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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38ecb716751sm32721331fa.29.2026.04.21.06.16.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 06:17:02 -0700 (PDT) Date: Tue, 21 Apr 2026 09:16:56 -0400 From: "Michael S. Tsirkin" To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Johannes Weiner , Zi Yan , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu Subject: Re: [PATCH RFC v2 17/18] mm: add free_frozen_pages_hint and put_page_hint APIs Message-ID: <20260421091546-mutt-send-email-mst@kernel.org> References: <5f76af6e-9818-42ea-a305-c0fc1d920dca@kernel.org> MIME-Version: 1.0 In-Reply-To: <5f76af6e-9818-42ea-a305-c0fc1d920dca@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: arUaN7k6x7lVAgxGoET0bUk6jjgvgebg33OKuf9TP1E_1776777424 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: D4C2E180008 X-Stat-Signature: d1fe5bon98jpcjo4864eofr88cfoafyu X-Rspam-User: X-HE-Tag: 1776777427-539986 X-HE-Meta: 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 zWEDXxYP YbzDn9kg7IKrmiKZA9IzO73N3JSl2C3nLOTMWaaw+H1S7UFd+WTiopSeazHLjVSRXHTmn4zP5pKg8uH+H9BtQMdHvdwd/VgbpZhGMlhGuHT5bUwDbchqMl0RE88/NX7+kwIguKa0dPOwtPuJSoLGfwHDeytThPgvd1FEwZXOSrADDIgw+dENImAF8604tiT7wemA0IUOK2VmxDi6k72Dc0c4P3wZJa94SgGXKO5q4sgwsmEVuNloa/oMzzq+u2vtYBoJZDN2nDYojT+N3zZ8V3wgncFpcsMU8tdDvH2yoyKbVUr6fUuOOWz1fNKslZPCJ4wkHHGwxhQHQGuH9nEA6UNWVUtQSNpgSfZXkMAciZaqYYmoEcTtq5l1QPLe4LdymJART Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 21, 2026 at 12:56:00PM +0200, David Hildenbrand (Arm) wrote: > On 4/20/26 14:51, Michael S. Tsirkin wrote: > > Add free_frozen_pages_hint(page, order, hints) to free a page > > while marking it as pre-zeroed when PGHINT_ZEROED is set. > > The PG_zeroed flag is set after __free_pages_prepare so it > > survives on the free list. > > > > Add __folio_put_hint(), folio_put_hint(), and put_page_hint() > > wrappers for the put_page path. > > Can we defer that change? We can - it's a dependency of the balloon deflate, which you asked me to implement. I'm more interested in reporting, myself. > Putting a page with a hint, when there might still be other users of the > page is a weird interface. The hint is just ignored in this case. > In the long term, all balloon pages (PG_offline pages) will be frozen > pages, and definitely not folios. > > Frozen pages don't have a refcount. > > It would then be sufficient to have the single owner of the page call > something like free_frozen_zeroed_page(). > > Now, to convert balloon pages to be frozen requires some more work, > primarily to balloon migration handling, unfortunately. I have it on my > todo list, but it will take a while. > > -- > Cheers, > > David