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([2a02:6b6f:e750:1800:450:cba3:aec3:a1fd]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4790ade12cesm51865185e9.9.2025.11.26.03.43.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Nov 2025 03:43:22 -0800 (PST) Message-ID: Date: Wed, 26 Nov 2025 11:43:21 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/memblock: only mark/clear KHO scratch memory when needed Content-Language: en-GB To: Kiryl Shutsemau , rppt@kernel.org Cc: Andrew Morton , changyuanl@google.com, graf@amazon.com, leitao@debian.org, thevlad@meta.com, pratyush@kernel.org, dave.hansen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20251126072051.546700-1-usamaarif642@gmail.com> From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 26/11/2025 10:40, Kiryl Shutsemau wrote: > On Wed, Nov 26, 2025 at 07:20:51AM +0000, Usama Arif wrote: >> @@ -1126,8 +1126,11 @@ int __init_memblock memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t >> */ >> __init int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size) >> { >> - return memblock_setclr_flag(&memblock.memory, base, size, 1, >> - MEMBLOCK_KHO_SCRATCH); >> + if (IS_ENABLED(CONFIG_MEMBLOCK_KHO_SCRATCH) && is_kho_boot()) > > It makes me wounder why CONFIG_MEMBLOCK_KHO_SCRATCH exists? It seems to > be a proxy for CONFIG_KEXEC_HANDOVER which is the only option that > selects it and does it always. > > Can we make s/CONFIG_MEMBLOCK_KHO_SCRATCH/CONFIG_KEXEC_HANDOVER/ and > remove IS_ENABLED() from this check? Just is_kho_boot() is enough. > > Thats a very good point! I imagine it might have been for maybe debug purposes? Looking at the code, CONFIG_MEMBLOCK_KHO_SCRATCH shouldnt be needed. I guess this might be a good time to clean it up. If Mike is happy for it to be replaced with CONFIG_KEXEC_HANDOVER (and removed where needed), happy to send that for review instead of this. Thanks Usama