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[129.46.96.20]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-679f2bfee3csm1013246eaf.7.2026.02.25.23.01.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 23:01:27 -0800 (PST) From: Yuvraj Sakshith To: akpm@linux-foundation.org, mst@redhat.com, david@kernel.org Cc: vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, virtualization@lists.linux.dev, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 0/3] Allow order zero pages in page reporting Date: Wed, 25 Feb 2026 23:01:22 -0800 Message-Id: <20260226070125.3732265-1-yuvraj.sakshith@oss.qualcomm.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: 9ncrRu9lL-ow31NjMEw-e9LzsHZ0Gkut X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI2MDA2MSBTYWx0ZWRfXw2LCC80rzcWC LtUOiThjavo8h0fnWAkuv3xrwW+hXKYfTAsUJHuqF3VdREYPVny+P/pjp4dZjVj+GmAxCXIdKZD ARTWec0YIW9W70LZRUQpp40TRAalT7lR/eh2DKWBee2o0zKPukBYK7pcgX9C44pz6HfciYhIBs2 tUHPUI8vhirOr6+Xe8+oN5XvtxlK8ZEoGdNMnhT0LLRFuuAM1mBH+1ppxGXajpooqki3LKPKSni YGrJ5yKaA1/tzKYPBSzpPZZPhEB3fcarQj46dbdP+0i5/Bb6M1RcmSRTSw9X5m8WZDfke8hFWPA nr2xUkXGqAHXdrcrnjbQ9TcGHxkHv1jKRuehOzDCJkhTnichFmeeSywKiT3EaX3v9v3gJN5yafD zqFRcme+HgnZ86eQGUmJDD1uMcS5LPHcv8s9kd9mChwUzZX2skNp4a4BgGuNbTQFAw8wxGIiVrI vLYEkfOSaXDBG4qpV6g== X-Authority-Analysis: v=2.4 cv=GZwaXAXL c=1 sm=1 tr=0 ts=699fefc9 cx=c_pps a=lVi5GcDxkcJcfCmEjVJoaw==:117 a=ouPCqIW2jiPt+lZRy3xVPw==:17 a=HzLeVaNsDn8A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=9ecvtSpfVrh-a2M179QA:9 a=rBiNkAWo9uy_4UTK5NWh:22 X-Proofpoint-GUID: 9ncrRu9lL-ow31NjMEw-e9LzsHZ0Gkut X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-25_04,2026-02-25_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1011 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2602260061 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 153D9140004 X-Stat-Signature: 8a3tdn9pbtdumibbdqyogizpgsuchaze X-HE-Tag: 1772089289-151438 X-HE-Meta: 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 tGh9rv1R 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Today, page reporting sets page_reporting_order in two ways: (1) page_reporting.page_reporting_order cmdline parameter (2) Driver can pass order while registering itself. In both cases, order zero is ignored by free page reporting because it is used to set page_reporting_order to a default value, like MAX_PAGE_ORDER. In some cases we might want page_reporting_order to be zero. For instance, when virtio-balloon runs inside a guest with tiny memory (say, 16MB), it might not be able to find a order 1 page (or in the worst case order MAX_PAGE_ORDER page) after some uptime. Page reporting should be able to return order zero pages back for optimal memory relinquishment. This patch changes the default fallback value from '0' to '-1' in all possible clients of free page reporting (hv_balloon and virtio-balloon) together with allowing '0' as a valid order in page_reporting_register(). Yuvraj Sakshith (3): mm/page_reporting: Allow zero page_reporting_order hv_balloon: Change default page reporting order virtio_balloon: Set pr_dev.order to new default drivers/hv/hv_balloon.c | 2 +- drivers/virtio/virtio_balloon.c | 14 ++++++++++++++ mm/page_reporting.c | 2 +- 3 files changed, 16 insertions(+), 2 deletions(-) -- 2.34.1