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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DB791C982F1 for ; Tue, 22 Sep 2026 10:39:58 +0000 (UTC) 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-Owner; bh=zkVHXvH6aSNeIiHZsZBLuLPhi5KT7D0PnrCA/uC+Aww=; b=3PlUK9e2qu68r81oYgPTCdSNCi 2OGY0SPljVnUuaDzMd1qXseRxXtHMN8j4ef8HA9nrblGOS6bxN2zfGqKNx80oV4geHGKhInlRsJ52 XZ9ulhKELxhkA+wzsmVPjSUnmzCckyejfpBRlfZVOT+G0wo+mQ+lfNASDKvkVNeL8VUStKENerGYN ZWXdIEYyK0DXi/YakDtg3OzmYzxbUIrMkXNlFYDAc7Y517Vh05GL+0bucB4X6awMchz/qRlR8pG6A YRXRs21MD4bXt3p6rY/C45yKj5KBnrRf4321L5FvVUAuQcOt1MsBBjiAMamjO+l76PYx8QCoyJLhk sBVBBKqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8xun-0000000556K-28YU; Tue, 22 Sep 2026 10:39:57 +0000 Received: from stravinsky.debian.org ([2001:41b8:202:deb::311:108]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8xul-0000000555b-2Jko for kexec@lists.infradead.org; Tue, 22 Sep 2026 10:39:56 +0000 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=zkVHXvH6aSNeIiHZsZBLuLPhi5KT7D0PnrCA/uC+Aww=; b=LAJ1KE5fYZ3ToH2JjALIy5lMHl M59CT9fHAa0I8HqTqLbRMlnd8o7XvcrxwQXQ6N5/lNLK5KUBcpIkeqh5xwIsQsCF8VO1QMRu2Z/0q WX+cDPCgXBS6yzxPgKsUAXJ0sShUnGzJiy6uHMD+mA/E5U1zQp+MF/MwH588ohKVp40f7XrAV2D2r z1o1STvQfbXYwaW89gLnyAarb1UbHwFj8HQdGkcs8ImImluh0IcAEH/0XjoV5I4CAYQqIEMmP7z7F AKvnZhso8fTnU9daXknVjmAVBb5oTTAjvQ1/ZcIqnO/MulZ1ik0pzxnwUI7OU0bnQvnGja5vlJkgA aihXbVZA==; 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 1x8xuL-002vHv-1e; Tue, 22 Sep 2026 10:39:29 +0000 Date: Tue, 22 Sep 2026 03:39:21 -0700 From: Breno Leitao To: Miaohe Lin Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rmikey@meta.com, riel@surriel.com, harry@kernel.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, kernel-team@meta.com, Ard Biesheuvel , Ilias Apalodimas , Naoya Horiguchi , Andrew Morton , kas@kernel.org, kexec@lists.infradead.org, David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Brendan Jackman , Johannes Weiner , Zi Yan , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , hannes@cmpxchg.or, shakeel.butt@linux.dev Subject: Re: [PATCH v5 0/9] mm/memory-failure: keep hardware-poisoned pages out of the next kexec Message-ID: References: <20260915-hwpoison-kho-v5-0-3bc7a57bd503@debian.org> <16baab50-692c-308b-d60d-1b0a328df1e3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16baab50-692c-308b-d60d-1b0a328df1e3@huawei.com> X-Debian-User: leitao X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_033955_595393_03BE8805 X-CRM114-Status: GOOD ( 21.92 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, Sep 22, 2026 at 05:29:14PM +0800, Miaohe Lin wrote: > On 2026/9/22 17:14, Breno Leitao wrote: > > Hello Miaohe, > > > > On Tue, Sep 22, 2026 at 02:27:59PM +0800, Miaohe Lin wrote: > >>> A bit is never cleared, which is a known limitation: it stands for a > >>> whole unit, so an unpoison of one frame cannot tell whether the unit as a > >>> whole is good again. > >> > >> Thanks for your patches. I have a question about unpoison: If a bit is never > >> cleared, after we do some memory-failure+unpoison tests, kexec will lose the > >> tested memory without reboot? > > > > Correct, A bit stands for a 2M unit, so every tested page that falls in > > a distinct unit costs 2M in each kernel after the kexec. > > > > Worth being precise about the state today: the unpoison itself works. > > The frame goes back to the allocator and num_poisoned_pages drops. Only > > the bit stays, so the next kernel poisons the frame again. Test loop > > in, memory out, and nothing gives it back. > > > > Important to say that nothing block us from unpoison the bitmap, and in > > fact my initial patchset had it. I also _think_ we should unpoison the > > bitmap once we unpoison the page. > > > > I have just kept it out of this patch in order to simplify the patchset and > > get the basis correct, and then evolve on top of it. > > > > Makes sense to me. Thanks for your work. Ack. I will continue it without the unpoisioned bits for now, and as soon as this series lands, I will add the unpoision mechanism on top of this infrastructure. Thanks for your support so far. I will send a new version soon, with the fixes I am accumulating so far. --breno