From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Wed, 08 May 2019 08:35:26 +0000 Subject: Re: [PATCH v2 4/8] mm/memory_hotplug: Create memory block devices after arch_add_memory() Message-Id: <094f6f72-b02f-585f-6ffa-d631c71808d6@redhat.com> List-Id: References: <20190507183804.5512-1-david@redhat.com> <20190507183804.5512-5-david@redhat.com> In-Reply-To: <20190507183804.5512-5-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-mm@kvack.org Cc: 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, akpm@linux-foundation.org, Dan Williams , Greg Kroah-Hartman , "Rafael J. Wysocki" , "mike.travis@hpe.com" , Ingo Molnar , Andrew Banman , Oscar Salvador , Michal Hocko , Pavel Tatashin , Qian Cai , Wei Yang , Arun KS , Mathieu Malaterre On 07.05.19 20:38, David Hildenbrand wrote: > Only memory to be added to the buddy and to be onlined/offlined by > user space using memory block devices needs (and should have!) memory > block devices. > > Factor out creation of memory block devices Create all devices after > arch_add_memory() succeeded. We can later drop the want_memblock parameter, > because it is now effectively stale. > > Only after memory block devices have been added, memory can be onlined > by user space. This implies, that memory is not visible to user space at > all before arch_add_memory() succeeded. > > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Cc: David Hildenbrand > Cc: "mike.travis@hpe.com" > Cc: Andrew Morton > Cc: Ingo Molnar > Cc: Andrew Banman > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: Pavel Tatashin > Cc: Qian Cai > Cc: Wei Yang > Cc: Arun KS > Cc: Mathieu Malaterre > Signed-off-by: David Hildenbrand > --- > drivers/base/memory.c | 70 ++++++++++++++++++++++++++---------------- > include/linux/memory.h | 2 +- > mm/memory_hotplug.c | 15 ++++----- > 3 files changed, 53 insertions(+), 34 deletions(-) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 6e0cb4fda179..862c202a18ca 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -701,44 +701,62 @@ static int add_memory_block(int base_section_nr) > return 0; > } > > +static void unregister_memory(struct memory_block *memory) > +{ > + BUG_ON(memory->dev.bus != &memory_subsys); > + > + /* 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())); > > - 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); > + put_device(&mem->dev); > + continue; > + } > + ret = init_memory_block(&mem, __pfn_to_section(pfn), > + MEM_OFFLINE); > if (ret) > - goto out; > - mem->section_count++; > + break; > + mem->section_count = memory_block_size_bytes() / > + MIN_MEMORY_BLOCK_SIZE; > + } > + if (ret) { > + end_pfn = pfn; > + for (pfn = start_pfn; pfn != end_pfn; pfn += block_nr_pages) { > + mem = find_memory_block(__pfn_to_section(pfn)); > + if (!mem) > + continue; > + mem->section_count = 0; > + unregister_memory(mem); > + } > } > - > -out: > mutex_unlock(&mem_sysfs_mutex); > return ret; > } > > -static void > -unregister_memory(struct memory_block *memory) > -{ > - BUG_ON(memory->dev.bus != &memory_subsys); > - > - /* drop the ref. we got via find_memory_block() */ > - put_device(&memory->dev); > - device_unregister(&memory->dev); > -} > - > -void unregister_memory_section(struct mem_section *section) > +static int remove_memory_section(struct mem_section *section) > { The function change is misplaces in this patch will drop it so this patch compiles without the other patches. -- Thanks, David / dhildenb