From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:39448 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726690AbfFEI6u (ORCPT ); Wed, 5 Jun 2019 04:58:50 -0400 Subject: Re: [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory() References: <20190527111152.16324-1-david@redhat.com> <20190527111152.16324-8-david@redhat.com> <20190604214234.ltwtkcdoju2gxisx@master> From: David Hildenbrand Message-ID: Date: Wed, 5 Jun 2019 10:58:26 +0200 MIME-Version: 1.0 In-Reply-To: <20190604214234.ltwtkcdoju2gxisx@master> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Wei Yang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, Dan Williams , Igor Mammedov , Greg Kroah-Hartman , "Rafael J. Wysocki" , "mike.travis@hpe.com" , Ingo Molnar , Andrew Banman , Oscar Salvador , Michal Hocko , Pavel Tatashin , Qian Cai , Arun KS , Mathieu Malaterre >> /* >> * For now, we have a linear search to go find the appropriate >> * memory_block corresponding to a particular phys_index. If >> @@ -658,6 +670,11 @@ static int init_memory_block(struct memory_block **memory, int block_id, >> unsigned long start_pfn; >> int ret = 0; >> >> + mem = find_memory_block_by_id(block_id, NULL); >> + if (mem) { >> + put_device(&mem->dev); >> + return -EEXIST; >> + } > > find_memory_block_by_id() is not that close to the main idea in this patch. > Would it be better to split this part? I played with that but didn't like the temporary results (e.g. having to export find_memory_block_by_id()). I'll stick to this for now. > >> mem = kzalloc(sizeof(*mem), GFP_KERNEL); >> if (!mem) >> return -ENOMEM; >> @@ -699,44 +716,53 @@ static int add_memory_block(int base_section_nr) >> return 0; >> } >> >> +static void unregister_memory(struct memory_block *memory) >> +{ >> + if (WARN_ON_ONCE(memory->dev.bus != &memory_subsys)) >> + return; >> + >> + /* drop the ref. we got via find_memory_block() */ >> + put_device(&memory->dev); >> + device_unregister(&memory->dev); >> +} >> + >> /* >> - * need an interface for the VM to add new memory regions, >> - * but without onlining it. >> + * Create memory block devices for the given memory area. Start and size >> + * have to be aligned to memory block granularity. Memory block devices >> + * will be initialized as offline. >> */ >> -int hotplug_memory_register(int nid, struct mem_section *section) >> +int create_memory_block_devices(unsigned long start, unsigned long size) >> { >> - int block_id = base_memory_block_id(__section_nr(section)); >> - int ret = 0; >> + const int start_block_id = pfn_to_block_id(PFN_DOWN(start)); >> + int end_block_id = pfn_to_block_id(PFN_DOWN(start + size)); >> struct memory_block *mem; >> + unsigned long block_id; >> + int ret = 0; >> >> - mutex_lock(&mem_sysfs_mutex); >> + if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) || >> + !IS_ALIGNED(size, memory_block_size_bytes()))) >> + return -EINVAL; >> >> - mem = find_memory_block(section); >> - if (mem) { >> - mem->section_count++; >> - put_device(&mem->dev); >> - } else { >> + mutex_lock(&mem_sysfs_mutex); >> + for (block_id = start_block_id; block_id != end_block_id; block_id++) { >> ret = init_memory_block(&mem, block_id, MEM_OFFLINE); >> if (ret) >> - goto out; >> - mem->section_count++; >> + break; >> + mem->section_count = sections_per_block; >> + } >> + if (ret) { >> + end_block_id = block_id; >> + for (block_id = start_block_id; block_id != end_block_id; >> + block_id++) { >> + mem = find_memory_block_by_id(block_id, NULL); >> + mem->section_count = 0; >> + unregister_memory(mem); >> + } >> } > > Would it be better to do this in reverse order? > > And unregister_memory() would free mem, so it is still necessary to set > section_count to 0? 1. I kept the existing behavior (setting it to 0) for now. I am planning to eventually remove the section count completely (it could be beneficial to detect removing of partially populated memory blocks). 2. Reverse order: We would have to start with "block_id - 1", I don't like that better. Thanks for having a look! -- Thanks, David / dhildenb