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Peter Anvin" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Miaohe Lin , Naoya Horiguchi , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Catalin Marinas , Will Deacon , Mark Rutland , kas@kernel.org, kexec@lists.infradead.org, Brendan Jackman , Johannes Weiner , Zi Yan , shakeel.butt@linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-arm-kernel@lists.infradead.org, rmikey@meta.com, riel@surriel.com, harry@kernel.org, kernel-team@meta.com Subject: Re: [PATCH v6 4/7] mm/memblock: add a reserved-region flag for poisoned frames Message-ID: References: <20261016-hwpoison-kho-v6-0-f304255147da@debian.org> <20261016-hwpoison-kho-v6-4-f304255147da@debian.org> <524ee7d9-790d-48b6-8613-841da042c32a@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: C89B7100003 X-Stat-Signature: 8bxeqyu9twjozwxk8i6hxz4rxy1ggyt3 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-Rspamd-Server: rspam09 X-HE-Tag: 1793207603-481954 X-HE-Meta: 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 iZYQchlh I9SUJLBYyMfKbEXhHhMqOavfYM/TmxQM3/w5R/ERxRV7OU6ic/+O07CW8H9zTqj3m/fc09IREs2BeJ3atoiEIVB160ag27D2jYVMvhhlw6XrlSJS6rppgG5M8aJTOs1OCIcNl+Wf1Nj4BWHN6qo+JFVq+exbcGqPskoeUI1YgvMsX7miA/QNgMConFggeZ5n6OlW16OTSDJBlC1z3xmDyF6+oT3851FGEN6dmShPv9VbJgKNXFpONQp85s1Uxw75YaJOqhEmKJK1SC0M+mvAzd/kOWDfbbgYav619f4Qo0Z321LQ1SAV6G10q8v/JZ89k9Y5VeEcFEVadvls= 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 Wed, Oct 28, 2026 at 06:49:18AM -0700, Breno Leitao wrote: > On Wed, Oct 28, 2026 at 09:39:42AM +0100, David Hildenbrand (Arm) wrote: > > On 10/22/26 18:33, Mike Rapoport wrote: > > > Hi Breno, > > > > > > On Fri, Oct 16, 2026 at 05:15:44AM -0700, Breno Leitao wrote: > > >> memblock allocates from and frees to buddy whatever is not reserved, and > > >> knows nothing about frames an earlier kernel found hardware-poisoned. > > >> Such a frame can back the memmap, a page table or a percpu area before > > >> any hwpoison code runs, and otherwise reaches the buddy allocator like > > >> any other free frame. > > >> > > >> Add MEMBLOCK_RSRV_HWPOISON for a reserved range holding those frames. > > > > > > How much this would fragment memblock.reserved? > > > > > > memblock is not very scalable, to say the least, and each new flag > > > increases the size of memblock arrays which obviously hurts performance. > > > > I assume that if you have too many regions there, you have different problems > > than scalability problems. Not different, the problems are additive :) > > We should cut out larger chunks, and if they are all over your address space you > > should scrap that machine. > > Ack, that is what the 2M unit does. A DRAM row fault shows up as many 4K > pages but lands in one or two units, and adjacent units share one > memblock.reserved region. > > Mike, on the statistics you asked for: across the Meta hosts that logged > a hard memory failure in the last 28 days, these are the > memblock.reserved regions each host would need: > > p50 p90 p99 > x86 1 4 41 > arm64 1 5 27 Thanks! A new flag is fine by me. I'm still trying to parse what your LLM wrote in the commit messages before sending the tags ;-) > Thanks, > --breno -- Sincerely yours, Mike.