Merge tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux

Kmemleak patches

Main features:
- Handle percpu memory allocations (only scanning them, not actually
  reporting).
- Memory hotplug support.

Usability improvements:
- Show the origin of early allocations.
- Report previously found leaks even if kmemleak has been disabled by
  some error.

* tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux:
  kmemleak: Add support for memory hotplug
  kmemleak: Handle percpu memory allocation
  kmemleak: Report previously found leaks even after an error
  kmemleak: When the early log buffer is exceeded, report the actual number
  kmemleak: Show where early_log issues come from

2 files changed, 143 insertions, 27 deletions

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index f3b2a00fe9c1..c833addd94d7 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -100,6 +100,7 @@
 
 #include <linux/kmemcheck.h>
 #include <linux/kmemleak.h>
+#include <linux/memory_hotplug.h>
 
 /*
  * Kmemleak configuration and common defines.
@@ -196,7 +197,9 @@ 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 */
@@ -228,8 +231,10 @@ 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,
@@ -259,9 +264,10 @@ 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 +409,8 @@ 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;
                 }
@@ -794,9 +800,13 @@ 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;
         }
@@ -811,8 +821,7 @@ 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);
 }
@@ -846,6 +855,20 @@ 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
@@ -873,6 +896,34 @@ 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
  *
@@ -911,6 +962,28 @@ 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
  *
@@ -1220,9 +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;
@@ -1241,6 +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).
@@ -1467,9 +1541,6 @@ 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);
 }
 
@@ -1543,6 +1614,9 @@ 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;
@@ -1602,20 +1676,24 @@ 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);
 }
 
@@ -1632,7 +1710,6 @@ 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 */
@@ -1659,6 +1736,17 @@ 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.
  */
@@ -1681,12 +1769,18 @@ 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);
 
         /*
@@ -1701,12 +1795,18 @@ 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;
@@ -1720,7 +1820,13 @@ 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);
                 }
         }
 }
diff --git a/mm/percpu.c b/mm/percpu.c
index 716eb4acf2fc..f47af9123af7 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -67,6 +67,7 @@
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
+#include <linux/kmemleak.h>
 
 #include <asm/cacheflush.h>
 #include <asm/sections.h>
@@ -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);
@@ -1639,6 +1645,8 @@ 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);
@@ -1753,6 +1761,8 @@ 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);
                 }