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X-CSE-ConnectionGUID: UsCEKvgVTnKqGSZB7kpFyw== X-CSE-MsgGUID: Xv2ufnejQZaJhZEF4ySadg== X-IronPort-AV: E=McAfee;i="6700,10204,11179"; a="41053122" X-IronPort-AV: E=Sophos;i="6.10,185,1719903600"; d="scan'208";a="41053122" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Aug 2024 08:18:10 -0700 X-CSE-ConnectionGUID: GhudT9hHSPW/RRNvBRcbkA== X-CSE-MsgGUID: 8dwgPF14R46vsYE7nUuLuw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,185,1719903600"; d="scan'208";a="94349706" Received: from tfalcon-desk.amr.corp.intel.com (HELO [10.124.220.59]) ([10.124.220.59]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Aug 2024 08:18:10 -0700 Message-ID: Date: Thu, 29 Aug 2024 08:17:53 -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] x86/sgx: Fix deadloop in __sgx_alloc_epc_page() To: Aaron Lu , Jarkko Sakkinen , Dave Hansen Cc: x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, Zhimin Luo References: <20240829023800.1671210-1-aaron.lu@intel.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 Generally, I think it's a bad idea to refer to function names in subjects. This, for instance would be much more informative: x86/sgx: Fix deadlock in SGX NUMA node search On 8/28/24 19:38, Aaron Lu wrote: > When current node doesn't have a EPC section configured by firmware and > all other EPC sections memory are used up, CPU can stuck inside the > while loop in __sgx_alloc_epc_page() forever and soft lockup will happen. > Note how nid_of_current will never equal to nid in that while loop because > nid_of_current is not set in sgx_numa_mask. > > Also worth mentioning is that it's perfectly fine for firmware to not > seup an EPC section on a node. Setting an EPC section on each node can > be good for performance but that's not a requirement functionality wise. The changelog is a little rough, but I think Kai gave some good suggestions. The other thing you can do is dump the text in chatgpt (or whatever) and have it fix your grammar. It actually does a pretty decent job. Also, you didn't say _how_ you fixed this. That needs to be in here. Something along the lines of: Rework the loop to start and end on *a* node that has SGX memory. This avoids the deadlock looking for the current SGX- lacking node to show up in the loop when it never will. The code looks fine, so feel free to add: Acked-by: Dave Hansen Also, I do think we should probably add some kind of sanity warning to the SGX code in another patch. If a node on an SGX system has CPUs and memory, it's very likely it will also have some EPC. It can be something soft like a pr_info(), but I think it would be nice to have.