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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: <524ee7d9-790d-48b6-8613-841da042c32a@kernel.org> X-Debian-User: leitao X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D3299140008 X-Stat-Signature: a9wjiwazdih6nthe5mwe6x8h1p37gqu5 X-Rspam-User: 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-HE-Tag: 1793195419-85301 X-HE-Meta: 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 Mg+ixmSL JZFYfflEiA/LF0X3aCrhqlw4qUlPzH0gzJrdQOg51SFtKei0JrEnUnfu9wLohdkJpNRq/prpG0WoVYx6hdcmDCCUdwpqXvnasyV0iqrfZ8LrdaOLE8Fizd0KUZQ5OxB3GTNvHExE2P1Jq9J8pFm8ZbHYQO0DJnCH6g4XcC6AIydQAwwTJlczfM+fmAaSrTtntFncP/vGe4YAsZ3pyfIZODUJBZJckxEC6DEKcYhanlSqkq5jxwESRApSJ/yKutTuqO/zN36B/U0LIwA6Jbcb6fZVjFg/vHYsntepdT0qb2bGEEgN5RGE2SUgATarsVFi4zIRK3gsBEGngTnw= 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 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. > > 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, --breno