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Howlett" , Lorenzo Stoakes , Michal Hocko , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: Re: [PATCH 0/2] mm/cma: accept memory of CMA areas reserved with memblock_reserve() Message-ID: References: <20261029-cma-multi-v1-0-2cbced8b5cb7@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 5E93480008 X-Stat-Signature: pz4dyg8o6zczpocwfjys7tm13rjokhq3 X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793277630-656015 X-HE-Meta: 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 hBoqcBZG hFCHo1m/HrxkMFYE3jHSHZwAxX/Gs6UoFxytfre+XG3GvC6UcC1sb5Mqj6SUU2lQdCE1ifHRfnYHJpRjQPi5fl7RwJ7n84VfrZo0CAUJ/3ZL3VZO2V/VAFqThjfkCkclHxRgMJ/9AJn0IAeDFn9YlhQGRl6nkjXyAVUGt8CH2PGYDnTU7WS76QWURBdmJtK7W9e8avxVMajqoK3KM5zKNmZ8TcH/slY/6OEpcID0Xx2jhyR5YRpl+BlrnI5KVxHLHM1d7glrrWgDM6O6cR6NWGKm8zNLmL4g+txGopyTbPErHfpg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Oct 29, 2026 at 12:27:23PM +0000, Kiryl Shutsemau wrote: > On Thu, Oct 29, 2026 at 12:18:36PM +0200, Mike Rapoport (Microsoft) wrote: > > Pages of allocated CMA areas are released to the buddy allocator with > > __free_pages(), which does not check for unaccepted memory. > > > > This usually works because memblock accepts the memory it allocates. > > > > However, multi-range CMA areas, used by hugetlb_cma, and fixed CMA areas > > requested with cma=@ are reserved with memblock_reserve() and > > their memory is never accepted. > > It feels like memblock_reserve() abuse, no? > > crashkernel=size@base already uses memblock_phys_alloc_range() for this. > Should the fixed and multi-range CMA paths go through the allocation API > as well. Fixed path already has the range, why would it use allocation APIs? The multi-range could, but it will be several times slower and I believe the intention was to avoid allocation APIs exactly because of that. > -- > Kiryl Shutsemau / Kirill A. Shutemov -- Sincerely yours, Mike.