From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2751606A31E for ; Wed, 28 Oct 2026 17:13:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=vrlHWOVH; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=BZ6enJrj DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=vktowsTsOQhJmqiWYNIb0aPqBLNSbNahOroQ81vALNQ=; b=vrlHWOVHioN0H9vLANk43RJI0N DxBD/2882cQ3L1NA0Du+V0Td5WJKIwjA+dZYnsBcTuWdiHRJAy1iryNE1IEn7ayIllZJ6CXT1mwYT 2q6BR0Ic2qNC8o7W/aMOvB/q/oRX5NDLZrSwiJS6wHPZoGoYxTtGMqONmBWwVaLqty1vERzssDpGG 5FTZw0D3nfXwJBmI89H8lvbvD20W17C8zZManGaqlcIzf0E0JRxuD4ak51kgHaYMUlgvIruVO5eDS h+0FKUZTpgUqSaOwVg4eNBdaDwfHfFiin5BFUCTWZoYLA9JZMnjJG7O1U3zyUHM+tynZvnXEK7GLD QyPKJU1A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM7DI-00000007e0G-2dpC; Wed, 28 Oct 2026 17:13:24 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM7DH-00000007dzq-2kk8; Wed, 28 Oct 2026 17:13:23 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9A6F242CBD; Wed, 28 Oct 2026 17:13:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75E631F031E0; Wed, 28 Oct 2026 17:13:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793207602; bh=vktowsTsOQhJmqiWYNIb0aPqBLNSbNahOroQ81vALNQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BZ6enJrj2fR+WiaobREMK06Ol4IBWooQRDlbbDCkO1gNP7+G2R9/lsOOs2AhduaH8 IcGiH6/qAIxcfuSrwBdneQYRZt+W8ihxfi/bu8MIRkDPSGPjLv1CElqLHZjheiMzWZ DH0T5HoxcIR4+yigsaET5t4ctAredW023hZHdikTpcSGKdBksnJ3GuslAURAOE73r0 OFDzAYx+euSlpwhkJz6vzjSi4qGr9oAaq/5t/Y26Gl7SwP46yh6RZXFHOGQCNEJN9I lo7RodJkVz/gLSXqyhniNMQsfTsQPbnnv/5roVKerewBTdFEwzrN4Aepm6Xp3XPTM4 cnbju0zmHk6eA== Date: Wed, 28 Oct 2026 19:13:06 +0200 From: Mike Rapoport To: Breno Leitao Cc: "David Hildenbrand (Arm)" , Ard Biesheuvel , Ilias Apalodimas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 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.