From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01BE5C433DB for ; Tue, 5 Jan 2021 07:51:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B467B2256F for ; Tue, 5 Jan 2021 07:51:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727246AbhAEHvQ (ORCPT ); Tue, 5 Jan 2021 02:51:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:41940 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727129AbhAEHvP (ORCPT ); Tue, 5 Jan 2021 02:51:15 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1609833029; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=zN1ZQptkDr2Sx20lZHpIUYbZZweZ0jHrozA2d7eEC+c=; b=EPW3hX0CHvyETxVQ+oZKb2FjUUWU1c6cS30QrikW+VmFz1wBFlbSlKVUeXjGw2U+864x01 jpK6IoTPuN1gR5ftY4QdElRbV2wI/xy4Lxupa69QEUDRWtVTmxGEsJzk3tn3A+/Ibyeagu Sioj6pFN6/sJP4frdYjP14ZOKNjwChk= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 72744ACAF; Tue, 5 Jan 2021 07:50:29 +0000 (UTC) Date: Tue, 5 Jan 2021 08:50:28 +0100 From: Michal Hocko To: Dan Williams Cc: David Hildenbrand , Linux MM , LKML Subject: Re: uninitialized pmem struct pages Message-ID: <20210105075028.GS13207@dhcp22.suse.cz> References: <20210104100323.GC13207@dhcp22.suse.cz> <033e1cd6-9762-5de6-3e88-47d3038fda7f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 04-01-21 21:17:43, Dan Williams wrote: > On Mon, Jan 4, 2021 at 2:45 AM David Hildenbrand wrote: [...] > > I believe Dan mentioned somewhere that he wants to see a real instance > > of this producing a BUG before actually moving forward with a fix. I > > might be wrong. > > I think I'm missing an argument for the user-visible effects of the > "Bad." statements above. I think soft_offline_page() is a candidate > for a local fix because mm/memory-failure.c already has a significant > amount of page-type specific knowledge. So teaching it "yes" for > MEMORY_DEVICE_PRIVATE-ZONE_DEVICE and "no" for other ZONE_DEVICE seems > ok to me. I believe we do not want to teach _every_ pfn walker about zone device pages. This would be quite error prone. Especially when a missig check could lead to a silently broken data or BUG_ON with debugging enabled (which is not the case for many production users). Or are we talking about different bugs here? -- Michal Hocko SUSE Labs