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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 1wxSLG-00BTcG-28; Fri, 21 Aug 2026 16:43:43 +0000 Date: Fri, 21 Aug 2026 09:43:37 -0700 From: Breno Leitao To: Kiryl Shutsemau Cc: Ard Biesheuvel , Ilias Apalodimas , Miaohe Lin , Naoya Horiguchi , Andrew Morton , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rmikey@meta.com, riel@surriel.com, kexec@lists.infradead.org, kernel-team@meta.com Subject: Re: [PATCH v2 6/6] efi: respect the poisoned pages coming from previous kernel Message-ID: References: <20260821-hwpoison-kho-v2-0-5743791e48e6@debian.org> <20260821-hwpoison-kho-v2-6-5743791e48e6@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Debian-User: leitao X-Stat-Signature: pdthqbjrgk46n5ppbzon45w39if9q9t5 X-Rspamd-Queue-Id: 8D1D8C0004 X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1787332893-251006 X-HE-Meta: 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 yM0Sx+ru VoEzxx+5woIHp/JR1erPV5IRYVdp+Hw1lzIDRFdW6z8xx/8VaZudBKqArhTWQqt/xwHtei1954ABsXY2xaAWnHo6xt3JxIApGCa04TDTBZjIPP33UEVH3M4xdnr+4cmssJdTG4kCeaaETZGQDCJzkqjX3XCtm9/OOdDZ8odztm0N51WnlHosrJo4yPUsKexH6Gu2DqgM/6wpEisi8jCQr5dTCHfSeyCEzMkLMvq2J5lwzrXwWpkP4xVHOQbdxKr5gro3NJ4mQlAzbg8p0vz7n1AjaLbicL9FXw/NctDqCwzXPf0yKoKDychDSt6QnBWzjoWMAr4lT4U6g3Dkny2xCslNViDm5re/pkMQho1CQiKhXN3czg3TNguvCLZDoXXijL1dYaJMggVEbdMirIDCPzsnhYg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Aug 21, 2026 at 03:53:32PM +0100, Kiryl Shutsemau wrote: > On Fri, Aug 21, 2026 at 07:03:06AM -0700, Breno Leitao wrote: > > On Fri, Aug 21, 2026 at 01:13:55PM +0100, Kiryl Shutsemau wrote: > > > On Fri, Aug 21, 2026 at 03:06:06AM -0700, Breno Leitao wrote: > > > > + /* Reserve the table itself so it survives a further kexec. */ > > > > + memblock_reserve(PAGE_ALIGN_DOWN(ppm), > > > > + PAGE_ALIGN(ppm + sizeof(*pm) + bitmap_size) - > > > > + PAGE_ALIGN_DOWN(ppm)); > > > > > > Hm. I don't think it is enough. > > > > > > On x86, kernel doesn't keep memblock around after boot (see > > > CONFIG_ARCH_KEEP_MEMBLOCK). Reserving in memblock exclude the memory > > > from page allocator. But kexec can place the image there. > > > > You mean the third kexec? > > > > 1) Kernel A hits an ECC error and marks page X poisoned. > > 2) Kernel A kexecs into kernel B, which won't use that page since > > it's in EFI_POISONED_PAGE and memblock-reserved. > > 3) Kernel B kexecs into kernel C, which doesn't respect > > EFI_POISONED_PAGE. > > > > Is this the scenario you mean? > > No. I think nothing prevents kernel B from putting kernel C image into > the reserved space in !CONFIG_ARCH_KEEP_MEMBLOCK case. > > Kernel B excludes poisoned memory from buddy allocator, but kexec > doesn't care about this when look for placement for the next image. Right, that is exactly the case I meant above — sorry for not being clearer. Agreed, this is a gap. Can we keep it separate for now and address it as a follow-up? Similar to the one covered the initial issue [1] first. Link: https://lore.kernel.org/all/20260812-kexec_posioned-v6-0-e477887086f0@debian.org/ [1]