From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Date: Wed, 01 Aug 2012 06:09:27 +0000 Subject: Re: [RFC PATCH v5 16/19] memory-hotplug: free memmap of sparse-vmemmap Message-Id: <5018C817.80509@cn.fujitsu.com> List-Id: References: <50126B83.3050201@cn.fujitsu.com> <50126EBE.1020006@cn.fujitsu.com> <20120731142251.5b2cae37@thinkpad> In-Reply-To: <20120731142251.5b2cae37@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: gerald.schaefer@de.ibm.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com, Yasuaki ISIMATU At 07/31/2012 08:22 PM, Gerald Schaefer Wrote: > On Fri, 27 Jul 2012 18:34:38 +0800 > Wen Congyang wrote: > >> From: Yasuaki Ishimatsu >> >> All pages of virtual mapping in removed memory cannot be freed, since >> some pages used as PGD/PUD includes not only removed memory but also >> other memory. So the patch checks whether page can be freed or not. >> >> How to check whether page can be freed or not? >> 1. When removing memory, the page structs of the revmoved memory are >> filled with 0FD. >> 2. All page structs are filled with 0xFD on PT/PMD, PT/PMD can be >> cleared. In this case, the page used as PT/PMD can be freed. >> >> Applying patch, __remove_section() of CONFIG_SPARSEMEM_VMEMMAP is >> integrated into one. So __remove_section() of >> CONFIG_SPARSEMEM_VMEMMAP is deleted. > > There should also be generic or dummy versions of the functions > vmemmap_free_bootmem(), vmemmap_kfree() and > register_page_bootmem_memmap(). It doesn't compile on other > archtitectures than x86 as it is now: > > mm/built-in.o: In function `sparse_remove_one_section': > (.text+0x49fa6): undefined reference to `vmemmap_free_bootmem' > mm/built-in.o: In function `sparse_remove_one_section': > (.text+0x49fcc): undefined reference to `vmemmap_kfree' > mm/built-in.o: In function `register_page_bootmem_info_node': > (.text+0x57c06): undefined reference to `register_page_bootmem_memmap' > mm/built-in.o: In function `sparse_add_one_section': > (.meminit.text+0x2506): undefined reference to `vmemmap_kfree' > mm/built-in.o: In function `sparse_add_one_section': > (.meminit.text+0x2528): undefined reference to `vmemmap_kfree' > make: *** [vmlinux] Error 1 > > Thanks for testing. I will fix it. Wen Congyang