Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751977AbdFJJ4Z (ORCPT ); Sat, 10 Jun 2017 05:56:25 -0400 Received: from mail-ot0-f193.google.com ([74.125.82.193]:32903 "EHLO mail-ot0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751890AbdFJJ4X (ORCPT ); Sat, 10 Jun 2017 05:56:23 -0400 MIME-Version: 1.0 In-Reply-To: <20170515085827.16474-5-mhocko@kernel.org> References: <20170515085827.16474-1-mhocko@kernel.org> <20170515085827.16474-5-mhocko@kernel.org> From: Wei Yang Date: Sat, 10 Jun 2017 17:56:02 +0800 Message-ID: Subject: Re: [PATCH 04/14] mm, memory_hotplug: get rid of is_zone_device_section To: Michal Hocko Cc: Andrew Morton , Linux-MM , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Jerome Glisse , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , David Rientjes , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko , Dan Williams Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9976 Lines: 252 On Mon, May 15, 2017 at 4:58 PM, Michal Hocko wrote: > From: Michal Hocko > > device memory hotplug hooks into regular memory hotplug only half way. > It needs memory sections to track struct pages but there is no > need/desire to associate those sections with memory blocks and export > them to the userspace via sysfs because they cannot be onlined anyway. > > This is currently expressed by for_device argument to arch_add_memory > which then makes sure to associate the given memory range with > ZONE_DEVICE. register_new_memory then relies on is_zone_device_section > to distinguish special memory hotplug from the regular one. While this > works now, later patches in this series want to move __add_zone outside > of arch_add_memory path so we have to come up with something else. > > Add want_memblock down the __add_pages path and use it to control > whether the section->memblock association should be done. arch_add_memory > then just trivially want memblock for everything but for_device hotplug. > > remove_memory_section doesn't need is_zone_device_section either. We can > simply skip all the memblock specific cleanup if there is no memblock > for the given section. > > This shouldn't introduce any functional change. > Hmm... one question about the memory_block behavior. In case one memory_block contains more than one memory section. If one section is "device zone", the whole memory_block is not visible in sysfs. Or until the whole memory_block is full, the sysfs is visible. This is the known behavior right? And in this case, the memory_block could be found. Would this introduce some problem when remove_memory_section()? > Changes since v1 > - return 0 if want_memblock == 0 from __add_section as per Jerome Glisse > > Changes since v2 > - fix remove_memory_section unlock on find_memory_block failure > as per Jerome - spotted by Evgeny Baskakov > > Tested-by: Dan Williams > Acked-by: Vlastimil Babka > Signed-off-by: Michal Hocko > --- > arch/ia64/mm/init.c | 2 +- > arch/powerpc/mm/mem.c | 2 +- > arch/s390/mm/init.c | 2 +- > arch/sh/mm/init.c | 2 +- > arch/x86/mm/init_32.c | 2 +- > arch/x86/mm/init_64.c | 2 +- > drivers/base/memory.c | 23 +++++++++-------------- > include/linux/memory_hotplug.h | 2 +- > mm/memory_hotplug.c | 9 ++++++--- > 9 files changed, 22 insertions(+), 24 deletions(-) > > diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c > index 8f3efa682ee8..39e2aeb4669d 100644 > --- a/arch/ia64/mm/init.c > +++ b/arch/ia64/mm/init.c > @@ -658,7 +658,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > > zone = pgdat->node_zones + > zone_for_memory(nid, start, size, ZONE_NORMAL, for_device); > - ret = __add_pages(nid, zone, start_pfn, nr_pages); > + ret = __add_pages(nid, zone, start_pfn, nr_pages, !for_device); > > if (ret) > printk("%s: Problem encountered in __add_pages() as ret=%d\n", > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index 9ee536ec0739..e6b2e6618b6c 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -151,7 +151,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > zone = pgdata->node_zones + > zone_for_memory(nid, start, size, 0, for_device); > > - return __add_pages(nid, zone, start_pfn, nr_pages); > + return __add_pages(nid, zone, start_pfn, nr_pages, !for_device); > } > > #ifdef CONFIG_MEMORY_HOTREMOVE > diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c > index ee6a1d3d4983..893cf88cf02d 100644 > --- a/arch/s390/mm/init.c > +++ b/arch/s390/mm/init.c > @@ -191,7 +191,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > continue; > nr_pages = (start_pfn + size_pages > zone_end_pfn) ? > zone_end_pfn - start_pfn : size_pages; > - rc = __add_pages(nid, zone, start_pfn, nr_pages); > + rc = __add_pages(nid, zone, start_pfn, nr_pages, !for_device); > if (rc) > break; > start_pfn += nr_pages; > diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c > index 75491862d900..a9d57f75ae8c 100644 > --- a/arch/sh/mm/init.c > +++ b/arch/sh/mm/init.c > @@ -498,7 +498,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > ret = __add_pages(nid, pgdat->node_zones + > zone_for_memory(nid, start, size, ZONE_NORMAL, > for_device), > - start_pfn, nr_pages); > + start_pfn, nr_pages, !for_device); > if (unlikely(ret)) > printk("%s: Failed, __add_pages() == %d\n", __func__, ret); > > diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c > index 99fb83819a5f..94594b889144 100644 > --- a/arch/x86/mm/init_32.c > +++ b/arch/x86/mm/init_32.c > @@ -831,7 +831,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > unsigned long start_pfn = start >> PAGE_SHIFT; > unsigned long nr_pages = size >> PAGE_SHIFT; > > - return __add_pages(nid, zone, start_pfn, nr_pages); > + return __add_pages(nid, zone, start_pfn, nr_pages, !for_device); > } > > #ifdef CONFIG_MEMORY_HOTREMOVE > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 41270b96403d..2e004364a373 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -697,7 +697,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device) > > init_memory_mapping(start, start + size); > > - ret = __add_pages(nid, zone, start_pfn, nr_pages); > + ret = __add_pages(nid, zone, start_pfn, nr_pages, !for_device); > WARN_ON_ONCE(ret); > > /* update max_pfn, max_low_pfn and high_memory */ > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 90225ffee501..f8fd562c3f18 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -685,14 +685,6 @@ static int add_memory_block(int base_section_nr) > return 0; > } > > -static bool is_zone_device_section(struct mem_section *ms) > -{ > - struct page *page; > - > - page = sparse_decode_mem_map(ms->section_mem_map, __section_nr(ms)); > - return is_zone_device_page(page); > -} > - > /* > * need an interface for the VM to add new memory regions, > * but without onlining it. > @@ -702,9 +694,6 @@ int register_new_memory(int nid, struct mem_section *section) > int ret = 0; > struct memory_block *mem; > > - if (is_zone_device_section(section)) > - return 0; > - > mutex_lock(&mem_sysfs_mutex); > > mem = find_memory_block(section); > @@ -741,11 +730,16 @@ static int remove_memory_section(unsigned long node_id, > { > struct memory_block *mem; > > - if (is_zone_device_section(section)) > - return 0; > - > mutex_lock(&mem_sysfs_mutex); > + > + /* > + * Some users of the memory hotplug do not want/need memblock to > + * track all sections. Skip over those. > + */ > mem = find_memory_block(section); > + if (!mem) > + goto out_unlock; > + > unregister_mem_sect_under_nodes(mem, __section_nr(section)); > > mem->section_count--; > @@ -754,6 +748,7 @@ static int remove_memory_section(unsigned long node_id, > else > put_device(&mem->dev); > > +out_unlock: > mutex_unlock(&mem_sysfs_mutex); > return 0; > } > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 134a2f69c21a..3c8cf86201c3 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -111,7 +111,7 @@ extern int __remove_pages(struct zone *zone, unsigned long start_pfn, > > /* reasonably generic interface to expand the physical pages in a zone */ > extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn, > - unsigned long nr_pages); > + unsigned long nr_pages, bool want_memblock); > > #ifdef CONFIG_NUMA > extern int memory_add_physaddr_to_nid(u64 start); > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 6290d34b6331..a95120c56a9a 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -494,7 +494,7 @@ static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn) > } > > static int __meminit __add_section(int nid, struct zone *zone, > - unsigned long phys_start_pfn) > + unsigned long phys_start_pfn, bool want_memblock) > { > int ret; > > @@ -511,6 +511,9 @@ static int __meminit __add_section(int nid, struct zone *zone, > if (ret < 0) > return ret; > > + if (!want_memblock) > + return 0; > + > return register_new_memory(nid, __pfn_to_section(phys_start_pfn)); > } > > @@ -521,7 +524,7 @@ static int __meminit __add_section(int nid, struct zone *zone, > * add the new pages. > */ > int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn, > - unsigned long nr_pages) > + unsigned long nr_pages, bool want_memblock) > { > unsigned long i; > int err = 0; > @@ -549,7 +552,7 @@ int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn, > } > > for (i = start_sec; i <= end_sec; i++) { > - err = __add_section(nid, zone, section_nr_to_pfn(i)); > + err = __add_section(nid, zone, section_nr_to_pfn(i), want_memblock); > > /* > * EEXIST is finally dealt with by ioresource collision > -- > 2.11.0 >