From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=82.195.75.108 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793195416; b=VVP+bJzmRD4lZc7cuZwKzJHA4ZdEBeoO+Oo66YtjjeEniG2SD0Bfa6G5qOxG8zfw6vTy W6dkhuCabW5vvS/i/oIbJLQ97mxM4CJbHzy8VZc4cG9DHPDa2x8a1A2FNgsHy6+ljwS4I s+qPmm6BSXGxMvk3M3PW9woKCb1eSoW5rtk0pL7VqQC4cChUY6bvib77lUYtLOr9pfSbV 2dwBuDs2/ay840IOP1OQbp+bIwDWL1uuzvQOR7ktRuKSWg2zoim/tFO9EvPGNpzx3+/ol GnTdmoocz8jZ/FV65BedAw1GOT4bu7EcM29fSySotabnA0SZzqnqcOST7iyr/O+2qNg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793195416; h=DMARC-Filter:DKIM-Signature:Received:Date:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To:X-Debian-User; bh=EKOJSvQCyvmegciiDSA3qkq54znl6sRsTPqc7BTTnKg=; b=MQa5FSN/dUrwopcu6lSI0IkhedJOB9nwkQtJO83aBuL8Wnk1d38o6yt5ax1STwLVbFXE 5w/SREVRLKeAgYXAcjbDX463ZpZ9HtSgr5H6TIDTtBI5bR5qvU6gbqmUV1/u/2dqucvSn WWsB8VP58qphxfz875B6t1zC2YMBB5LT/dhIs+7KT2V38o5yyGUD7p77nGnTPaSItorRm /M6MKXyuNMZRQMO7yUAwsvynpJ6O807IeMPqvYvnqJWn5OFCYwsskfNT4hvbCC6Db3mF5 SR9x8agOvy8DOUMBO6kWFhwB/OCkLiVn+DriCvwZWKP2mMlSvMwDMtbyhDYUQaM6U9w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=BxUepWxa; arc=none smtp.remote-ip=82.195.75.108 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3131D606A32F; Wed, 28 Oct 2026 13:50:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3131D606A32F Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=BxUepWxa DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=EKOJSvQCyvmegciiDSA3qkq54znl6sRsTPqc7BTTnKg=; b=BxUepWxaQM94nl47RKcbqrBwZ7 kKjKjVjHXt+ZcHaBoC9nDp4oSN9ak/TO/XSgZcZWwNyUes07CsiuLocLH66v0bHNVj9IKB35ZiIBf fXcJPdkUhdzi3eVA3yYx2Wb11fbpqdcML3ik3qmNvo9oHUT+1pIV40JNfxDMJ/wmX9eR2jxICexSE ad3Hc1No0hfI+y0IgWiVtZAg0BshCR6qLOZqqp16nouHynXTJ9IQB4qiaP3+hFCWqYSQ+ZvQao6uQ gtgCbH3J+tJpJRCI+onTodJWcxHXBKOxtmizI01tTt3GIKNO4zPmrK05hh4otiSxEU/f4XlZ4mWb4 KFvceyFg==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1xM41u-002Ho4-0T; Wed, 28 Oct 2026 13:49:26 +0000 Date: Wed, 28 Oct 2026 06:49:18 -0700 From: Breno Leitao To: "David Hildenbrand (Arm)" Cc: Mike Rapoport , 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-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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 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