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AJvYcCViJgjYz/YS15aPK09QHOvk9ZENePfCdE5eft8hwAgSVpeYBLdGqiLq8qaK5UWBZ8jk4wR0K7Io/Q==@kvack.org X-Gm-Message-State: AOJu0YypbCSCEQ2r+a55LibjCAfNOdj4dzXuDkLCVQ4MznFadjbOnCZD zXFrBuBe/rQzFOahLOYXiHoRgey0OuSPoVv6gNbg08LuWORBQzMjB4CYH7vkcb0B+ICWWvSkYZx w+n2YWk3xGTyauYfgJLA0K2W73vg= X-Gm-Gg: ASbGncsKgQ0RzU8vmUWto5PLaiNuBjTAKzgKt8qZ817/jTgLVE3xI2FuqVcp+2s4QeO MIY7HTyFU0jtPIBxXgxCpUNQMZytl7V4geunlkBwoGVVqwBYJPo53t3P0kuB9elj4 X-Google-Smtp-Source: AGHT+IE2j8nMVwwieWnYhj9zVCBibgsHGd2l2njO6mGc1HxgABCtbv9D6lAVtDCAdErXeO/T/MNVNBvmdywhZsimbPE= X-Received: by 2002:a05:6512:e9e:b0:540:206b:c358 with SMTP id 2adb3069b0e04-540206bc3d9mr223268e87.20.1733703452769; Sun, 08 Dec 2024 16:17:32 -0800 (PST) MIME-Version: 1.0 References: <20241125210149.2976098-1-willy@infradead.org> <839ce57b-c8be-4d78-8589-f2ee1ea91d28@suse.cz> In-Reply-To: <839ce57b-c8be-4d78-8589-f2ee1ea91d28@suse.cz> From: Hyeonggon Yoo <42.hyeyoo@gmail.com> Date: Mon, 9 Dec 2024 09:17:20 +0900 Message-ID: Subject: Re: [PATCH v3 00/15] Allocate and free frozen pages To: Vlastimil Babka Cc: "Matthew Wilcox (Oracle)" , Andrew Morton , linux-mm@kvack.org, David Hildenbrand Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D7C9F14000C X-Stat-Signature: pz47cg63fd9s3h6irrmw3kqiximibx3y X-Rspam-User: X-HE-Tag: 1733703439-991587 X-HE-Meta: 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 7qhmyaGU KeaLFWlA6rppxqFtSP3gVNtDyUJ7uC9Jv40ukU7xTgselHrhkBoKHGo4LmmiL9QcuaLmBnnV6LwFqIP7TainBALMCA0dGfNeZO/3UFgL7+03YNp3/9pvSHiffz9NuH4yOQoXBJRiAMJag1HoTK2xm2DNj4W6U7ISgRd2b2FfsymNbhW9WUaN4mIIYm3Puv6Id2qYmG7xbnhatdw6GQU+ORUB4yMxHCpp8YEowLg5zg6PcB/TrZL3/rtOabmVTTRFtSoPP+6E+iGjQNo5StwacIw6839OU1zM22xIN2Hmvj9R0EQ4NDwRF3tfBBXQCahOm/HEG0K+Mh2UPPWFYC1hHB6/la8ZGBb1FEUwz8sNrILj9B39Iuy95HugPWdE/ss2LweCxePkgEvzmmQkvGrEmxbFRLKnQwqqx+Xalh4MPCKvRacgAjXXhYzfYuQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.040508, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Dec 5, 2024 at 1:07=E2=80=AFAM Vlastimil Babka wro= te: > > On 11/26/24 06:04, Hyeonggon Yoo wrote: > > On Tue, Nov 26, 2024 at 7:38=E2=80=AFAM Matthew Wilcox (Oracle) > > wrote: > >> > >> Slab does not need to use the page refcount at all, and it can avoid > >> an atomic operation on page free. Hugetlb wants to delay setting the > >> refcount until it has assembled a complete gigantic page. We already > >> have the ability to freeze a page (safely reduce its reference count t= o > >> 0), so this patchset adds APIs to allocate and free pages which are in > >> a frozen state. > > > > [+Cc Vlastimil] > > > > I think with this patchset, we can finally remove the memory barriers u= sed > > in isolate_movable_page(), alloc_slab_page(), and __free_slab(), > > because folio_get_nontail_page() should fail for frozen pages? > > Thanks for the heads-up! > > > for reference, the patch that introduced the memory barrier: > > https://lore.kernel.org/linux-mm/Y20BRJmRzRVMzoJw@hyeyoo > > Are you going to sent the necessary patch on top of this series then? :) I will send it after some testing. > We could route it via -mm to avoid waiting a cycle or needing extra > synchronization. It's not a pure slab change anyway... Agreed. Will route it via mm. Best, Hyeonggon > > Thanks, > Vlastimil > > > Best, > > Hyeonggon >