diff options
Diffstat (limited to 'mm/page_ext.c')
| -rw-r--r-- | mm/page_ext.c | 174 |
1 files changed, 148 insertions, 26 deletions
diff --git a/mm/page_ext.c b/mm/page_ext.c index a3616f7a0e9e..4548fcc66d74 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -8,6 +8,8 @@ #include <linux/kmemleak.h> #include <linux/page_owner.h> #include <linux/page_idle.h> +#include <linux/page_table_check.h> +#include <linux/rcupdate.h> /* * struct page extension @@ -34,7 +36,7 @@ * * 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 + * boot and extra memory would be unnecessary. 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 @@ -58,19 +60,45 @@ * can utilize this callback to initialize the state of it correctly. */ -static struct page_ext_operations *page_ext_ops[] = { +#ifdef CONFIG_SPARSEMEM +#define PAGE_EXT_INVALID (0x1) +#endif + +#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT) +static bool need_page_idle(void) +{ + return true; +} +static struct page_ext_operations page_idle_ops __initdata = { + .need = need_page_idle, + .need_shared_flags = true, +}; +#endif + +static struct page_ext_operations *page_ext_ops[] __initdata = { #ifdef CONFIG_PAGE_OWNER &page_owner_ops, #endif -#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT) +#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT) &page_idle_ops, #endif +#ifdef CONFIG_PAGE_TABLE_CHECK + &page_table_check_ops, +#endif }; -unsigned long page_ext_size = sizeof(struct page_ext); +unsigned long page_ext_size; static unsigned long total_usage; +bool early_page_ext __meminitdata; +static int __init setup_early_page_ext(char *str) +{ + early_page_ext = true; + return 0; +} +early_param("early_page_ext", setup_early_page_ext); + static bool __init invoke_need_callbacks(void) { int i; @@ -78,7 +106,16 @@ static bool __init invoke_need_callbacks(void) bool need = false; for (i = 0; i < entries; i++) { - if (page_ext_ops[i]->need && page_ext_ops[i]->need()) { + if (page_ext_ops[i]->need()) { + if (page_ext_ops[i]->need_shared_flags) { + page_ext_size = sizeof(struct page_ext); + break; + } + } + } + + for (i = 0; i < entries; i++) { + if (page_ext_ops[i]->need()) { page_ext_ops[i]->offset = page_ext_size; page_ext_size += page_ext_ops[i]->size; need = true; @@ -104,20 +141,24 @@ static inline struct page_ext *get_entry(void *base, unsigned long index) return base + page_ext_size * index; } -#if !defined(CONFIG_SPARSEMEM) - +#ifndef CONFIG_SPARSEMEM +void __init page_ext_init_flatmem_late(void) +{ + invoke_init_callbacks(); +} void __meminit pgdat_page_ext_init(struct pglist_data *pgdat) { pgdat->node_page_ext = NULL; } -struct page_ext *lookup_page_ext(const struct page *page) +static struct page_ext *lookup_page_ext(const struct page *page) { unsigned long pfn = page_to_pfn(page); unsigned long index; struct page_ext *base; + WARN_ON_ONCE(!rcu_read_lock_held()); base = NODE_DATA(page_to_nid(page))->node_page_ext; /* * The sanity checks the page allocator does upon freeing a @@ -177,7 +218,6 @@ void __init page_ext_init_flatmem(void) goto fail; } pr_info("allocated %ld bytes of page_ext\n", total_usage); - invoke_init_callbacks(); return; fail: @@ -185,21 +225,28 @@ fail: panic("Out of memory"); } -#else /* CONFIG_FLAT_NODE_MEM_MAP */ +#else /* CONFIG_SPARSEMEM */ +static bool page_ext_invalid(struct page_ext *page_ext) +{ + return !page_ext || (((unsigned long)page_ext & PAGE_EXT_INVALID) == PAGE_EXT_INVALID); +} -struct page_ext *lookup_page_ext(const struct page *page) +static struct page_ext *lookup_page_ext(const struct page *page) { unsigned long pfn = page_to_pfn(page); struct mem_section *section = __pfn_to_section(pfn); + struct page_ext *page_ext = READ_ONCE(section->page_ext); + + WARN_ON_ONCE(!rcu_read_lock_held()); /* * 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) + if (page_ext_invalid(page_ext)) return NULL; - return get_entry(section->page_ext, pfn); + return get_entry(page_ext, pfn); } static void *__meminit alloc_page_ext(size_t size, int nid) @@ -253,7 +300,7 @@ static int __meminit init_section_page_ext(unsigned long pfn, int nid) total_usage += table_size; return 0; } -#ifdef CONFIG_MEMORY_HOTPLUG + static void free_page_ext(void *addr) { if (is_vmalloc_addr(addr)) { @@ -278,9 +325,30 @@ static void __free_page_ext(unsigned long pfn) ms = __pfn_to_section(pfn); if (!ms || !ms->page_ext) return; - base = get_entry(ms->page_ext, pfn); + + base = READ_ONCE(ms->page_ext); + /* + * page_ext here can be valid while doing the roll back + * operation in online_page_ext(). + */ + if (page_ext_invalid(base)) + base = (void *)base - PAGE_EXT_INVALID; + WRITE_ONCE(ms->page_ext, NULL); + + base = get_entry(base, pfn); free_page_ext(base); - ms->page_ext = NULL; +} + +static void __invalidate_page_ext(unsigned long pfn) +{ + struct mem_section *ms; + void *val; + + ms = __pfn_to_section(pfn); + if (!ms || !ms->page_ext) + return; + val = (void *)ms->page_ext + PAGE_EXT_INVALID; + WRITE_ONCE(ms->page_ext, val); } static int __meminit online_page_ext(unsigned long start_pfn, @@ -300,7 +368,7 @@ static int __meminit online_page_ext(unsigned long start_pfn, * online__pages(), and start_pfn should exist. */ nid = pfn_to_nid(start_pfn); - VM_BUG_ON(!node_state(nid, N_ONLINE)); + VM_BUG_ON(!node_online(nid)); } for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) @@ -309,24 +377,37 @@ static int __meminit online_page_ext(unsigned long start_pfn, return 0; /* rollback */ + end = pfn - PAGES_PER_SECTION; 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) +static void __meminit offline_page_ext(unsigned long start_pfn, + unsigned long nr_pages) { unsigned long start, end, pfn; start = SECTION_ALIGN_DOWN(start_pfn); end = SECTION_ALIGN_UP(start_pfn + nr_pages); + /* + * Freeing of page_ext is done in 3 steps to avoid + * use-after-free of it: + * 1) Traverse all the sections and mark their page_ext + * as invalid. + * 2) Wait for all the existing users of page_ext who + * started before invalidation to finish. + * 3) Free the page_ext. + */ for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) - __free_page_ext(pfn); - return 0; + __invalidate_page_ext(pfn); + + synchronize_rcu(); + for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) + __free_page_ext(pfn); } static int __meminit page_ext_callback(struct notifier_block *self, @@ -342,11 +423,11 @@ static int __meminit page_ext_callback(struct notifier_block *self, break; case MEM_OFFLINE: offline_page_ext(mn->start_pfn, - mn->nr_pages, mn->status_change_nid); + mn->nr_pages); break; case MEM_CANCEL_ONLINE: offline_page_ext(mn->start_pfn, - mn->nr_pages, mn->status_change_nid); + mn->nr_pages); break; case MEM_GOING_OFFLINE: break; @@ -358,8 +439,6 @@ static int __meminit page_ext_callback(struct notifier_block *self, return notifier_from_errno(ret); } -#endif - void __init page_ext_init(void) { unsigned long pfn; @@ -396,7 +475,7 @@ void __init page_ext_init(void) cond_resched(); } } - hotplug_memory_notifier(page_ext_callback, 0); + hotplug_memory_notifier(page_ext_callback, DEFAULT_CALLBACK_PRI); pr_info("allocated %ld bytes of page_ext\n", total_usage); invoke_init_callbacks(); return; @@ -410,3 +489,46 @@ void __meminit pgdat_page_ext_init(struct pglist_data *pgdat) } #endif + +/** + * page_ext_get() - Get the extended information for a page. + * @page: The page we're interested in. + * + * Ensures that the page_ext will remain valid until page_ext_put() + * is called. + * + * Return: NULL if no page_ext exists for this page. + * Context: Any context. Caller may not sleep until they have called + * page_ext_put(). + */ +struct page_ext *page_ext_get(struct page *page) +{ + struct page_ext *page_ext; + + rcu_read_lock(); + page_ext = lookup_page_ext(page); + if (!page_ext) { + rcu_read_unlock(); + return NULL; + } + + return page_ext; +} + +/** + * page_ext_put() - Working with page extended information is done. + * @page_ext: Page extended information received from page_ext_get(). + * + * The page extended information of the page may not be valid after this + * function is called. + * + * Return: None. + * Context: Any context with corresponding page_ext_get() is called. + */ +void page_ext_put(struct page_ext *page_ext) +{ + if (unlikely(!page_ext)) + return; + + rcu_read_unlock(); +} |