From: David Hildenbrand <david@redhat.com>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: linux-s390@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
linux-ia64@vger.kernel.org,
Pavel Tatashin <pasha.tatashin@soleen.com>,
linux-sh@vger.kernel.org,
"mike.travis@hpe.com" <mike.travis@hpe.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Mathieu Malaterre <malat@debian.org>,
linux-kernel@vger.kernel.org, Arun KS <arunks@codeaurora.org>,
Ingo Molnar <mingo@kernel.org>,
linux-mm@kvack.org, Andrew Banman <andrew.banman@hpe.com>,
Qian Cai <cai@lca.pw>, Igor Mammedov <imammedo@redhat.com>,
akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org,
Dan Williams <dan.j.williams@intel.com>,
linux-arm-kernel@lists.infradead.org,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory()
Date: Wed, 5 Jun 2019 23:50:52 +0200 [thread overview]
Message-ID: <4d29c1d6-d394-903d-28ae-733d55ac06f4@redhat.com> (raw)
In-Reply-To: <20190605212249.s7knac6vimealdmx@master>
On 05.06.19 23:22, Wei Yang wrote:
> On Wed, Jun 05, 2019 at 12:58:46PM +0200, David Hildenbrand wrote:
>> On 05.06.19 10:58, David Hildenbrand wrote:
>>>>> /*
>>>>> * 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).
>>
>> Correction: We already use it to block offlining of partially populated
>> memory blocks \o/
>
> Would you mind letting me know where we leverage this?
Sure:
drivers/base/memory.c:memory_subsys_offline()
if (mem->section_count != sections_per_block)
return -EINVAL;
I would have expected such checks in the offline_pages() function instead.
--
Thanks,
David / dhildenb
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-06-05 21:51 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190527111152.16324-1-david@redhat.com>
2019-05-27 11:11 ` [PATCH v3 01/11] mm/memory_hotplug: Simplify and fix check_hotplug_memory_range() David Hildenbrand
2019-05-30 17:53 ` Pavel Tatashin
2019-06-10 16:46 ` Oscar Salvador
2019-07-01 7:42 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 02/11] s390x/mm: Fail when an altmap is used for arch_add_memory() David Hildenbrand
2019-06-10 17:07 ` Oscar Salvador
2019-07-01 7:43 ` Michal Hocko
2019-07-01 12:46 ` Michal Hocko
2019-07-15 10:51 ` David Hildenbrand
2019-07-19 6:45 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 03/11] s390x/mm: Implement arch_remove_memory() David Hildenbrand
2019-07-01 7:45 ` Michal Hocko
2019-07-01 12:47 ` Michal Hocko
2019-07-15 10:45 ` David Hildenbrand
2019-05-27 11:11 ` [PATCH v3 04/11] arm64/mm: Add temporary arch_remove_memory() implementation David Hildenbrand
2019-06-03 21:41 ` Wei Yang
2019-06-04 6:56 ` David Hildenbrand
2019-06-04 17:36 ` Robin Murphy
2019-06-04 17:51 ` David Hildenbrand
2019-07-01 12:48 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 05/11] drivers/base/memory: Pass a block_id to init_memory_block() David Hildenbrand
2019-06-03 21:49 ` Wei Yang
2019-06-04 6:56 ` David Hildenbrand
2019-07-01 7:56 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory() David Hildenbrand
2019-05-30 21:07 ` Pavel Tatashin
2019-06-04 21:42 ` Wei Yang
2019-06-05 8:58 ` David Hildenbrand
2019-06-05 10:58 ` David Hildenbrand
2019-06-05 21:22 ` Wei Yang
2019-06-05 21:50 ` David Hildenbrand [this message]
2019-07-01 8:14 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 08/11] mm/memory_hotplug: Drop MHP_MEMBLOCK_API David Hildenbrand
2019-06-04 21:47 ` Wei Yang
2019-07-01 8:15 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 09/11] mm/memory_hotplug: Remove memory block devices before arch_remove_memory() David Hildenbrand
2019-06-04 22:07 ` Wei Yang
2019-06-05 9:00 ` David Hildenbrand
2019-07-01 8:41 ` Michal Hocko
2019-07-15 10:58 ` David Hildenbrand
2019-05-27 11:11 ` [PATCH v3 10/11] mm/memory_hotplug: Make unregister_memory_block_under_nodes() never fail David Hildenbrand
2019-06-05 21:21 ` Wei Yang
2019-06-10 16:56 ` Oscar Salvador
2019-07-01 8:51 ` Michal Hocko
2019-07-01 9:36 ` Oscar Salvador
2019-07-01 10:27 ` Michal Hocko
2019-07-15 11:10 ` David Hildenbrand
2019-07-16 8:46 ` Oscar Salvador
2019-07-16 11:08 ` David Hildenbrand
2019-07-16 11:09 ` David Hildenbrand
2019-07-19 6:05 ` Michal Hocko
2019-05-27 11:11 ` [PATCH v3 11/11] mm/memory_hotplug: Remove "zone" parameter from sparse_remove_one_section David Hildenbrand
2019-06-05 21:21 ` Wei Yang
2019-06-10 16:58 ` Oscar Salvador
2019-07-01 8:52 ` Michal Hocko
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