDQFhLnqPjvyS+ROF1QKGZ/ITAv Bphv7kbjcZ1ew== From: "David Hildenbrand (Red Hat)" To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Broadcom internal kernel review list , linux-doc@vger.kernel.org, virtualization@lists.linux.dev, "David Hildenbrand (Red Hat)" , Andrew Morton , Oscar Salvador , Lorenzo Stoakes , "Liam R. 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 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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) =20 balloon_page_enqueue(&b_dev_info, page); atomic_long_inc(&loaned_pages); - adjust_managed_page_count(page, -1); nr--; } =20 @@ -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; } =20 - /* - * 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) !=3D 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; =20 balloon_devinfo_init(&b_dev_info); + b_dev_info.adjust_managed_page_count =3D true; if (IS_ENABLED(CONFIG_BALLOON_COMPACTION)) b_dev_info.migratepage =3D cmm_migratepage; =20 diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloo= n.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) =20 set_page_pfns(vb, vb->pfns + vb->num_pfns, page); vb->num_pages +=3D 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 +=3D VIRTIO_BALLOON_PAGES_PER_PAGE; } =20 @@ -295,9 +292,6 @@ static void release_pages_balloon(struct virtio_balloon= *vb, struct page *page, *next; =20 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; =20 - /* - * 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) !=3D 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 =3D 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; =20 + if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) + vb->vb_dev_info.adjust_managed_page_count =3D true; #ifdef CONFIG_BALLOON_COMPACTION vb->vb_dev_info.migratepage =3D virtballoon_migratepage; #endif diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_com= paction.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; }; =20 extern struct page *balloon_page_alloc(void); @@ -73,6 +74,7 @@ static inline void balloon_devinfo_init(struct balloon_de= v_info *balloon) spin_lock_init(&balloon->pages_lock); INIT_LIST_HEAD(&balloon->pages); balloon->migratepage =3D NULL; + balloon->adjust_managed_page_count =3D false; } =20 #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_i= nfo *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; =20 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) !=3D 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); } =20 b_dev_info->isolated_pages--; --=20 2.52.0