Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752197AbdFJO6o (ORCPT ); Sat, 10 Jun 2017 10:58:44 -0400 Received: from mail-ot0-f194.google.com ([74.125.82.194]:33733 "EHLO mail-ot0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751958AbdFJO6m (ORCPT ); Sat, 10 Jun 2017 10:58:42 -0400 MIME-Version: 1.0 In-Reply-To: References: <20170515085827.16474-1-mhocko@kernel.org> <20170515085827.16474-5-mhocko@kernel.org> From: Wei Yang Date: Sat, 10 Jun 2017 22:58:21 +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: 10770 Lines: 265 On Sat, Jun 10, 2017 at 5:56 PM, Wei Yang wrote: > 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. > Ok, I made a mistake here. The memory_block device is visible in this case, while the sysfs link between memory_block and node is not visible for the whole memory_block device. BTW, current register_mem_sect_under_node() will create the sysfs link between memory_block and node for each pfn, while actually we only need one link between them. If I am correct. If you think it is fine, I would like to change this one to create the link on section base. > 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 >>