diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig.debug | 9 | ||||
| -rw-r--r-- | mm/Makefile | 1 | ||||
| -rw-r--r-- | mm/page_alloc.c | 2 | ||||
| -rw-r--r-- | mm/page_ext.c | 395 |
4 files changed, 407 insertions, 0 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 4b24432..1ba81c7 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -1,3 +1,12 @@ +config PAGE_EXTENSION + bool "Extend memmap on extra space for more information on page" + ---help--- + Extend memmap on extra space for more information on page. This + could be used for debugging features that need to insert extra + field for every page. This extension enables us to save memory + by not allocating this extra memory according to boottime + configuration. + config DEBUG_PAGEALLOC bool "Debug page memory allocations" depends on DEBUG_KERNEL diff --git a/mm/Makefile b/mm/Makefile index b3c6ce9..580cd3f 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -71,3 +71,4 @@ obj-$(CONFIG_ZSMALLOC) += zsmalloc.o obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o obj-$(CONFIG_CMA) += cma.o obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o +obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2e8b7f3..b64666c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -48,6 +48,7 @@ #include <linux/backing-dev.h> #include <linux/fault-inject.h> #include <linux/page-isolation.h> +#include <linux/page_ext.h> #include <linux/debugobjects.h> #include <linux/kmemleak.h> #include <linux/compaction.h> @@ -4856,6 +4857,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat, #endif init_waitqueue_head(&pgdat->kswapd_wait); init_waitqueue_head(&pgdat->pfmemalloc_wait); + pgdat_page_ext_init(pgdat); for (j = 0; j < MAX_NR_ZONES; j++) { struct zone *zone = pgdat->node_zones + j; diff --git a/mm/page_ext.c b/mm/page_ext.c new file mode 100644 index 0000000..514a3bc --- /dev/null +++ b/mm/page_ext.c @@ -0,0 +1,395 @@ +#include <linux/mm.h> +#include <linux/mmzone.h> +#include <linux/bootmem.h> +#include <linux/page_ext.h> +#include <linux/memory.h> +#include <linux/vmalloc.h> +#include <linux/kmemleak.h> + +/* + * struct page extension + * + * This is the feature to manage memory for extended data per page. + * + * Until now, we must modify struct page itself to store extra data per page. + * This requires rebuilding the kernel and it is really time consuming process. + * And, sometimes, rebuild is impossible due to third party module dependency. + * At last, enlarging struct page could cause un-wanted system behaviour change. + * + * This feature is intended to overcome above mentioned problems. This feature + * allocates memory for extended data per page in certain place rather than + * the struct page itself. This memory can be accessed by the accessor + * functions provided by this code. During the boot process, it checks whether + * allocation of huge chunk of memory is needed or not. If not, it avoids + * allocating memory at all. With this advantage, we can include this feature + * into the kernel in default and can avoid rebuild and solve related problems. + * + * To help these things to work well, there are two callbacks for clients. One + * is the need callback which is mandatory if user wants to avoid useless + * memory allocation at boot-time. The other is optional, init callback, which + * is used to do proper initialization after memory is allocated. + * + * The need callback is used to decide whether extended memory allocation is + * needed or not. Sometimes users want to deactivate some features in this + * boot and extra memory would be unneccessary. In this case, to avoid + * allocating huge chunk of memory, each clients represent their need of + * extra memory through the need callback. If one of the need callbacks + * returns true, it means that someone needs extra memory so that + * page extension core should allocates memory for page extension. If + * none of need callbacks return true, memory isn't needed at all in this boot + * and page extension core can skip to allocate memory. As result, + * none of memory is wasted. + * + * The init callback is used to do proper initialization after page extension + * is completely initialized. In sparse memory system, extra memory is + * allocated some time later than memmap is allocated. In other words, lifetime + * of memory for page extension isn't same with memmap for struct page. + * Therefore, clients can't store extra data until page extension is + * initialized, even if pages are allocated and used freely. This could + * cause inadequate state of extra data per page, so, to prevent it, client + * can utilize this callback to initialize the state of it correctly. + */ + +static struct page_ext_operations *page_ext_ops[] = { +}; + +static unsigned long total_usage; + +static bool __init invoke_need_callbacks(void) +{ + int i; + int entries = ARRAY_SIZE(page_ext_ops); + + for (i = 0; i < entries; i++) { + if (page_ext_ops[i]->need && page_ext_ops[i]->need()) + return true; + } + + return false; +} + +static void __init invoke_init_callbacks(void) +{ + int i; + int entries = ARRAY_SIZE(page_ext_ops); + + for (i = 0; i < entries; i++) { + if (page_ext_ops[i]->init) + page_ext_ops[i]->init(); + } +} + +#if !defined(CONFIG_SPARSEMEM) + + +void __meminit pgdat_page_ext_init(struct pglist_data *pgdat) +{ + pgdat->node_page_ext = NULL; +} + +struct page_ext *lookup_page_ext(struct page *page) +{ + unsigned long pfn = page_to_pfn(page); + unsigned long offset; + struct page_ext *base; + + base = NODE_DATA(page_to_nid(page))->node_page_ext; +#ifdef CONFIG_DEBUG_VM + /* + * The sanity checks the page allocator does upon freeing a + * page can reach here before the page_ext arrays are + * allocated when feeding a range of pages to the allocator + * for the first time during bootup or memory hotplug. + */ + if (unlikely(!base)) + return NULL; +#endif + offset = pfn - round_down(node_start_pfn(page_to_nid(page)), + MAX_ORDER_NR_PAGES); + return base + offset; +} + +static int __init alloc_node_page_ext(int nid) +{ + struct page_ext *base; + unsigned long table_size; + unsigned long nr_pages; + + nr_pages = NODE_DATA(nid)->node_spanned_pages; + if (!nr_pages) + return 0; + + /* + * Need extra space if node range is not aligned with + * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm + * checks buddy's status, range could be out of exact node range. + */ + if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) || + !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES)) + nr_pages += MAX_ORDER_NR_PAGES; + + table_size = sizeof(struct page_ext) * nr_pages; + + base = memblock_virt_alloc_try_nid_nopanic( + table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS), + BOOTMEM_ALLOC_ACCESSIBLE, nid); + if (!base) + return -ENOMEM; + NODE_DATA(nid)->node_page_ext = base; + total_usage += table_size; + return 0; +} + +void __init page_ext_init_flatmem(void) +{ + + int nid, fail; + + if (!invoke_need_callbacks()) + return; + + for_each_online_node(nid) { + fail = alloc_node_page_ext(nid); + if (fail) + goto fail; + } + pr_info("allocated %ld bytes of page_ext\n", total_usage); + invoke_init_callbacks(); + return; + +fail: + pr_crit("allocation of page_ext failed.\n"); + panic("Out of memory"); +} + +#else /* CONFIG_FLAT_NODE_MEM_MAP */ + +struct page_ext *lookup_page_ext(struct page *page) +{ + unsigned long pfn = page_to_pfn(page); + struct mem_section *section = __pfn_to_section(pfn); +#ifdef CONFIG_DEBUG_VM + /* + * The sanity checks the page allocator does upon freeing a + * page can reach here before the page_ext arrays are + * allocated when feeding a range of pages to the allocator + * for the first time during bootup or memory hotplug. + */ + if (!section->page_ext) + return NULL; +#endif + return section->page_ext + pfn; +} + +static void *__meminit alloc_page_ext(size_t size, int nid) +{ + gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN; + void *addr = NULL; + + addr = alloc_pages_exact_nid(nid, size, flags); + if (addr) { + kmemleak_alloc(addr, size, 1, flags); + return addr; + } + + if (node_state(nid, N_HIGH_MEMORY)) + addr = vzalloc_node(size, nid); + else + addr = vzalloc(size); + + return addr; +} + +static int __meminit init_section_page_ext(unsigned long pfn, int nid) +{ + struct mem_section *section; + struct page_ext *base; + unsigned long table_size; + + section = __pfn_to_section(pfn); + + if (section->page_ext) + return 0; + + table_size = sizeof(struct page_ext) * PAGES_PER_SECTION; + base = alloc_page_ext(table_size, nid); + + /* + * The value stored in section->page_ext is (base - pfn) + * and it does not point to the memory block allocated above, + * causing kmemleak false positives. + */ + kmemleak_not_leak(base); + + if (!base) { + pr_err("page ext allocation failure\n"); + return -ENOMEM; + } + + /* + * The passed "pfn" may not be aligned to SECTION. For the calculation + * we need to apply a mask. + */ + pfn &= PAGE_SECTION_MASK; + section->page_ext = base - pfn; + total_usage += table_size; + return 0; +} +#ifdef CONFIG_MEMORY_HOTPLUG +static void free_page_ext(void *addr) +{ + if (is_vmalloc_addr(addr)) { + vfree(addr); + } else { + struct page *page = virt_to_page(addr); + size_t table_size; + + table_size = sizeof(struct page_ext) * PAGES_PER_SECTION; + + BUG_ON(PageReserved(page)); + free_pages_exact(addr, table_size); + } +} + +static void __free_page_ext(unsigned long pfn) +{ + struct mem_section *ms; + struct page_ext *base; + + ms = __pfn_to_section(pfn); + if (!ms || !ms->page_ext) + return; + base = ms->page_ext + pfn; + free_page_ext(base); + ms->page_ext = NULL; +} + +static int __meminit online_page_ext(unsigned long start_pfn, + unsigned long nr_pages, + int nid) +{ + unsigned long start, end, pfn; + int fail = 0; + + start = SECTION_ALIGN_DOWN(start_pfn); + end = SECTION_ALIGN_UP(start_pfn + nr_pages); + + if (nid == -1) { + /* + * In this case, "nid" already exists and contains valid memory. + * "start_pfn" passed to us is a pfn which is an arg for + * online__pages(), and start_pfn should exist. + */ + nid = pfn_to_nid(start_pfn); + VM_BUG_ON(!node_state(nid, N_ONLINE)); + } + + for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) { + if (!pfn_present(pfn)) + continue; + fail = init_section_page_ext(pfn, nid); + } + if (!fail) + return 0; + + /* rollback */ + for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) + __free_page_ext(pfn); + + return -ENOMEM; +} + +static int __meminit offline_page_ext(unsigned long start_pfn, + unsigned long nr_pages, int nid) +{ + unsigned long start, end, pfn; + + start = SECTION_ALIGN_DOWN(start_pfn); + end = SECTION_ALIGN_UP(start_pfn + nr_pages); + + for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) + __free_page_ext(pfn); + return 0; + +} + +static int __meminit page_ext_callback(struct notifier_block *self, + unsigned long action, void *arg) +{ + struct memory_notify *mn = arg; + int ret = 0; + + switch (action) { + case MEM_GOING_ONLINE: + ret = online_page_ext(mn->start_pfn, + mn->nr_pages, mn->status_change_nid); + break; + case MEM_OFFLINE: + offline_page_ext(mn->start_pfn, + mn->nr_pages, mn->status_change_nid); + break; + case MEM_CANCEL_ONLINE: + offline_page_ext(mn->start_pfn, + mn->nr_pages, mn->status_change_nid); + break; + case MEM_GOING_OFFLINE: + break; + case MEM_ONLINE: + case MEM_CANCEL_OFFLINE: + break; + } + + return notifier_from_errno(ret); +} + +#endif + +void __init page_ext_init(void) +{ + unsigned long pfn; + int nid; + + if (!invoke_need_callbacks()) + return; + + for_each_node_state(nid, N_MEMORY) { + unsigned long start_pfn, end_pfn; + + start_pfn = node_start_pfn(nid); + end_pfn = node_end_pfn(nid); + /* + * start_pfn and end_pfn may not be aligned to SECTION and the + * page->flags of out of node pages are not initialized. So we + * scan [start_pfn, the biggest section's pfn < end_pfn) here. + */ + for (pfn = start_pfn; pfn < end_pfn; + pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) { + + if (!pfn_valid(pfn)) + continue; + /* + * Nodes's pfns can be overlapping. + * We know some arch can have a nodes layout such as + * -------------pfn--------------> + * N0 | N1 | N2 | N0 | N1 | N2|.... + */ + if (pfn_to_nid(pfn) != nid) + continue; + if (init_section_page_ext(pfn, nid)) + goto oom; + } + } + hotplug_memory_notifier(page_ext_callback, 0); + pr_info("allocated %ld bytes of page_ext\n", total_usage); + invoke_init_callbacks(); + return; + +oom: + panic("Out of memory"); +} + +void __meminit pgdat_page_ext_init(struct pglist_data *pgdat) +{ +} + +#endif |
