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b=sVk/USQ64Orrpyfz0mu6ZUa1S1fjZPZtMuDdj5fmZEMCViOctL4J3ASH0iOMb2pJG PkI9LlbNvQz3AuBcYuaVkeh+7rshP+zapdg3gsvXV5S4ViHwAssXWmuYHFshZWRDNJ Nh7RST06ST8IGkG2M0bgQC4JVFHbVztyjtK2ha0bNdb6xffvqcEf+j/Aa6BgqHvfeX eSgxvppJpPiEaO19+AQ/DK6oDxXIpSZcPejCzf0KpfFS26wxcIlb1HVmpCuJrSgBHU LzDa4lk70qAkQ6u1elXClbFjDLIjqGSljol4fZdbDX69nMKSpv3VfvHlpx2R8lump/ FGOeDCGS+G1mg== Date: Mon, 1 Dec 2025 08:50:24 +0200 From: Mike Rapoport To: Swaraj Gaikwad Cc: akpm@linux-foundation.org, david.hunter.linux@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, skhan@linuxfoundation.org Subject: Re: [PATCH RFC] mm/memblock: Fix reserve_mem allocation overlapping KHO scratch regions Message-ID: References: <20251130211540.582343-1-swarajgaikwad1925@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20251130211540.582343-1-swarajgaikwad1925@gmail.com> X-Rspamd-Queue-Id: D430DA0006 X-Rspamd-Server: rspam06 X-Rspam-User: X-Stat-Signature: d1qe1eyxeoj8jea4ft6z77fsjzdym5ec X-HE-Tag: 1764571831-383849 X-HE-Meta: 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 2X/kLXjX bTTDtlqFA4wHZlXHDSVrWc+gwLEA06f2w6NmVB7Uwqq1LmihZ+e5sbAYc82RymDko0pQ9csaloSBJ2rTOkxuuX3JjksR6xZ5dwWPh1mHk/RBc10VrU5baWAd+yIOlBt2RJ4JaXkQKadbdrDtIO95PiEKGkLL6iaQ1sGfbAoOhBZknPkF11inNNt31ogSB7ih5NojSqgzDPN89PvHph9No6XUKRtb/XgMAYlTqlSU3WjWNzdPctoDwBgVf06hc7bvu47X9pBPO3ClK38XVc2WbKhlbcZVOIhEzVl9Q6jbEnqtTxBFjRgbifYSB7nHCQEjkXfrisGFmxK0ar0TJf4JMWswS0MtxfEB7AkE48uITVCueiIQAHhikDvWt/FIJpcC4ONRJ/VibK1m+LqU5rj92hHC2Sv0lVjgEDkJtElBpeNLdAZw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Swaraj, On Sun, Nov 30, 2025 at 09:15:39PM +0000, Swaraj Gaikwad wrote: > Hi Mike, > > Thanks for the feedback. > > This patch was sent as an RFC because I wanted to confirm whether the > overall approach is acceptable before preparing a fully tested version. > I will send a properly tested patch once I get confirmation that this > direction makes sense. I didn't look into the details, but I think what you propose won't work. The first kernel allocates KHO scratch after parsing reserve_mem and the second kernel allocates everything from KHO scratch at the time early_params are parsed. > I’m reviewing how reserve_mem= paths are exercised so I can build an > appropriate test setup. Any guidance on recommended testing for this > area is appreciated. In general to test changes to memblock and other early code I use qemu and some scripts around it. > Thanks, > Swaraj -- Sincerely yours, Mike.