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Thu, 22 Oct 2026 13:16:02 -0700 (PDT) Message-ID: <32dd1f28-db55-4674-99bc-74d9d3ab25db@gmail.com> Date: Thu, 22 Oct 2026 22:16:01 +0200 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 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> Content-Language: en-US From: "Jose A. Perez de Azpillaga" In-Reply-To: <2vxzqzhhg8l3.fsf@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D3B8812000D X-Stat-Signature: 5apc6wfyspiz1jiwew5yk3qj8514s6wn 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-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1792700164-844727 X-HE-Meta: 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 jvzotHrS 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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 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? -- cheers, jose a. p-a