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AJvYcCX0aZq/pQDwkmoA9pFQ5/xfH7Y0DcfTaDAHK/zagdaO6sR3bwThf1uL8rczhSXOSzhnx8tJjqvIwg==@kvack.org X-Gm-Message-State: AOJu0Ywihx8H187GnpupCceyYXgCuoRMilSrOCUzgRK8fuV8s9imnJql clRF0EqjJpXE1yzhNhqz58VzSSbkswDIkTURBnogB+Zew2bBRLEDYwMSNy9PaLi/rpnnSWY9gZY MI7zpdN1zpARm29VahTz6SloOOT+rb5eEQeSafQ== X-Gm-Gg: ASbGncv1Szq8qYzpaUf9g2FumeSNcoX9U/+bZWNHJNmFh/pirQ+UpOLbWnb41s0DIOl c3c95ErfpoGV+k/WZDSkr2L7HGyO+CYzC53GRNQitZrgdmIY6eNTOgUnDsTNCVx66Ve21HUh4f2 TPqdUdp+XVbzyY0oVI4Ee4VlOc X-Google-Smtp-Source: AGHT+IGc+rzcOSqRq1NAurG0wArv+f9TNDXi3NJHkDUdzPbqAqbmujaqTIOq09aOpi8XwtONse7qgR0mbQ4HEgDxOjc= X-Received: by 2002:ac8:529a:0:b0:477:29f5:53eb with SMTP id d75a77b69052e-47729f55467mr169156461cf.6.1742912430244; Tue, 25 Mar 2025 07:20:30 -0700 (PDT) MIME-Version: 1.0 References: <20250320015551.2157511-1-changyuanl@google.com> In-Reply-To: <20250320015551.2157511-1-changyuanl@google.com> From: Pasha Tatashin Date: Tue, 25 Mar 2025 10:19:53 -0400 X-Gm-Features: AQ5f1JpBD7J0LGV4vivBPILeYhry8D0ETPzHZusd7bV5-E3dLFdBAyFaK8Fs_Bw Message-ID: Subject: Re: [PATCH v5 00/16] kexec: introduce Kexec HandOver (KHO) To: Changyuan Lyu Cc: linux-kernel@vger.kernel.org, graf@amazon.com, akpm@linux-foundation.org, luto@kernel.org, anthony.yznaga@oracle.com, arnd@arndb.de, ashish.kalra@amd.com, benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com, dave.hansen@linux.intel.com, dwmw2@infradead.org, ebiederm@xmission.com, mingo@redhat.com, jgowans@amazon.com, corbet@lwn.net, krzk@kernel.org, rppt@kernel.org, mark.rutland@arm.com, pbonzini@redhat.com, hpa@zytor.com, peterz@infradead.org, ptyadav@amazon.de, robh+dt@kernel.org, robh@kernel.org, saravanak@google.com, skinsburskii@linux.microsoft.com, rostedt@goodmis.org, tglx@linutronix.de, thomas.lendacky@amd.com, usama.arif@bytedance.com, will@kernel.org, devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 4FAF740012 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: 49tf6i1qr5k3ra4ga3uxdjxcwdr6euf4 X-HE-Tag: 1742912431-614931 X-HE-Meta: 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 t6a4uGgn Vrj7lerPDqKie5QONw2MufTqEilRRyi9LH/EWuyS0KqRDaj6RVWGRFq+7YlDCdCH55aedRVfOAAlQd7aOqragnNRM2m7I6zEdIXM15nTzgmqKlonlXObjaDH6FJ/RKRLoZSY6wLIRQW0EF0PuuKmpiXsXy6sYGvNuLJjaa8knTzWfOXNf1jWcsJSeMWkDVm44N03VeUp7uETBrXJ4X4aB9CwDxYGCBQvkl4d2oHEt62pbWBLGrncZCxlX27++cmny5W9D7uw6tFdQ8bjrKsbxtQDuYGMLes+S4f6VzrjDc7CUWwMmozS0V3hQArcO4o5vJhnDsIjFo0IHG6TFKulWuVKqnLseOyAqkdPf X-Bogosity: Ham, tests=bogofilter, spamicity=0.000053, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > To use the code, please boot the kernel with the "kho=on" command line > parameter. > KHO will automatically create scratch regions. If you want to set the > scratch size explicitly you can use "kho_scratch=" command line parameter. > For instance, "kho_scratch=16M,512M,256M" will reserve a 16 MiB low > memory scratch area, a 512 MiB global scratch region, and 256 MiB > per NUMA node scratch regions on boot. kho_scratch= is confusing. It should be renamed to what this memory actually represents, which is memory that cannot be preserved by KHO. I suggest renaming all references to "scratch" and this parameter to: kho_nopersistent= or kho_nopreserve= This way, we can also add checks that early allocations done by the kernel in this memory do not get preserved. We can also add checks to ensure that scarce low DMA memory does not get preserved across reboots, and we avoid adding fragmentation to that region. Pasha