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X-IronPort-AV: E=McAfee;i="6700,10204,11114"; a="152361441" X-IronPort-AV: E=Sophos;i="6.08,266,1712588400"; d="scan'208";a="152361441" Received: from unknown (HELO oym-r1.gw.nic.fujitsu.com) ([210.162.30.89]) by esa10.hc1455-7.c3s2.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jun 2024 15:03:10 +0900 Received: from oym-m2.gw.nic.fujitsu.com (oym-nat-oym-m2.gw.nic.fujitsu.com [192.168.87.59]) by oym-r1.gw.nic.fujitsu.com (Postfix) with ESMTP id D62E5C13D0; Wed, 26 Jun 2024 15:03:07 +0900 (JST) Received: from kws-ab3.gw.nic.fujitsu.com (kws-ab3.gw.nic.fujitsu.com [192.51.206.21]) by oym-m2.gw.nic.fujitsu.com (Postfix) with ESMTP id 4CC50BF4B7; Wed, 26 Jun 2024 15:03:06 +0900 (JST) Received: from edo.cn.fujitsu.com (edo.cn.fujitsu.com [10.167.33.5]) by kws-ab3.gw.nic.fujitsu.com (Postfix) with ESMTP id CB1EF2007CA91; Wed, 26 Jun 2024 15:03:05 +0900 (JST) Received: from [192.168.50.5] (unknown [10.167.226.114]) by edo.cn.fujitsu.com (Postfix) with ESMTP id 087111A0002; Wed, 26 Jun 2024 14:03:03 +0800 (CST) Message-ID: Date: Wed, 26 Jun 2024 14:03:03 +0800 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] cxl: avoid duplicating report from MCE & device To: "Luck, Tony" , Jonathan Cameron , "Williams, Dan J" Cc: "qemu-devel@nongnu.org" , "linux-cxl@vger.kernel.org" , "dave@stgolabs.net" , "Weiny, Ira" , "Schofield, Alison" , "Jiang, Dave" , "Verma, Vishal L" , Borislav Petkov , James Morse , Mauro Carvalho Chehab , Robert Richter , "linux-edac@vger.kernel.org" , Miaohe Lin , Naoya Horiguchi , "linux-mm@kvack.org" References: <20240618165310.877974-1-ruansy.fnst@fujitsu.com> <20240620180239.00004d41@Huawei.com> <6675bf92116ed_57ac294a@dwillia2-xfh.jf.intel.com.notmuch> <20240621194506.000024aa@Huawei.com> From: Shiyang Ruan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-TM-AS-Product-Ver: IMSS-9.1.0.1417-9.0.0.1002-28482.005 X-TM-AS-User-Approved-Sender: Yes X-TMASE-Version: IMSS-9.1.0.1417-9.0.1002-28482.005 X-TMASE-Result: 10--14.782900-10.000000 X-TMASE-MatchedRID: bdIiGNtle6uPvrMjLFD6eKn9fPsu8s0a2q80vLACqaeqvcIF1TcLYPAF 43IXaj2gSY/hjDx7hppvUDqCNlsvKH+zsg6kp2C3Q0Xm0pWWLkroUwvpyt4rucg9ufahCGm1l2i SdQmYgPCf4Zlhm+r+lc5cp47XA8AiC9QTSuTOQRl+J3gtIe0gA8qspZV+lCSLdBaEtWosUzVYTF /5quaSLwftggnq5tKUMTii0wFdgxqOeQ6RXnGCFkX/j4QZJ10NajzNTFMlQCNtfzoljzPXO9F8e 0i2JFlZ371UTvxX45vRKmOlruuzzop+5WdOMDCgv8fLAX0P50B2ZYwNBqM6IlLvEapiw2T1hXAr +h4GfTAIZNHliKo/PSm+XCxBE3RsKgAlgjPhYpaOtWfhyZ77Dn0tCKdnhB581B0Hk1Q1KyIOsEC O9s+GHnQdJ7XfU86eOwBXM346/+z07YdcTiNsP7Uv9Q5rrJhWezfWWH34ZgZxRwXGk1PHIsR47n 50KUDY X-TMASE-SNAP-Result: 1.821001.0001-0-1-22:0,33:0,34:0-0 在 2024/6/22 4:44, Luck, Tony 写道: >> So who actually cares about recovering poisoned volatile memory? >> I'd like to understand more on how significant a use case this is. >> Whilst I can conjecture that its an extreme case of wanting to avoid >> loosing the ability to create 1GiB or larger pages due to poison >> is that a real problem for anyone today? Note this is just the case >> where you've reached an actual uncorrectable error and probably >> / possibly killed something, not the more common soft offlining >> of memory due to correctable errors being detected. > > I guess you really need a reply from someone with a data center > with thousands of machines, since that's where this question > may be important. > > My humble opinion is that, outside of the huge page issue, nobody > should try to recover a poisoned page. Systems that can report > and recover from poison have tens, hundreds, or more GBytes > of memory. Dropping 4K pages will not have any measurable > impact on a system (even if there are hundreds of pages dropped). > > There's no reliable way to determine whether the poisoned page > was due to some transient issue, or a permanent defect. Recovering > a poisoned page runs the risk that the poison will re-occur. Perhaps > next use of the page will be in some unrecoverable (kernel) context. > > So recovery has some risk, but very little upside benefit. Since the hardware provides the instruction(CPU)/command(CXL) to clear the poison, we could make the function work, at least as an optional feature. Then users could decide to use it or not after evaluating the risk and benefit. I think doing recovery is an improvement step, and may need a lot of discussion. I'm not sure if we could reach a conclusion in this thread. Just hope more comments on the original problem (duplicate report) to solve in this patch. -- Thanks, Ruan. > > -Tony