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b=sSQ68kiIHDplwo1zFk3SzUrE+WrJ3EwXJR/bMMF7djp7u9Ac+d9pSi34Pro2U77PmUsrx1M2PUK3XNnDX36gK7cMys5Z5NPBH1XWnY9HyVtnLJkpFS0xFEGMB47oNW+SU5wNWCwbKlszZVWUKwkikoW1KG3Zudg6Y58fA4gLT+c= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from CH3PR12MB8403.namprd12.prod.outlook.com (2603:10b6:610:133::14) by MN0PR12MB6102.namprd12.prod.outlook.com (2603:10b6:208:3ca::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7292.14; Mon, 12 Feb 2024 19:40:23 +0000 Received: from CH3PR12MB8403.namprd12.prod.outlook.com ([fe80::ea0e:199a:3686:40d4]) by CH3PR12MB8403.namprd12.prod.outlook.com ([fe80::ea0e:199a:3686:40d4%4]) with mapi id 15.20.7292.019; Mon, 12 Feb 2024 19:40:23 +0000 Message-ID: <1cf19ecf-4785-48c9-91ef-4ca3c965f568@amd.com> Date: Mon, 12 Feb 2024 13:40:21 -0600 User-Agent: Mozilla Thunderbird Subject: [PATCH 2/2] x86/MCE: Add command line option to extend MCE Records pool Content-Language: en-US To: "Luck, Tony" , Yazen Ghannam , Borislav Petkov Cc: "Mehta, Sohil" , "x86@kernel.org" , "linux-edac@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Avadhut Naik References: <20240207225632.159276-1-avadhut.naik@amd.com> <20240207225632.159276-3-avadhut.naik@amd.com> <8b4f8ec2-7534-4f77-b44f-6728c699ff64@intel.com> <51255499-0b5d-45c6-9c72-f353bae83c0d@amd.com> <20240209200920.GFZcaGcOr757W9O3IG@fat_crate.local> <7a4945b0-322a-444e-a0ca-860a062a49c3@amd.com> <20240209205111.GGZcaQP1gb6C9m0WZB@fat_crate.local> <5DB0FF8D-C6DA-45DC-B287-201A9BF48BDA@alien8.de> <75ddf61d-8dda-47fa-9da0-24221feb22a2@amd.com> <20240211111455.GAZcisL09LeFPWa2EI@fat_crate.local> From: "Naik, Avadhut" In-Reply-To: Content-Type: text/plain; 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> list_add_rcu(&chunk->next_chunk, &pool->chunks); > spin_unlock(&pool->lock); > Even I am somewhat confused by this. The spinlock is mostly held to prevent other primitives from modifying chunks within the genpool. In #MC context however, we are not modifying the existing chunks, per se. While in the MC context, records will be added to the genpool through gen_pool_alloc() which eventually drops down into gen_pool_alloc_algo_owner(). gen_pool_alloc_algo_owner() iterates over the existing chunks within the genpool through list_for_each_entry_rcu(), within an RCU read-side critical section (rcu_read_lock()). Now, the below description of list_for_each_entry_rcu(): * list_for_each_entry_rcu - iterate over rcu list of given type * @pos: the type * to use as a loop cursor. * @head: the head for your list. * @member: the name of the list_head within the struct. * @cond: optional lockdep expression if called from non-RCU protection. * * This list-traversal primitive may safely run concurrently with * the _rcu list-mutation primitives such as list_add_rcu() * as long as the traversal is guarded by rcu_read_lock(). Makes me wonder if the genpool can be extended and traversed concurrently. OFC, not sure if gen_pool_alloc_algo_owner() being in #MC context makes a difference here or if I am missing something. -- Thanks, Avadhut Naik > -Tony > > > >