From 5f79020cb9fea59a5d4d1712bcd320523b129b35 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 28 Sep 2011 12:17:03 +0100 Subject: kmemleak: Show where early_log issues come from Based on initial patch by Steven Rostedt. Early kmemleak warnings did not show where the actual kmemleak API had been called from but rather just a backtrace to the kmemleak_init() function. By having all early kmemleak logs record the stack_trace, we can have kmemleak_init() write exactly where the problem occurred. This patch adds the setting of the kmemleak_warning variable every time a kmemleak warning is issued. The kmemleak_init() function checks this variable during early log replaying and prints the log trace if there was any warning. Reported-by: Steven Rostedt Cc: Andrew Morton Signed-off-by: Catalin Marinas Acked-by: Steven Rostedt --- mm/kmemleak.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) (limited to 'mm') diff --git a/mm/kmemleak.c b/mm/kmemleak.c index f3b2a00fe9c..8b528e3f841 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -196,7 +196,9 @@ static atomic_t kmemleak_enabled = ATOMIC_INIT(0); static atomic_t kmemleak_initialized = ATOMIC_INIT(0); /* enables or disables early logging of the memory operations */ static atomic_t kmemleak_early_log = ATOMIC_INIT(1); -/* set if a fata kmemleak error has occurred */ +/* set if a kmemleak warning was issued */ +static atomic_t kmemleak_warning = ATOMIC_INIT(0); +/* set if a fatal kmemleak error has occurred */ static atomic_t kmemleak_error = ATOMIC_INIT(0); /* minimum and maximum address that may be valid pointers */ @@ -259,9 +261,10 @@ static void kmemleak_disable(void); /* * Print a warning and dump the stack trace. */ -#define kmemleak_warn(x...) do { \ - pr_warning(x); \ - dump_stack(); \ +#define kmemleak_warn(x...) do { \ + pr_warning(x); \ + dump_stack(); \ + atomic_set(&kmemleak_warning, 1); \ } while (0) /* @@ -403,8 +406,8 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) object = prio_tree_entry(node, struct kmemleak_object, tree_node); if (!alias && object->pointer != ptr) { - pr_warning("Found object by alias at 0x%08lx\n", ptr); - dump_stack(); + kmemleak_warn("Found object by alias at 0x%08lx\n", + ptr); dump_object_info(object); object = NULL; } @@ -811,8 +814,7 @@ static void __init log_early(int op_type, const void *ptr, size_t size, log->ptr = ptr; log->size = size; log->min_count = min_count; - if (op_type == KMEMLEAK_ALLOC) - log->trace_len = __save_stack_trace(log->trace); + log->trace_len = __save_stack_trace(log->trace); crt_early_log++; local_irq_restore(flags); } @@ -1659,6 +1661,17 @@ static int kmemleak_boot_config(char *str) } early_param("kmemleak", kmemleak_boot_config); +static void __init print_log_trace(struct early_log *log) +{ + struct stack_trace trace; + + trace.nr_entries = log->trace_len; + trace.entries = log->trace; + + pr_notice("Early log backtrace:\n"); + print_stack_trace(&trace, 2); +} + /* * Kmemleak initialization. */ @@ -1720,7 +1733,13 @@ void __init kmemleak_init(void) kmemleak_no_scan(log->ptr); break; default: - WARN_ON(1); + kmemleak_warn("Unknown early log operation: %d\n", + log->op_type); + } + + if (atomic_read(&kmemleak_warning)) { + print_log_trace(log); + atomic_set(&kmemleak_warning, 0); } } } -- cgit v1.2.3 From b66930052abf2e41b8a978ae265303917cbe6fa0 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 28 Sep 2011 17:22:56 +0100 Subject: kmemleak: When the early log buffer is exceeded, report the actual number Just telling that the early log buffer has been exceeded doesn't mean much. This patch moves the error printing to the kmemleak_init() function and displays the actual calls to the kmemleak API during early logging. Signed-off-by: Catalin Marinas --- mm/kmemleak.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 8b528e3f841..e8c905b70aa 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -797,9 +797,13 @@ static void __init log_early(int op_type, const void *ptr, size_t size, unsigned long flags; struct early_log *log; + if (atomic_read(&kmemleak_error)) { + /* kmemleak stopped recording, just count the requests */ + crt_early_log++; + return; + } + if (crt_early_log >= ARRAY_SIZE(early_log)) { - pr_warning("Early log buffer exceeded, " - "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n"); kmemleak_disable(); return; } @@ -1634,7 +1638,6 @@ static void kmemleak_disable(void) return; /* stop any memory operation tracing */ - atomic_set(&kmemleak_early_log, 0); atomic_set(&kmemleak_enabled, 0); /* check whether it is too early for a kernel thread */ @@ -1694,12 +1697,18 @@ void __init kmemleak_init(void) scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE); INIT_PRIO_TREE_ROOT(&object_tree_root); + if (crt_early_log >= ARRAY_SIZE(early_log)) + pr_warning("Early log buffer exceeded (%d), please increase " + "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log); + /* the kernel is still in UP mode, so disabling the IRQs is enough */ local_irq_save(flags); - if (!atomic_read(&kmemleak_error)) { + atomic_set(&kmemleak_early_log, 0); + if (atomic_read(&kmemleak_error)) { + local_irq_restore(flags); + return; + } else atomic_set(&kmemleak_enabled, 1); - atomic_set(&kmemleak_early_log, 0); - } local_irq_restore(flags); /* -- cgit v1.2.3 From 74341703edca6bc68a165a18453071b097828407 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 29 Sep 2011 11:50:07 +0100 Subject: kmemleak: Report previously found leaks even after an error If an error fatal to kmemleak (like memory allocation failure) happens, kmemleak disables itself but it also removes the access to any previously found memory leaks. This patch allows read-only access to the kmemleak debugfs interface but disables any other action. Reported-by: Nick Bowler Signed-off-by: Catalin Marinas --- mm/kmemleak.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'mm') diff --git a/mm/kmemleak.c b/mm/kmemleak.c index e8c905b70aa..b4f4e6021c1 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1473,9 +1473,6 @@ static const struct seq_operations kmemleak_seq_ops = { static int kmemleak_open(struct inode *inode, struct file *file) { - if (!atomic_read(&kmemleak_enabled)) - return -EBUSY; - return seq_open(file, &kmemleak_seq_ops); } @@ -1549,6 +1546,9 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf, int buf_size; int ret; + if (!atomic_read(&kmemleak_enabled)) + return -EBUSY; + buf_size = min(size, (sizeof(buf) - 1)); if (strncpy_from_user(buf, user_buf, buf_size) < 0) return -EFAULT; @@ -1608,20 +1608,24 @@ static const struct file_operations kmemleak_fops = { }; /* - * Perform the freeing of the kmemleak internal objects after waiting for any - * current memory scan to complete. + * Stop the memory scanning thread and free the kmemleak internal objects if + * no previous scan thread (otherwise, kmemleak may still have some useful + * information on memory leaks). */ static void kmemleak_do_cleanup(struct work_struct *work) { struct kmemleak_object *object; + bool cleanup = scan_thread == NULL; mutex_lock(&scan_mutex); stop_scan_thread(); - rcu_read_lock(); - list_for_each_entry_rcu(object, &object_list, object_list) - delete_object_full(object->pointer); - rcu_read_unlock(); + if (cleanup) { + rcu_read_lock(); + list_for_each_entry_rcu(object, &object_list, object_list) + delete_object_full(object->pointer); + rcu_read_unlock(); + } mutex_unlock(&scan_mutex); } -- cgit v1.2.3 From f528f0b8e53d73b18be71e96693cfab9322f33c7 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 26 Sep 2011 17:12:53 +0100 Subject: kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li Acked-by: Christoph Lameter Acked-by: Tejun Heo Signed-off-by: Catalin Marinas --- mm/kmemleak.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ mm/percpu.c | 12 +++++++++- 2 files changed, 83 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/kmemleak.c b/mm/kmemleak.c index b4f4e6021c1..15c50302ff9 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -230,8 +230,10 @@ static int kmemleak_skip_disable; /* kmemleak operation type for early logging */ enum { KMEMLEAK_ALLOC, + KMEMLEAK_ALLOC_PERCPU, KMEMLEAK_FREE, KMEMLEAK_FREE_PART, + KMEMLEAK_FREE_PERCPU, KMEMLEAK_NOT_LEAK, KMEMLEAK_IGNORE, KMEMLEAK_SCAN_AREA, @@ -852,6 +854,20 @@ out: rcu_read_unlock(); } +/* + * Log an early allocated block and populate the stack trace. + */ +static void early_alloc_percpu(struct early_log *log) +{ + unsigned int cpu; + const void __percpu *ptr = log->ptr; + + for_each_possible_cpu(cpu) { + log->ptr = per_cpu_ptr(ptr, cpu); + early_alloc(log); + } +} + /** * kmemleak_alloc - register a newly allocated object * @ptr: pointer to beginning of the object @@ -878,6 +894,34 @@ void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count, } EXPORT_SYMBOL_GPL(kmemleak_alloc); +/** + * kmemleak_alloc_percpu - register a newly allocated __percpu object + * @ptr: __percpu pointer to beginning of the object + * @size: size of the object + * + * This function is called from the kernel percpu allocator when a new object + * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL + * allocation. + */ +void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size) +{ + unsigned int cpu; + + pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size); + + /* + * Percpu allocations are only scanned and not reported as leaks + * (min_count is set to 0). + */ + if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) + for_each_possible_cpu(cpu) + create_object((unsigned long)per_cpu_ptr(ptr, cpu), + size, 0, GFP_KERNEL); + else if (atomic_read(&kmemleak_early_log)) + log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0); +} +EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu); + /** * kmemleak_free - unregister a previously registered object * @ptr: pointer to beginning of the object @@ -916,6 +960,28 @@ void __ref kmemleak_free_part(const void *ptr, size_t size) } EXPORT_SYMBOL_GPL(kmemleak_free_part); +/** + * kmemleak_free_percpu - unregister a previously registered __percpu object + * @ptr: __percpu pointer to beginning of the object + * + * This function is called from the kernel percpu allocator when an object + * (memory block) is freed (free_percpu). + */ +void __ref kmemleak_free_percpu(const void __percpu *ptr) +{ + unsigned int cpu; + + pr_debug("%s(0x%p)\n", __func__, ptr); + + if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) + for_each_possible_cpu(cpu) + delete_object_full((unsigned long)per_cpu_ptr(ptr, + cpu)); + else if (atomic_read(&kmemleak_early_log)) + log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0); +} +EXPORT_SYMBOL_GPL(kmemleak_free_percpu); + /** * kmemleak_not_leak - mark an allocated object as false positive * @ptr: pointer to beginning of the object @@ -1727,12 +1793,18 @@ void __init kmemleak_init(void) case KMEMLEAK_ALLOC: early_alloc(log); break; + case KMEMLEAK_ALLOC_PERCPU: + early_alloc_percpu(log); + break; case KMEMLEAK_FREE: kmemleak_free(log->ptr); break; case KMEMLEAK_FREE_PART: kmemleak_free_part(log->ptr, log->size); break; + case KMEMLEAK_FREE_PERCPU: + kmemleak_free_percpu(log->ptr); + break; case KMEMLEAK_NOT_LEAK: kmemleak_not_leak(log->ptr); break; diff --git a/mm/percpu.c b/mm/percpu.c index 3bb810a7200..86c5bdbdc37 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -67,6 +67,7 @@ #include #include #include +#include #include #include @@ -710,6 +711,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved) const char *err; int slot, off, new_alloc; unsigned long flags; + void __percpu *ptr; if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) { WARN(true, "illegal size (%zu) or align (%zu) for " @@ -802,7 +804,9 @@ area_found: mutex_unlock(&pcpu_alloc_mutex); /* return address relative to base address */ - return __addr_to_pcpu_ptr(chunk->base_addr + off); + ptr = __addr_to_pcpu_ptr(chunk->base_addr + off); + kmemleak_alloc_percpu(ptr, size); + return ptr; fail_unlock: spin_unlock_irqrestore(&pcpu_lock, flags); @@ -916,6 +920,8 @@ void free_percpu(void __percpu *ptr) if (!ptr) return; + kmemleak_free_percpu(ptr); + addr = __pcpu_ptr_to_addr(ptr); spin_lock_irqsave(&pcpu_lock, flags); @@ -1637,6 +1643,8 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size, rc = -ENOMEM; goto out_free_areas; } + /* kmemleak tracks the percpu allocations separately */ + kmemleak_free(ptr); areas[group] = ptr; base = min(ptr, base); @@ -1751,6 +1759,8 @@ int __init pcpu_page_first_chunk(size_t reserved_size, "for cpu%u\n", psize_str, cpu); goto enomem; } + /* kmemleak tracks the percpu allocations separately */ + kmemleak_free(ptr); pages[j++] = virt_to_page(ptr); } -- cgit v1.2.3 From 029aeff5db879afd7760f11214b6fea45f76b58e Mon Sep 17 00:00:00 2001 From: Laura Abbott Date: Tue, 15 Nov 2011 23:49:09 +0000 Subject: kmemleak: Add support for memory hotplug Ensure that memory hotplug can co-exist with kmemleak by taking the hotplug lock before scanning the memory banks. Signed-off-by: Laura Abbott Signed-off-by: Catalin Marinas --- mm/kmemleak.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 15c50302ff9..c833addd94d 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -100,6 +100,7 @@ #include #include +#include /* * Kmemleak configuration and common defines. @@ -1292,9 +1293,9 @@ static void kmemleak_scan(void) #endif /* - * Struct page scanning for each node. The code below is not yet safe - * with MEMORY_HOTPLUG. + * Struct page scanning for each node. */ + lock_memory_hotplug(); for_each_online_node(i) { pg_data_t *pgdat = NODE_DATA(i); unsigned long start_pfn = pgdat->node_start_pfn; @@ -1313,6 +1314,7 @@ static void kmemleak_scan(void) scan_block(page, page + 1, NULL, 1); } } + unlock_memory_hotplug(); /* * Scanning the task stacks (may introduce false negatives). -- cgit v1.2.3