Re: [PATCH v2 2/2] Register bootmem pages
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2013-08-27 03:45:01
On Mon, 2013-08-19 at 21:53 -0500, Nathan Fontenot wrote:
Previous commit 46723bfa540... introduced a new config option HAVE_BOOTMEM_INFO_NODE that ended up breaking memory hot-remove for ppc when sparse vmemmap is not defined. This patch defines HAVE_BOOTMEM_INFO_NODE for ppc and adds the call to register_page_bootmem_info_node. Without this we get a BUG_ON for memory hot remove in put_page_bootmem(). This also adds a stub for register_page_bootmem_memmap to allow ppc to build with sparse vmemmap defined. Signed-off-by: Nathan Fontenot <redacted> ---
So I still feel very uncomfortable with that stuff .... For example, x86 calls register_page_bootmem_info_node() at boot time, which does that strange "get_page_bootmem" on the NODE_DATA itself at boot time, we don't. Should we ? Since we don't, what do that mean ? We don't remove the node info pages on unplug ? Is that ok ? There's a whole pile of totally undocumented / uncommented generic code with horrible function names in there whose sematic is very very unclear. Now, if we call that thing, are we expected to have register_paqe_bootmem_memmap() to actually do something right? I assume that means actually calling get_page_bootmem() on the various struct page that comprise the vmemmap. Well, we can probably implement that since we maintain a list of all the vmemap pages... However, we don't implement vmemmap_free(). Should we ? This all confuses me... Cheers, Ben.
quoted hunk ↗ jump to hunk
--- arch/powerpc/mm/init_64.c | 4 ++++ arch/powerpc/mm/mem.c | 9 +++++++++ mm/Kconfig | 2 +- 3 files changed, 14 insertions(+), 1 deletion(-) Index: linux/arch/powerpc/mm/init_64.c ===================================================================--- linux.orig/arch/powerpc/mm/init_64.c +++ linux/arch/powerpc/mm/init_64.c@@ -300,5 +300,9 @@ void vmemmap_free(unsigned long start, u { } +void register_page_bootmem_memmap(unsigned long section_nr, + struct page *start_page, unsigned long size) +{ +} #endif /* CONFIG_SPARSEMEM_VMEMMAP */Index: linux/arch/powerpc/mm/mem.c ===================================================================--- linux.orig/arch/powerpc/mm/mem.c +++ linux/arch/powerpc/mm/mem.c@@ -297,12 +297,21 @@ void __init paging_init(void) } #endif /* ! CONFIG_NEED_MULTIPLE_NODES */ +static void __init register_page_bootmem_info(void) +{ + int i; + + for_each_online_node(i) + register_page_bootmem_info_node(NODE_DATA(i)); +} + void __init mem_init(void) { #ifdef CONFIG_SWIOTLB swiotlb_init(0); #endif + register_page_bootmem_info(); high_memory = (void *) __va(max_low_pfn * PAGE_SIZE); set_max_mapnr(max_pfn); free_all_bootmem();Index: linux/mm/Kconfig ===================================================================--- linux.orig/mm/Kconfig +++ linux/mm/Kconfig@@ -183,7 +183,7 @@ config MEMORY_HOTPLUG_SPARSE config MEMORY_HOTREMOVE bool "Allow for memory hot remove" select MEMORY_ISOLATION - select HAVE_BOOTMEM_INFO_NODE if X86_64 + select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE depends on MIGRATION_______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev