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b=WdAKNk1hWm3DX8qCSqa7BmET/VUYWlGAiMYdrMjsuaX41rYPyBHVMB+q12pm22Vrv rBqn9IWfSxYleSP6P4jyohMRicda6JSV2BzlKydRxOh2xWNEVtFbxmPDlSVisR316X q7x4fgGqRjOPywcvXoPk+yXbBb9pxIPyEPJ2lChanfBYSjqzo55+npSk53iJZOXWuJ x5NVxFEMeCE6kkUHB1rwzRx88EOl5OJuOth3QofJnhftx81+He3b3ZKev+26Kkj7ll ewUlqp6vlnDeSar9607LapxHYwgAVguPFqBDrkcfVxONYTkGHcKzzgTUr8Vpn7fblO Z7gUz3+bu5Q8g== Date: Mon, 1 Dec 2025 08:54:37 +0200 From: Mike Rapoport To: Pratyush Yadav Cc: Andrew Morton , Alexander Graf , Pasha Tatashin , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kho: fix restoring of contiguous ranges of order-0 pages Message-ID: References: <20251125110917.843744-1-rppt@kernel.org> <20251125110917.843744-3-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BDCEE140002 X-Stat-Signature: hsbs9gotgfa9qzxj3xwwdhwaimpack4b X-Rspam-User: X-HE-Tag: 1764572084-710152 X-HE-Meta: U2FsdGVkX18mkqIus8/Wl0S80It5vbdhyTy9J5HwgQ1kKjuA4jHI8Vm/lDDnPYYoL2oclk186YRzVAh231uaPmQo3af6b+nZbTxyAmPzFz47uFlVJ75foebA14OkmEPqP8iafD7aJVzvn0TCoGtRfF5+lDEy/uqLWnolwMRmn2Yjek2ybEllCReLa7+aWsidQ+B6vf3gxvDapcTaO6TMsQ/hB5UTuaY0gPWaR5DgUJ59OZRbF8Ngwx8mdMBKHG9R+oTNTFPp64YJdSmnd5cPXO4ZK9FZaHL9eR1oMMIWrUlUcTh1HZi/Tj487XPXTcaFogRvrXujxp6CVOenvdia4myRxtU84gEnZvVUq4IVNooBPrKn+29DgG9wAHDCrhoSTKy6mL7gcv3H7RQNfruf3OWyUrbM1AKiXWnl3Zcan/kVqjmIAtj/JpGPNggqD9HgeIAxd4NviRqrO7lJI/H5EskfX0OmTmKcFW/sfd/cOMl8JtJMwvO2mZhL2YNBirkcuh+p8BDH/DK75Cgw5bQp8MAoMdtobvyll4vO4snfBqnaryb3djTHUQ5FuGOf8ZLa/fX8/9hBA1KZoOzV3SCCHZ/GRcNfHVOtjUti270RcRRypdcOsPZz0qLz/egRGdesZpWYxa/Opp9mZrYEIpSYe9qKCoXJIQmkkdx0ycobjNN9SA8KRu7g8D1wBVPIT58vOtNrJATMfz3fqCLNlta1ZKTZaFX/I8sPzHdgccO3xJzUPwEi6Ul2qgDZRYgadTFu3xuOT5BVE6ovlN1l8sgePC5zZjCaVAa7eodlyUZuAC9TJV/DKpDlppYkTUfrYEsFF65xg2pcQHK9hfxIJMZamePsn9OG+je6vCUxkH4cw9YQf+XA6yN8va438MqtPeYzPCFGqlv6W6ctRHReY17PUp0J+gEUUeS5jVTtzQ97k4LoD4kio9cCA5iyklg9vk3C6ONHSOhMdaXjOeqfB8i yQSI/iG8 YHKuScGB9xZCCrket1UYj9vVptWM7kO6nVUGM4iP6kO3ehjpQiCIcYXM23xGZEZQQRz13t7CAjLn03hCYfVXJZaaolDj0CoyGSqAn2OmKegzvkp0CPkckDVdhpmAotsQ47hM8T9ZZa03wTzLhXEtI2XmQ5eIK9N5gtkVtb2oC0g1Z/5G9gdxpO6uCSdea8yX/sojQemk8Zdu4rvNFd82miizVXTCi2FWS1yZxW0IM94zq8kygz2SBVTmkqBHII9XMc4Cu 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: Hi Pratyush, On Tue, Nov 25, 2025 at 02:45:59PM +0100, Pratyush Yadav wrote: > On Tue, Nov 25 2025, Mike Rapoport wrote: ... > > @@ -243,11 +243,16 @@ static struct page *kho_restore_page(phys_addr_t phys) > > /* Head page gets refcount of 1. */ > > set_page_count(page, 1); > > > > - /* For higher order folios, tail pages get a page count of zero. */ > > + /* > > + * For higher order folios, tail pages get a page count of zero. > > + * For physically contiguous order-0 pages every pages gets a page > > + * count of 1 > > + */ > > + ref_cnt = is_folio ? 0 : 1; > > for (unsigned int i = 1; i < nr_pages; i++) > > - set_page_count(page + i, 0); > > + set_page_count(page + i, ref_cnt); > > > > - if (info.order > 0) > > + if (is_folio && info.order) > > This is getting a bit difficult to parse. Let's separate out folio and > page initialization to separate helpers: Sorry, I've missed this earlier and now the patches are in akpm's -stable branch. Let's postpone these changes for the next cycle, maybe along with support for deferred initialization of struct page. > /* Initalize 0-order KHO pages */ > static void kho_init_page(struct page *page, unsigned int nr_pages) > { > for (unsigned int i = 0; i < nr_pages; i++) > set_page_count(page + i, 1); > } > > static void kho_init_folio(struct page *page, unsigned int order) > { > unsigned int nr_pages = (1 << order); > > /* Head page gets refcount of 1. */ > set_page_count(page, 1); > > /* For higher order folios, tail pages get a page count of zero. */ > for (unsigned int i = 1; i < nr_pages; i++) > set_page_count(page + i, 0); > > if (order > 0) > prep_compound_page(page, order); > } -- Sincerely yours, Mike.