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Wed, 04 Nov 2026 02:50:05 -0800 (PST) Received: from [192.168.1.22] ([83.231.69.9]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b2a555e59dsm145066805e9.0.2026.11.04.02.50.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Nov 2026 02:50:04 -0800 (PST) Message-ID: <70686061-787c-4c99-ba5b-ff982c8cc2ad@gmail.com> Date: Wed, 4 Nov 2026 11:50:02 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/2] memblock: keep reserve_mem regions out of KHO bootmem From: "Jose A. Perez de Azpillaga" To: Pratyush Yadav Cc: Mike Rapoport , Andrew Morton , Kees Cook , Alexander Graf , Changyuan Lyu , Tony Luck , "Guilherme G. Piccoli" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pasha Tatashin , kexec@lists.infradead.org References: <20261021211058.83483-1-azpijr@gmail.com> <2vxzqzhhg8l3.fsf@kernel.org> <32dd1f28-db55-4674-99bc-74d9d3ab25db@gmail.com> Content-Language: en-US In-Reply-To: <32dd1f28-db55-4674-99bc-74d9d3ab25db@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: ee4tbpsr6mtpcea5irrzpexc984ak66r X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 89DBAC0004 X-Spam-Status: No, score=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793789407-453540 X-HE-Meta: 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 UuSTIqCs 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/22/26 10:16 PM, Jose A. Perez de Azpillaga wrote: > On 10/22/26 3:37 PM, Pratyush Yadav wrote: >> On Wed, Oct 21 2026, Jose A. Perez de Azpillaga wrote: >> >>> On a KHO boot, a reserve_mem= region that can't be revived (new name, >>> size or alignment) can be allocated from KHO bootmem, which the next >>> kernel boots out of. With CONFIG_KEXEC_HANDOVER_DEBUG preserving it >>> fails; without it, the next kernel's memmap ends up on top of it. >> What's your use-case? Why are you adding new reserve_mem regions after >> cold boot? I'd rather avoid making purely theoretical fixes. > > I don't have one, I found it through the TODO. a different reserve_mem= > in the cmdline passed to kexec is enough to hit it. > > if it isn't meant to work across a live update, would you rather have > reserve_mem() fail on KHO boot when it can't revive the region? > ping, I can send a v2 either way. -- cheers, jose a. p-a