diff options
Diffstat (limited to 'mm/page_owner.c')
-rw-r--r-- | mm/page_owner.c | 210 |
1 files changed, 206 insertions, 4 deletions
diff --git a/mm/page_owner.c b/mm/page_owner.c index 5634e5d890f8..e7139952ffd9 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -36,6 +36,15 @@ struct page_owner { pid_t free_tgid; }; +struct stack { + struct stack_record *stack_record; + struct stack *next; +}; +static struct stack dummy_stack; +static struct stack failure_stack; +static struct stack *stack_list; +static DEFINE_SPINLOCK(stack_list_lock); + static bool page_owner_enabled __initdata; DEFINE_STATIC_KEY_FALSE(page_owner_inited); @@ -95,6 +104,15 @@ static __init void init_page_owner(void) register_early_stack(); static_branch_enable(&page_owner_inited); init_early_allocated_pages(); + /* Initialize dummy and failure stacks and link them to stack_list */ + dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); + failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle); + if (dummy_stack.stack_record) + refcount_set(&dummy_stack.stack_record->count, 1); + if (failure_stack.stack_record) + refcount_set(&failure_stack.stack_record->count, 1); + dummy_stack.next = &failure_stack; + stack_list = &dummy_stack; } struct page_ext_operations page_owner_ops = { @@ -135,11 +153,74 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags) return handle; } +static void add_stack_record_to_list(struct stack_record *stack_record, + gfp_t gfp_mask) +{ + unsigned long flags; + struct stack *stack; + + /* Filter gfp_mask the same way stackdepot does, for consistency */ + gfp_mask &= ~GFP_ZONEMASK; + gfp_mask &= (GFP_ATOMIC | GFP_KERNEL); + gfp_mask |= __GFP_NOWARN; + + stack = kmalloc(sizeof(*stack), gfp_mask); + if (!stack) + return; + + stack->stack_record = stack_record; + stack->next = NULL; + + spin_lock_irqsave(&stack_list_lock, flags); + stack->next = stack_list; + /* + * This pairs with smp_load_acquire() from function + * stack_start(). This guarantees that stack_start() + * will see an updated stack_list before starting to + * traverse the list. + */ + smp_store_release(&stack_list, stack); + spin_unlock_irqrestore(&stack_list_lock, flags); +} + +static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_mask) +{ + struct stack_record *stack_record = __stack_depot_get_stack_record(handle); + + if (!stack_record) + return; + + /* + * New stack_record's that do not use STACK_DEPOT_FLAG_GET start + * with REFCOUNT_SATURATED to catch spurious increments of their + * refcount. + * Since we do not use STACK_DEPOT_FLAG_GET API, let us + * set a refcount of 1 ourselves. + */ + if (refcount_read(&stack_record->count) == REFCOUNT_SATURATED) { + int old = REFCOUNT_SATURATED; + + if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1)) + /* Add the new stack_record to our list */ + add_stack_record_to_list(stack_record, gfp_mask); + } + refcount_inc(&stack_record->count); +} + +static void dec_stack_record_count(depot_stack_handle_t handle) +{ + struct stack_record *stack_record = __stack_depot_get_stack_record(handle); + + if (stack_record) + refcount_dec(&stack_record->count); +} + void __reset_page_owner(struct page *page, unsigned short order) { int i; struct page_ext *page_ext; depot_stack_handle_t handle; + depot_stack_handle_t alloc_handle; struct page_owner *page_owner; u64 free_ts_nsec = local_clock(); @@ -147,17 +228,29 @@ void __reset_page_owner(struct page *page, unsigned short order) if (unlikely(!page_ext)) return; + page_owner = get_page_owner(page_ext); + alloc_handle = page_owner->handle; + handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); for (i = 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); - page_owner = get_page_owner(page_ext); page_owner->free_handle = handle; page_owner->free_ts_nsec = free_ts_nsec; page_owner->free_pid = current->pid; page_owner->free_tgid = current->tgid; page_ext = page_ext_next(page_ext); + page_owner = get_page_owner(page_ext); } page_ext_put(page_ext); + if (alloc_handle != early_handle) + /* + * early_handle is being set as a handle for all those + * early allocated pages. See init_pages_in_zone(). + * Since their refcount is not being incremented because + * the machinery is not ready yet, we cannot decrement + * their refcount either. + */ + dec_stack_record_count(alloc_handle); } static inline void __set_page_owner_handle(struct page_ext *page_ext, @@ -199,6 +292,7 @@ noinline void __set_page_owner(struct page *page, unsigned short order, return; __set_page_owner_handle(page_ext, handle, order, gfp_mask); page_ext_put(page_ext); + inc_stack_record_count(handle, gfp_mask); } void __set_page_owner_migrate_reason(struct page *page, int reason) @@ -214,7 +308,7 @@ void __set_page_owner_migrate_reason(struct page *page, int reason) page_ext_put(page_ext); } -void __split_page_owner(struct page *page, unsigned int nr) +void __split_page_owner(struct page *page, int old_order, int new_order) { int i; struct page_ext *page_ext = page_ext_get(page); @@ -223,9 +317,9 @@ void __split_page_owner(struct page *page, unsigned int nr) if (unlikely(!page_ext)) return; - for (i = 0; i < nr; i++) { + for (i = 0; i < (1 << old_order); i++) { page_owner = get_page_owner(page_ext); - page_owner->order = 0; + page_owner->order = new_order; page_ext = page_ext_next(page_ext); } page_ext_put(page_ext); @@ -719,8 +813,111 @@ static const struct file_operations proc_page_owner_operations = { .llseek = lseek_page_owner, }; +static void *stack_start(struct seq_file *m, loff_t *ppos) +{ + struct stack *stack; + + if (*ppos == -1UL) + return NULL; + + if (!*ppos) { + /* + * This pairs with smp_store_release() from function + * add_stack_record_to_list(), so we get a consistent + * value of stack_list. + */ + stack = smp_load_acquire(&stack_list); + } else { + stack = m->private; + stack = stack->next; + } + + m->private = stack; + + return stack; +} + +static void *stack_next(struct seq_file *m, void *v, loff_t *ppos) +{ + struct stack *stack = v; + + stack = stack->next; + *ppos = stack ? *ppos + 1 : -1UL; + m->private = stack; + + return stack; +} + +static unsigned long page_owner_stack_threshold; + +static int stack_print(struct seq_file *m, void *v) +{ + int i, stack_count; + struct stack *stack = v; + unsigned long *entries; + unsigned long nr_entries; + struct stack_record *stack_record = stack->stack_record; + + if (!stack->stack_record) + return 0; + + nr_entries = stack_record->size; + entries = stack_record->entries; + stack_count = refcount_read(&stack_record->count) - 1; + + if (stack_count < 1 || stack_count < page_owner_stack_threshold) + return 0; + + for (i = 0; i < nr_entries; i++) + seq_printf(m, " %pS\n", (void *)entries[i]); + seq_printf(m, "stack_count: %d\n\n", stack_count); + + return 0; +} + +static void stack_stop(struct seq_file *m, void *v) +{ +} + +static const struct seq_operations page_owner_stack_op = { + .start = stack_start, + .next = stack_next, + .stop = stack_stop, + .show = stack_print +}; + +static int page_owner_stack_open(struct inode *inode, struct file *file) +{ + return seq_open_private(file, &page_owner_stack_op, 0); +} + +static const struct file_operations page_owner_stack_operations = { + .open = page_owner_stack_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +static int page_owner_threshold_get(void *data, u64 *val) +{ + *val = READ_ONCE(page_owner_stack_threshold); + return 0; +} + +static int page_owner_threshold_set(void *data, u64 val) +{ + WRITE_ONCE(page_owner_stack_threshold, val); + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get, + &page_owner_threshold_set, "%llu"); + + static int __init pageowner_init(void) { + struct dentry *dir; + if (!static_branch_unlikely(&page_owner_inited)) { pr_info("page_owner is disabled\n"); return 0; @@ -728,6 +925,11 @@ static int __init pageowner_init(void) debugfs_create_file("page_owner", 0400, NULL, NULL, &proc_page_owner_operations); + dir = debugfs_create_dir("page_owner_stacks", NULL); + debugfs_create_file("show_stacks", 0400, dir, NULL, + &page_owner_stack_operations); + debugfs_create_file("count_threshold", 0600, dir, NULL, + &proc_page_owner_threshold); return 0; } |