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Wed, 04 Nov 2026 04:29:44 -0800 (PST) Message-ID: Date: Wed, 4 Nov 2026 13:29:43 +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 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> <70686061-787c-4c99-ba5b-ff982c8cc2ad@gmail.com> <2vxzfqxglrg6.fsf@kernel.org> Content-Language: en-US From: "Jose A. Perez de Azpillaga" In-Reply-To: <2vxzfqxglrg6.fsf@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: F08A91C0007 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-Stat-Signature: oap1qk3a7jhe894yciggu9ptyurgzyz8 X-Rspam-User: X-HE-Tag: 1793795390-298474 X-HE-Meta: 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 eJRjOp6a CegllN9Kl4RADjICdLl/AeYb3VqUdhcKfAMfXe6P37t+jI90QJqY8MVz0wbMSQ5+8bSDsJnIf6aDrZvW4gOIEGOM4Y2wqRx3/LKfFKdmpkRIYDwZO5sBW0pTx55onGRicrnxUeQuzuBNPfUWQ8VkIdTbxUSmzHWDWSjpB2Cx40ShvJFl0IfdVVOJqz8jL9jCRxUEXf+AP62bUI8T7gMCZVpu+prZSDQomlsyVPA4SUe186cIyq9JoLOHljG90qg4VceG/bRaLzk6DvPVuCIg6k6z10u06lgitTcTsX1lHTtKsfeOy2y8GmwNP4p0LIJxi40hh3ag+p3NtmijICGzqmDS3q7tK7i8e/9409Wm99wfUg3wGQYPr9nscj4CxfHLQ+gAgid5hX/KtpJiFxWtTa1Q3RU036ebLeaDrvlSlzoo8Xw4hQ9iWTZ0s7aluiYrsW8mpUHpkhB925qsfmsn2/q1tA+cKTsbszDPSNuh8raLG/7c= 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 11/4/26 1:19 PM, Pratyush Yadav wrote: > On Wed, Nov 04 2026, Jose A. Perez de Azpillaga wrote: > >> 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 there was a use case, I wouldn't mind fixing it. But I'd rather not > add code we don't have a use case for. > >>> >>> 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? > > This sounds good I think. > okay, I'll drop 1/2 and send that as v2 :) -- cheers, jose a. p-a