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Perez de Azpillaga" Cc: Pratyush Yadav , 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 Subject: Re: [RFC PATCH 0/2] memblock: keep reserve_mem regions out of KHO bootmem In-Reply-To: <70686061-787c-4c99-ba5b-ff982c8cc2ad@gmail.com> (Jose A. Perez de Azpillaga's message of "Wed, 4 Nov 2026 11:50:02 +0100") 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> Date: Wed, 04 Nov 2026 13:19:21 +0100 Message-ID: <2vxzfqxglrg6.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 020C5140009 X-Stat-Signature: 9t4p6zfo1zrhrd4juo3c6sh6qp1en3oe X-Rspam-User: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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: 1793794765-990917 X-HE-Meta: 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 ypQLbH/Z eGHbj4lpcTWFi3qk8dd0PUzXXfVsTUlIH3G+5aT7CYUuOwm6w9eOotctyvIrE7Y1g/y4dVGwG9IY24zCshRWeBg9Gz6f0yECShGokGUaPszoO8+jgXOPt8ynWLMG5F1e6RNJ10/G3SyCG4M0lLOoYMNDRfxK1l0yZbin84jEe3elSwpSrH08LbUxVoBz4dUGSu0BtDYLJC/6mslJHWh1bX6NeBXGH5GuVSe/h7QyGcPyyyn5s+vRo3Kb12IAmO9Eu6nRM 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 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. >> > > ping, I can send a v2 either way. -- Regards, Pratyush Yadav