On Fri, 27 Jul 2012 18:34:38 +0800 Wen Congyang <wency@xxxxxxxxxxxxxx> wrote: > From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > > 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>