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Wed, 26 Mar 2025 05:09:34 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFOuyfQGVOhYyFSi3hsb9kc2zJRzczpD7XPzwNdnwVuHyYQPBafKpH087OtVwDsIyzVWltmG166ADE4aJfipJU= X-Received: by 2002:a05:6e02:3a0c:b0:3d4:6f37:372c with SMTP id e9e14a558f8ab-3d5960e2419mr225831915ab.7.1742990973998; Wed, 26 Mar 2025 05:09:33 -0700 (PDT) MIME-Version: 1.0 References: <20250320015551.2157511-1-changyuanl@google.com> <20250320015551.2157511-12-changyuanl@google.com> In-Reply-To: From: Dave Young Date: Wed, 26 Mar 2025 20:09:55 +0800 X-Gm-Features: AQ5f1JrnxWyTc7ruwIDaX1fnmt0FdUmOV-OtIvcwHa3Skex-wO_kM_31tXed_lg Message-ID: Subject: Re: [PATCH v5 11/16] kexec: add config option for KHO To: Mike Rapoport Cc: Baoquan He , Changyuan Lyu , 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, mark.rutland@arm.com, pbonzini@redhat.com, pasha.tatashin@soleen.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 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: pH4hlWmNPn3p9LmaFLpdwgyabiIr5Th-UFMq4fpo1s4_1742990975 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: A37D318001B X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: o8xqpojy6oqwxbj7smk7yufn7xma89ju X-HE-Tag: 1742990977-984985 X-HE-Meta: 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 X9BvWEzL NK5383J9Xi/2oMZVh8NlYGajRWr773Qdy7LQWl9SqgjEV4bUss/u0iJREKWOEX8djOuZuE1UsAr5iILyX3MHKnjqwAFD6yfMPsJLejeaqdfmYEwJZ+nUCc6y0QvQz8EEGQEXnvNpEqIzCFNgB4ljKrgaaee4mJzoLkfMI X-Bogosity: Ham, tests=bogofilter, spamicity=0.000985, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 26 Mar 2025 at 19:34, Mike Rapoport wrote: > > Hi Dave, > > On Wed, Mar 26, 2025 at 05:17:16PM +0800, Dave Young wrote: > > On Tue, 25 Mar 2025 at 16:36, Dave Young wrote: > > > > > > > > > > > > > Have you tested kdump? In my mind there are two issues, one is with > > > > > CMA enabled, it could cause kdump crashkernel memory reservation > > > > > failures more often due to the fragmented low memory. Secondly, in > > > > > > > > kho scracth memorys are reserved much later than crashkernel, we may not > > > > need to worry about it. > > > > ==================== > > > > start_kernel() > > > > ...... > > > > -->setup_arch(&command_line); > > > > -->arch_reserve_crashkernel(); > > > > ...... > > > > -->mm_core_init(); > > > > -->kho_memory_init(); > > > > > > > > > kdump kernel dump the crazy scratch memory in vmcore is not very > > > > > meaningful. Otherwise I suspect this is not tested under kdump. If > > > > > so please disable this option for kdump. > > > > > > Ok, it is fine if this is the case, thanks Baoquan for clearing this worry. > > > > > > But the other concerns are still need to address, eg. KHO use cases > > > are not good for kdump. > > > There could be more to think about. > > > eg. the issues talked in thread: > > > https://lore.kernel.org/lkml/Z7dc9Cd8KX3b_brB@dwarf.suse.cz/T/ > > > > Rethink about this, other than previous concerns. Transferring the > > old kernel state to kdump kernel makes no sense since the old state is > > not stable as the kernel has crashed. > > KHO won't be active for kdump case. The KHO segments are only added to > kexec_image and never to kexec_crash_image. Good to know, thanks! > > -- > Sincerely yours, > Mike. >