From: David Hildenbrand <david@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-ia64@vger.kernel.org,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
Linux-sh <linux-sh@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"mike.travis@hpe.com" <mike.travis@hpe.com>,
Ingo Molnar <mingo@kernel.org>,
Andrew Banman <andrew.banman@hpe.com>,
Oscar Salvador <osalvador@suse.de>,
Michal Hocko <mhocko@suse.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>, Qian Cai <cai@lca.pw>,
Wei Yang <richard.weiyang@gmail.com>,
Arun KS <arunks@codeaurora.org>,
Mathieu Malaterre <malat@debian.org>
Subject: Re: [PATCH v2 4/8] mm/memory_hotplug: Create memory block devices after arch_add_memory()
Date: Tue, 7 May 2019 23:27:17 +0200 [thread overview]
Message-ID: <a41438f2-6bac-a2ad-96ec-234762c1cd37@redhat.com> (raw)
In-Reply-To: <CAPcyv4jiVyaPbUrQwSiy65xk=EegJwuGSDKkVYWkGiTJz847gg@mail.gmail.com>
>> +static void unregister_memory(struct memory_block *memory)
>> +{
>> + BUG_ON(memory->dev.bus != &memory_subsys);
>
> Given this should never happen and only a future kernel developer
> might trip over it, do we really need to kill that developer's
> machine? I.e. s/BUG/WARN/? I guess an argument can be made to move
> such a change that to a follow-on patch since you're just preserving
> existing behavior, but I figure might as well address these as the
> code is refactored.
I assume only
if (WARN ...)
return;
makes sense then, right?
>
>> +
>> + /* 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 hotplug_memory_register(unsigned long start, unsigned long size)
>> {
>> - int ret = 0;
>> + unsigned long block_nr_pages = memory_block_size_bytes() >> PAGE_SHIFT;
>> + unsigned long start_pfn = PFN_DOWN(start);
>> + unsigned long end_pfn = start_pfn + (size >> PAGE_SHIFT);
>> + unsigned long pfn;
>> struct memory_block *mem;
>> + int ret = 0;
>>
>> - mutex_lock(&mem_sysfs_mutex);
>> + BUG_ON(!IS_ALIGNED(start, memory_block_size_bytes()));
>> + BUG_ON(!IS_ALIGNED(size, memory_block_size_bytes()));
>
> Perhaps:
>
> if (WARN_ON(...))
> return -EINVAL;
>
Yes, guess this souldn't hurt.
>>
>> - mem = find_memory_block(section);
>> - if (mem) {
>> - mem->section_count++;
>> - put_device(&mem->dev);
>> - } else {
>> - ret = init_memory_block(&mem, section, MEM_OFFLINE);
>> + mutex_lock(&mem_sysfs_mutex);
>> + for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) {
>> + mem = find_memory_block(__pfn_to_section(pfn));
>> + if (mem) {
>> + WARN_ON_ONCE(false);
>
> ?? Isn't that a nop?
Yes, that makes no sense :)
Thanks!
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-05-07 21:27 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190507183804.5512-1-david@redhat.com>
2019-05-07 18:37 ` [PATCH v2 1/8] mm/memory_hotplug: Simplify and fix check_hotplug_memory_range() David Hildenbrand
2019-05-07 20:38 ` Dan Williams
2019-05-09 12:23 ` Wei Yang
2019-05-07 18:37 ` [PATCH v2 2/8] s390x/mm: Implement arch_remove_memory() David Hildenbrand
2019-05-07 20:46 ` Dan Williams
2019-05-07 20:47 ` David Hildenbrand
2019-05-07 20:57 ` Dan Williams
2019-05-07 21:13 ` David Hildenbrand
2019-05-07 18:38 ` [PATCH v2 4/8] mm/memory_hotplug: Create memory block devices after arch_add_memory() David Hildenbrand
2019-05-07 21:17 ` Dan Williams
2019-05-07 21:27 ` David Hildenbrand [this message]
2019-05-08 8:35 ` David Hildenbrand
2019-05-09 12:43 ` Wei Yang
2019-05-09 12:50 ` David Hildenbrand
2019-05-09 13:55 ` Wei Yang
2019-05-09 14:05 ` David Hildenbrand
2019-05-09 14:31 ` Wei Yang
2019-05-09 14:58 ` David Hildenbrand
2019-05-09 21:50 ` Wei Yang
2019-05-09 22:18 ` David Hildenbrand
2019-05-07 18:38 ` [PATCH v2 5/8] mm/memory_hotplug: Drop MHP_MEMBLOCK_API David Hildenbrand
2019-05-07 21:19 ` Dan Williams
2019-05-07 21:24 ` David Hildenbrand
2019-05-07 21:25 ` Dan Williams
2019-05-08 7:39 ` David Hildenbrand
2019-05-08 23:08 ` osalvador
2019-05-09 7:05 ` David Hildenbrand
2019-05-07 18:38 ` [PATCH v2 6/8] mm/memory_hotplug: Remove memory block devices before arch_remove_memory() David Hildenbrand
2019-05-07 21:27 ` Dan Williams
2019-05-07 18:38 ` [PATCH v2 7/8] mm/memory_hotplug: Make unregister_memory_block_under_nodes() never fail David Hildenbrand
2019-05-08 0:15 ` Dan Williams
2019-05-08 7:21 ` David Hildenbrand
2019-05-08 13:50 ` Dan Williams
2019-05-07 18:38 ` [PATCH v2 8/8] mm/memory_hotplug: Remove "zone" parameter from sparse_remove_one_section David Hildenbrand
2019-05-08 0:30 ` Dan Williams
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