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X-CSE-ConnectionGUID: U44caBqrSvqnPI9JgxVuNA== X-CSE-MsgGUID: ULwR3TV0T9ulZCB00Iq/HQ== X-IronPort-AV: E=McAfee;i="6800,10657,11886"; a="90742688" X-IronPort-AV: E=Sophos;i="6.25,244,1779174000"; d="scan'208";a="90742688" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2026 06:33:23 -0700 X-CSE-ConnectionGUID: fi5T9AQgRHK+SFB76qGiag== X-CSE-MsgGUID: ySqgx6cOTpOE0EdGdDI7Yw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,244,1779174000"; d="scan'208";a="305804799" Received: from rchatre-mobl4.amr.corp.intel.com (HELO [10.125.109.37]) ([10.125.109.37]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2026 06:33:24 -0700 Message-ID: <33cf028a-58c7-4ffd-af80-d689a67684c7@intel.com> Date: Wed, 26 Aug 2026 06:33:23 -0700 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 v3 1/2] x86/crash: reserve elfcorehdr for CONFIG_NR_CPUS, not CONFIG_NR_CPUS_DEFAULT To: "Ionut Nechita (Wind River)" , x86@kernel.org, kexec@lists.infradead.org Cc: tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, eric.devolder@oracle.com, hbathini@linux.ibm.com, sourabhjain@linux.ibm.com, ruanjinjie@huawei.com, include@grrlz.net, linux-kernel@vger.kernel.org References: <20260826073527.21487-1-ionut.nechita@windriver.com> <20260826073527.21487-2-ionut.nechita@windriver.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/26/26 00:35, Ionut Nechita (Wind River) wrote: > Assisted-by: LLM "LLM" went a little wild on the changelogs here. Shouldn't this just be something like: NR_CPUS_DEFAULT is *purely* a Kconfig thing. Its entire purpose in life is to start NR_CPUS at a sane value. There is precisely one (buggy) reference to it outside of Kconfig in the whole kernel: the x86 crash code. That code will undersize a reservation if NR_CPUS exceeds NR_CPUS_DEFAULT. This causes kexec_load() silently truncate the elfcorehdr, which surfaces later as a bad or unusable dump. Size the elfcorehdr reservation with NR_CPUS instead. --- Does it need more than that?