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@@ -0,0 +1,1498 @@
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+/*
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+ * mm/kmemleak.c
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+ *
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+ * Copyright (C) 2008 ARM Limited
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+ * Written by Catalin Marinas <catalin.marinas@arm.com>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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+ *
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+ *
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+ * For more information on the algorithm and kmemleak usage, please see
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+ * Documentation/kmemleak.txt.
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+ *
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+ * Notes on locking
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+ * ----------------
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+ *
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+ * The following locks and mutexes are used by kmemleak:
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+ *
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+ * - kmemleak_lock (rwlock): protects the object_list modifications and
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+ * accesses to the object_tree_root. The object_list is the main list
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+ * holding the metadata (struct kmemleak_object) for the allocated memory
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+ * blocks. The object_tree_root is a priority search tree used to look-up
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+ * metadata based on a pointer to the corresponding memory block. The
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+ * kmemleak_object structures are added to the object_list and
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+ * object_tree_root in the create_object() function called from the
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+ * kmemleak_alloc() callback and removed in delete_object() called from the
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+ * kmemleak_free() callback
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+ * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
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+ * the metadata (e.g. count) are protected by this lock. Note that some
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+ * members of this structure may be protected by other means (atomic or
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+ * kmemleak_lock). This lock is also held when scanning the corresponding
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+ * memory block to avoid the kernel freeing it via the kmemleak_free()
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+ * callback. This is less heavyweight than holding a global lock like
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+ * kmemleak_lock during scanning
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+ * - scan_mutex (mutex): ensures that only one thread may scan the memory for
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+ * unreferenced objects at a time. The gray_list contains the objects which
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+ * are already referenced or marked as false positives and need to be
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+ * scanned. This list is only modified during a scanning episode when the
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+ * scan_mutex is held. At the end of a scan, the gray_list is always empty.
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+ * Note that the kmemleak_object.use_count is incremented when an object is
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+ * added to the gray_list and therefore cannot be freed
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+ * - kmemleak_mutex (mutex): prevents multiple users of the "kmemleak" debugfs
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+ * file together with modifications to the memory scanning parameters
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+ * including the scan_thread pointer
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+ *
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+ * The kmemleak_object structures have a use_count incremented or decremented
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+ * using the get_object()/put_object() functions. When the use_count becomes
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+ * 0, this count can no longer be incremented and put_object() schedules the
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+ * kmemleak_object freeing via an RCU callback. All calls to the get_object()
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+ * function must be protected by rcu_read_lock() to avoid accessing a freed
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+ * structure.
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+ */
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+
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+#include <linux/init.h>
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+#include <linux/kernel.h>
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+#include <linux/list.h>
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+#include <linux/sched.h>
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+#include <linux/jiffies.h>
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+#include <linux/delay.h>
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+#include <linux/module.h>
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+#include <linux/kthread.h>
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+#include <linux/prio_tree.h>
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+#include <linux/gfp.h>
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+#include <linux/fs.h>
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+#include <linux/debugfs.h>
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+#include <linux/seq_file.h>
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+#include <linux/cpumask.h>
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+#include <linux/spinlock.h>
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+#include <linux/mutex.h>
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+#include <linux/rcupdate.h>
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+#include <linux/stacktrace.h>
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+#include <linux/cache.h>
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+#include <linux/percpu.h>
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+#include <linux/hardirq.h>
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+#include <linux/mmzone.h>
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+#include <linux/slab.h>
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+#include <linux/thread_info.h>
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+#include <linux/err.h>
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+#include <linux/uaccess.h>
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+#include <linux/string.h>
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+#include <linux/nodemask.h>
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+#include <linux/mm.h>
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+
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+#include <asm/sections.h>
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+#include <asm/processor.h>
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+#include <asm/atomic.h>
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+
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+#include <linux/kmemleak.h>
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+
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+/*
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+ * Kmemleak configuration and common defines.
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+ */
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+#define MAX_TRACE 16 /* stack trace length */
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+#define REPORTS_NR 50 /* maximum number of reported leaks */
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+#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
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+#define MSECS_SCAN_YIELD 10 /* CPU yielding period */
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+#define SECS_FIRST_SCAN 60 /* delay before the first scan */
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+#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
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+
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+#define BYTES_PER_POINTER sizeof(void *)
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+
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+/* scanning area inside a memory block */
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+struct kmemleak_scan_area {
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+ struct hlist_node node;
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+ unsigned long offset;
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+ size_t length;
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+};
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+
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+/*
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+ * Structure holding the metadata for each allocated memory block.
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+ * Modifications to such objects should be made while holding the
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+ * object->lock. Insertions or deletions from object_list, gray_list or
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+ * tree_node are already protected by the corresponding locks or mutex (see
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+ * the notes on locking above). These objects are reference-counted
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+ * (use_count) and freed using the RCU mechanism.
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+ */
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+struct kmemleak_object {
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+ spinlock_t lock;
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+ unsigned long flags; /* object status flags */
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+ struct list_head object_list;
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+ struct list_head gray_list;
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+ struct prio_tree_node tree_node;
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+ struct rcu_head rcu; /* object_list lockless traversal */
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+ /* object usage count; object freed when use_count == 0 */
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+ atomic_t use_count;
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+ unsigned long pointer;
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+ size_t size;
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+ /* minimum number of a pointers found before it is considered leak */
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+ int min_count;
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+ /* the total number of pointers found pointing to this object */
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+ int count;
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+ /* memory ranges to be scanned inside an object (empty for all) */
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+ struct hlist_head area_list;
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+ unsigned long trace[MAX_TRACE];
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+ unsigned int trace_len;
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+ unsigned long jiffies; /* creation timestamp */
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+ pid_t pid; /* pid of the current task */
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+ char comm[TASK_COMM_LEN]; /* executable name */
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+};
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+
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+/* flag representing the memory block allocation status */
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+#define OBJECT_ALLOCATED (1 << 0)
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+/* flag set after the first reporting of an unreference object */
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+#define OBJECT_REPORTED (1 << 1)
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+/* flag set to not scan the object */
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+#define OBJECT_NO_SCAN (1 << 2)
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+
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+/* the list of all allocated objects */
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+static LIST_HEAD(object_list);
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+/* the list of gray-colored objects (see color_gray comment below) */
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+static LIST_HEAD(gray_list);
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+/* prio search tree for object boundaries */
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+static struct prio_tree_root object_tree_root;
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+/* rw_lock protecting the access to object_list and prio_tree_root */
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+static DEFINE_RWLOCK(kmemleak_lock);
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+
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+/* allocation caches for kmemleak internal data */
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+static struct kmem_cache *object_cache;
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+static struct kmem_cache *scan_area_cache;
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+
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+/* set if tracing memory operations is enabled */
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+static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
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+/* set in the late_initcall if there were no errors */
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+static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
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+/* enables or disables early logging of the memory operations */
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+static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
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+/* set if a fata kmemleak error has occurred */
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+static atomic_t kmemleak_error = ATOMIC_INIT(0);
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+
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+/* minimum and maximum address that may be valid pointers */
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+static unsigned long min_addr = ULONG_MAX;
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+static unsigned long max_addr;
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+
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+/* used for yielding the CPU to other tasks during scanning */
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+static unsigned long next_scan_yield;
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+static struct task_struct *scan_thread;
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+static unsigned long jiffies_scan_yield;
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+static unsigned long jiffies_min_age;
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+/* delay between automatic memory scannings */
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+static signed long jiffies_scan_wait;
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+/* enables or disables the task stacks scanning */
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+static int kmemleak_stack_scan;
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+/* mutex protecting the memory scanning */
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+static DEFINE_MUTEX(scan_mutex);
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+/* mutex protecting the access to the /sys/kernel/debug/kmemleak file */
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+static DEFINE_MUTEX(kmemleak_mutex);
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+
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+/* number of leaks reported (for limitation purposes) */
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+static int reported_leaks;
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+
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+/*
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+ * Early object allocation/freeing logging. Kkmemleak is initialized after the
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+ * kernel allocator. However, both the kernel allocator and kmemleak may
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+ * allocate memory blocks which need to be tracked. Kkmemleak defines an
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+ * arbitrary buffer to hold the allocation/freeing information before it is
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+ * fully initialized.
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+ */
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+
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+/* kmemleak operation type for early logging */
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+enum {
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+ KMEMLEAK_ALLOC,
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+ KMEMLEAK_FREE,
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+ KMEMLEAK_NOT_LEAK,
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+ KMEMLEAK_IGNORE,
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+ KMEMLEAK_SCAN_AREA,
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+ KMEMLEAK_NO_SCAN
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+};
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+
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+/*
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+ * Structure holding the information passed to kmemleak callbacks during the
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+ * early logging.
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+ */
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+struct early_log {
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+ int op_type; /* kmemleak operation type */
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+ const void *ptr; /* allocated/freed memory block */
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+ size_t size; /* memory block size */
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+ int min_count; /* minimum reference count */
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+ unsigned long offset; /* scan area offset */
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+ size_t length; /* scan area length */
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+};
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+
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+/* early logging buffer and current position */
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+static struct early_log early_log[200];
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+static int crt_early_log;
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+
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+static void kmemleak_disable(void);
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+
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+/*
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+ * Print a warning and dump the stack trace.
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+ */
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+#define kmemleak_warn(x...) do { \
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+ pr_warning(x); \
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+ dump_stack(); \
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+} while (0)
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+
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+/*
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+ * Macro invoked when a serious kmemleak condition occured and cannot be
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+ * recovered from. Kkmemleak will be disabled and further allocation/freeing
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+ * tracing no longer available.
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+ */
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+#define kmemleak_panic(x...) do { \
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+ kmemleak_warn(x); \
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+ kmemleak_disable(); \
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+} while (0)
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+
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+/*
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+ * Object colors, encoded with count and min_count:
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+ * - white - orphan object, not enough references to it (count < min_count)
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+ * - gray - not orphan, not marked as false positive (min_count == 0) or
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+ * sufficient references to it (count >= min_count)
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+ * - black - ignore, it doesn't contain references (e.g. text section)
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+ * (min_count == -1). No function defined for this color.
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+ * Newly created objects don't have any color assigned (object->count == -1)
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+ * before the next memory scan when they become white.
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+ */
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+static int color_white(const struct kmemleak_object *object)
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+{
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+ return object->count != -1 && object->count < object->min_count;
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+}
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+
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+static int color_gray(const struct kmemleak_object *object)
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+{
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+ return object->min_count != -1 && object->count >= object->min_count;
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+}
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+
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+/*
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+ * Objects are considered referenced if their color is gray and they have not
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+ * been deleted.
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+ */
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+static int referenced_object(struct kmemleak_object *object)
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+{
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+ return (object->flags & OBJECT_ALLOCATED) && color_gray(object);
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+}
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+
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+/*
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+ * Objects are considered unreferenced only if their color is white, they have
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+ * not be deleted and have a minimum age to avoid false positives caused by
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+ * pointers temporarily stored in CPU registers.
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+ */
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+static int unreferenced_object(struct kmemleak_object *object)
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+{
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+ return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
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+ time_is_before_eq_jiffies(object->jiffies + jiffies_min_age);
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+}
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+
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+/*
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+ * Printing of the (un)referenced objects information, either to the seq file
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+ * or to the kernel log. The print_referenced/print_unreferenced functions
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+ * must be called with the object->lock held.
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+ */
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+#define print_helper(seq, x...) do { \
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+ struct seq_file *s = (seq); \
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+ if (s) \
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+ seq_printf(s, x); \
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+ else \
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+ pr_info(x); \
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+} while (0)
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+
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+static void print_referenced(struct kmemleak_object *object)
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+{
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+ pr_info("kmemleak: referenced object 0x%08lx (size %zu)\n",
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+ object->pointer, object->size);
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+}
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+
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+static void print_unreferenced(struct seq_file *seq,
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+ struct kmemleak_object *object)
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+{
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+ int i;
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+
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+ print_helper(seq, "kmemleak: unreferenced object 0x%08lx (size %zu):\n",
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+ object->pointer, object->size);
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+ print_helper(seq, " comm \"%s\", pid %d, jiffies %lu\n",
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+ object->comm, object->pid, object->jiffies);
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+ print_helper(seq, " backtrace:\n");
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+
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+ for (i = 0; i < object->trace_len; i++) {
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+ void *ptr = (void *)object->trace[i];
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+ print_helper(seq, " [<%p>] %pS\n", ptr, ptr);
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+ }
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+}
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+
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+/*
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+ * Print the kmemleak_object information. This function is used mainly for
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+ * debugging special cases when kmemleak operations. It must be called with
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+ * the object->lock held.
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+ */
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+static void dump_object_info(struct kmemleak_object *object)
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+{
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+ struct stack_trace trace;
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+
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+ trace.nr_entries = object->trace_len;
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+ trace.entries = object->trace;
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+
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+ pr_notice("kmemleak: Object 0x%08lx (size %zu):\n",
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+ object->tree_node.start, object->size);
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+ pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
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+ object->comm, object->pid, object->jiffies);
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+ pr_notice(" min_count = %d\n", object->min_count);
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+ pr_notice(" count = %d\n", object->count);
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+ pr_notice(" backtrace:\n");
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+ print_stack_trace(&trace, 4);
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+}
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+
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+/*
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+ * Look-up a memory block metadata (kmemleak_object) in the priority search
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+ * tree based on a pointer value. If alias is 0, only values pointing to the
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+ * beginning of the memory block are allowed. The kmemleak_lock must be held
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+ * when calling this function.
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+ */
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+static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
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+{
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+ struct prio_tree_node *node;
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+ struct prio_tree_iter iter;
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+ struct kmemleak_object *object;
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+
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+ prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
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+ node = prio_tree_next(&iter);
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+ if (node) {
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+ object = prio_tree_entry(node, struct kmemleak_object,
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+ tree_node);
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+ if (!alias && object->pointer != ptr) {
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+ kmemleak_warn("kmemleak: Found object by alias");
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+ object = NULL;
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+ }
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+ } else
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+ object = NULL;
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+
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+ return object;
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+}
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+
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+/*
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+ * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
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|
|
+ * that once an object's use_count reached 0, the RCU freeing was already
|
|
|
+ * registered and the object should no longer be used. This function must be
|
|
|
+ * called under the protection of rcu_read_lock().
|
|
|
+ */
|
|
|
+static int get_object(struct kmemleak_object *object)
|
|
|
+{
|
|
|
+ return atomic_inc_not_zero(&object->use_count);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * RCU callback to free a kmemleak_object.
|
|
|
+ */
|
|
|
+static void free_object_rcu(struct rcu_head *rcu)
|
|
|
+{
|
|
|
+ struct hlist_node *elem, *tmp;
|
|
|
+ struct kmemleak_scan_area *area;
|
|
|
+ struct kmemleak_object *object =
|
|
|
+ container_of(rcu, struct kmemleak_object, rcu);
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Once use_count is 0 (guaranteed by put_object), there is no other
|
|
|
+ * code accessing this object, hence no need for locking.
|
|
|
+ */
|
|
|
+ hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
|
|
|
+ hlist_del(elem);
|
|
|
+ kmem_cache_free(scan_area_cache, area);
|
|
|
+ }
|
|
|
+ kmem_cache_free(object_cache, object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Decrement the object use_count. Once the count is 0, free the object using
|
|
|
+ * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
|
|
|
+ * delete_object() path, the delayed RCU freeing ensures that there is no
|
|
|
+ * recursive call to the kernel allocator. Lock-less RCU object_list traversal
|
|
|
+ * is also possible.
|
|
|
+ */
|
|
|
+static void put_object(struct kmemleak_object *object)
|
|
|
+{
|
|
|
+ if (!atomic_dec_and_test(&object->use_count))
|
|
|
+ return;
|
|
|
+
|
|
|
+ /* should only get here after delete_object was called */
|
|
|
+ WARN_ON(object->flags & OBJECT_ALLOCATED);
|
|
|
+
|
|
|
+ call_rcu(&object->rcu, free_object_rcu);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Look up an object in the prio search tree and increase its use_count.
|
|
|
+ */
|
|
|
+static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object = NULL;
|
|
|
+
|
|
|
+ rcu_read_lock();
|
|
|
+ read_lock_irqsave(&kmemleak_lock, flags);
|
|
|
+ if (ptr >= min_addr && ptr < max_addr)
|
|
|
+ object = lookup_object(ptr, alias);
|
|
|
+ read_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
+
|
|
|
+ /* check whether the object is still available */
|
|
|
+ if (object && !get_object(object))
|
|
|
+ object = NULL;
|
|
|
+ rcu_read_unlock();
|
|
|
+
|
|
|
+ return object;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Create the metadata (struct kmemleak_object) corresponding to an allocated
|
|
|
+ * memory block and add it to the object_list and object_tree_root.
|
|
|
+ */
|
|
|
+static void create_object(unsigned long ptr, size_t size, int min_count,
|
|
|
+ gfp_t gfp)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+ struct prio_tree_node *node;
|
|
|
+ struct stack_trace trace;
|
|
|
+
|
|
|
+ object = kmem_cache_alloc(object_cache, gfp & ~GFP_SLAB_BUG_MASK);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_panic("kmemleak: Cannot allocate a kmemleak_object "
|
|
|
+ "structure\n");
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ INIT_LIST_HEAD(&object->object_list);
|
|
|
+ INIT_LIST_HEAD(&object->gray_list);
|
|
|
+ INIT_HLIST_HEAD(&object->area_list);
|
|
|
+ spin_lock_init(&object->lock);
|
|
|
+ atomic_set(&object->use_count, 1);
|
|
|
+ object->flags = OBJECT_ALLOCATED;
|
|
|
+ object->pointer = ptr;
|
|
|
+ object->size = size;
|
|
|
+ object->min_count = min_count;
|
|
|
+ object->count = -1; /* no color initially */
|
|
|
+ object->jiffies = jiffies;
|
|
|
+
|
|
|
+ /* task information */
|
|
|
+ if (in_irq()) {
|
|
|
+ object->pid = 0;
|
|
|
+ strncpy(object->comm, "hardirq", sizeof(object->comm));
|
|
|
+ } else if (in_softirq()) {
|
|
|
+ object->pid = 0;
|
|
|
+ strncpy(object->comm, "softirq", sizeof(object->comm));
|
|
|
+ } else {
|
|
|
+ object->pid = current->pid;
|
|
|
+ /*
|
|
|
+ * There is a small chance of a race with set_task_comm(),
|
|
|
+ * however using get_task_comm() here may cause locking
|
|
|
+ * dependency issues with current->alloc_lock. In the worst
|
|
|
+ * case, the command line is not correct.
|
|
|
+ */
|
|
|
+ strncpy(object->comm, current->comm, sizeof(object->comm));
|
|
|
+ }
|
|
|
+
|
|
|
+ /* kernel backtrace */
|
|
|
+ trace.max_entries = MAX_TRACE;
|
|
|
+ trace.nr_entries = 0;
|
|
|
+ trace.entries = object->trace;
|
|
|
+ trace.skip = 1;
|
|
|
+ save_stack_trace(&trace);
|
|
|
+ object->trace_len = trace.nr_entries;
|
|
|
+
|
|
|
+ INIT_PRIO_TREE_NODE(&object->tree_node);
|
|
|
+ object->tree_node.start = ptr;
|
|
|
+ object->tree_node.last = ptr + size - 1;
|
|
|
+
|
|
|
+ write_lock_irqsave(&kmemleak_lock, flags);
|
|
|
+ min_addr = min(min_addr, ptr);
|
|
|
+ max_addr = max(max_addr, ptr + size);
|
|
|
+ node = prio_tree_insert(&object_tree_root, &object->tree_node);
|
|
|
+ /*
|
|
|
+ * The code calling the kernel does not yet have the pointer to the
|
|
|
+ * memory block to be able to free it. However, we still hold the
|
|
|
+ * kmemleak_lock here in case parts of the kernel started freeing
|
|
|
+ * random memory blocks.
|
|
|
+ */
|
|
|
+ if (node != &object->tree_node) {
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ kmemleak_panic("kmemleak: Cannot insert 0x%lx into the object "
|
|
|
+ "search tree (already existing)\n", ptr);
|
|
|
+ object = lookup_object(ptr, 1);
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ dump_object_info(object);
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ list_add_tail_rcu(&object->object_list, &object_list);
|
|
|
+out:
|
|
|
+ write_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Remove the metadata (struct kmemleak_object) for a memory block from the
|
|
|
+ * object_list and object_tree_root and decrement its use_count.
|
|
|
+ */
|
|
|
+static void delete_object(unsigned long ptr)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ write_lock_irqsave(&kmemleak_lock, flags);
|
|
|
+ object = lookup_object(ptr, 0);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_warn("kmemleak: Freeing unknown object at 0x%08lx\n",
|
|
|
+ ptr);
|
|
|
+ write_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+ prio_tree_remove(&object_tree_root, &object->tree_node);
|
|
|
+ list_del_rcu(&object->object_list);
|
|
|
+ write_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
+
|
|
|
+ WARN_ON(!(object->flags & OBJECT_ALLOCATED));
|
|
|
+ WARN_ON(atomic_read(&object->use_count) < 1);
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Locking here also ensures that the corresponding memory block
|
|
|
+ * cannot be freed when it is being scanned.
|
|
|
+ */
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ if (object->flags & OBJECT_REPORTED)
|
|
|
+ print_referenced(object);
|
|
|
+ object->flags &= ~OBJECT_ALLOCATED;
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ put_object(object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Make a object permanently as gray-colored so that it can no longer be
|
|
|
+ * reported as a leak. This is used in general to mark a false positive.
|
|
|
+ */
|
|
|
+static void make_gray_object(unsigned long ptr)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ object = find_and_get_object(ptr, 0);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_warn("kmemleak: Graying unknown object at 0x%08lx\n",
|
|
|
+ ptr);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ object->min_count = 0;
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ put_object(object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Mark the object as black-colored so that it is ignored from scans and
|
|
|
+ * reporting.
|
|
|
+ */
|
|
|
+static void make_black_object(unsigned long ptr)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ object = find_and_get_object(ptr, 0);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_warn("kmemleak: Blacking unknown object at 0x%08lx\n",
|
|
|
+ ptr);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ object->min_count = -1;
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ put_object(object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Add a scanning area to the object. If at least one such area is added,
|
|
|
+ * kmemleak will only scan these ranges rather than the whole memory block.
|
|
|
+ */
|
|
|
+static void add_scan_area(unsigned long ptr, unsigned long offset,
|
|
|
+ size_t length, gfp_t gfp)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+ struct kmemleak_scan_area *area;
|
|
|
+
|
|
|
+ object = find_and_get_object(ptr, 0);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_warn("kmemleak: Adding scan area to unknown "
|
|
|
+ "object at 0x%08lx\n", ptr);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ area = kmem_cache_alloc(scan_area_cache, gfp & ~GFP_SLAB_BUG_MASK);
|
|
|
+ if (!area) {
|
|
|
+ kmemleak_warn("kmemleak: Cannot allocate a scan area\n");
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ if (offset + length > object->size) {
|
|
|
+ kmemleak_warn("kmemleak: Scan area larger than object "
|
|
|
+ "0x%08lx\n", ptr);
|
|
|
+ dump_object_info(object);
|
|
|
+ kmem_cache_free(scan_area_cache, area);
|
|
|
+ goto out_unlock;
|
|
|
+ }
|
|
|
+
|
|
|
+ INIT_HLIST_NODE(&area->node);
|
|
|
+ area->offset = offset;
|
|
|
+ area->length = length;
|
|
|
+
|
|
|
+ hlist_add_head(&area->node, &object->area_list);
|
|
|
+out_unlock:
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+out:
|
|
|
+ put_object(object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
|
|
|
+ * pointer. Such object will not be scanned by kmemleak but references to it
|
|
|
+ * are searched.
|
|
|
+ */
|
|
|
+static void object_no_scan(unsigned long ptr)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ object = find_and_get_object(ptr, 0);
|
|
|
+ if (!object) {
|
|
|
+ kmemleak_warn("kmemleak: Not scanning unknown object at "
|
|
|
+ "0x%08lx\n", ptr);
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ object->flags |= OBJECT_NO_SCAN;
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ put_object(object);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Log an early kmemleak_* call to the early_log buffer. These calls will be
|
|
|
+ * processed later once kmemleak is fully initialized.
|
|
|
+ */
|
|
|
+static void log_early(int op_type, const void *ptr, size_t size,
|
|
|
+ int min_count, unsigned long offset, size_t length)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct early_log *log;
|
|
|
+
|
|
|
+ if (crt_early_log >= ARRAY_SIZE(early_log)) {
|
|
|
+ kmemleak_panic("kmemleak: Early log buffer exceeded\n");
|
|
|
+ return;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * There is no need for locking since the kernel is still in UP mode
|
|
|
+ * at this stage. Disabling the IRQs is enough.
|
|
|
+ */
|
|
|
+ local_irq_save(flags);
|
|
|
+ log = &early_log[crt_early_log];
|
|
|
+ log->op_type = op_type;
|
|
|
+ log->ptr = ptr;
|
|
|
+ log->size = size;
|
|
|
+ log->min_count = min_count;
|
|
|
+ log->offset = offset;
|
|
|
+ log->length = length;
|
|
|
+ crt_early_log++;
|
|
|
+ local_irq_restore(flags);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Memory allocation function callback. This function is called from the
|
|
|
+ * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
|
|
|
+ * vmalloc etc.).
|
|
|
+ */
|
|
|
+void kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ create_object((unsigned long)ptr, size, min_count, gfp);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(kmemleak_alloc);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Memory freeing function callback. This function is called from the kernel
|
|
|
+ * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
|
|
|
+ */
|
|
|
+void kmemleak_free(const void *ptr)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ delete_object((unsigned long)ptr);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL_GPL(kmemleak_free);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Mark an already allocated memory block as a false positive. This will cause
|
|
|
+ * the block to no longer be reported as leak and always be scanned.
|
|
|
+ */
|
|
|
+void kmemleak_not_leak(const void *ptr)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ make_gray_object((unsigned long)ptr);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(kmemleak_not_leak);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Ignore a memory block. This is usually done when it is known that the
|
|
|
+ * corresponding block is not a leak and does not contain any references to
|
|
|
+ * other allocated memory blocks.
|
|
|
+ */
|
|
|
+void kmemleak_ignore(const void *ptr)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ make_black_object((unsigned long)ptr);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(kmemleak_ignore);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Limit the range to be scanned in an allocated memory block.
|
|
|
+ */
|
|
|
+void kmemleak_scan_area(const void *ptr, unsigned long offset, size_t length,
|
|
|
+ gfp_t gfp)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ add_scan_area((unsigned long)ptr, offset, length, gfp);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(kmemleak_scan_area);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Inform kmemleak not to scan the given memory block.
|
|
|
+ */
|
|
|
+void kmemleak_no_scan(const void *ptr)
|
|
|
+{
|
|
|
+ pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
|
+ object_no_scan((unsigned long)ptr);
|
|
|
+ else if (atomic_read(&kmemleak_early_log))
|
|
|
+ log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
|
|
|
+}
|
|
|
+EXPORT_SYMBOL(kmemleak_no_scan);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Yield the CPU so that other tasks get a chance to run. The yielding is
|
|
|
+ * rate-limited to avoid excessive number of calls to the schedule() function
|
|
|
+ * during memory scanning.
|
|
|
+ */
|
|
|
+static void scan_yield(void)
|
|
|
+{
|
|
|
+ might_sleep();
|
|
|
+
|
|
|
+ if (time_is_before_eq_jiffies(next_scan_yield)) {
|
|
|
+ schedule();
|
|
|
+ next_scan_yield = jiffies + jiffies_scan_yield;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Memory scanning is a long process and it needs to be interruptable. This
|
|
|
+ * function checks whether such interrupt condition occured.
|
|
|
+ */
|
|
|
+static int scan_should_stop(void)
|
|
|
+{
|
|
|
+ if (!atomic_read(&kmemleak_enabled))
|
|
|
+ return 1;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * This function may be called from either process or kthread context,
|
|
|
+ * hence the need to check for both stop conditions.
|
|
|
+ */
|
|
|
+ if (current->mm)
|
|
|
+ return signal_pending(current);
|
|
|
+ else
|
|
|
+ return kthread_should_stop();
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Scan a memory block (exclusive range) for valid pointers and add those
|
|
|
+ * found to the gray list.
|
|
|
+ */
|
|
|
+static void scan_block(void *_start, void *_end,
|
|
|
+ struct kmemleak_object *scanned)
|
|
|
+{
|
|
|
+ unsigned long *ptr;
|
|
|
+ unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
|
|
|
+ unsigned long *end = _end - (BYTES_PER_POINTER - 1);
|
|
|
+
|
|
|
+ for (ptr = start; ptr < end; ptr++) {
|
|
|
+ unsigned long flags;
|
|
|
+ unsigned long pointer = *ptr;
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ if (scan_should_stop())
|
|
|
+ break;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * When scanning a memory block with a corresponding
|
|
|
+ * kmemleak_object, the CPU yielding is handled in the calling
|
|
|
+ * code since it holds the object->lock to avoid the block
|
|
|
+ * freeing.
|
|
|
+ */
|
|
|
+ if (!scanned)
|
|
|
+ scan_yield();
|
|
|
+
|
|
|
+ object = find_and_get_object(pointer, 1);
|
|
|
+ if (!object)
|
|
|
+ continue;
|
|
|
+ if (object == scanned) {
|
|
|
+ /* self referenced, ignore */
|
|
|
+ put_object(object);
|
|
|
+ continue;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Avoid the lockdep recursive warning on object->lock being
|
|
|
+ * previously acquired in scan_object(). These locks are
|
|
|
+ * enclosed by scan_mutex.
|
|
|
+ */
|
|
|
+ spin_lock_irqsave_nested(&object->lock, flags,
|
|
|
+ SINGLE_DEPTH_NESTING);
|
|
|
+ if (!color_white(object)) {
|
|
|
+ /* non-orphan, ignored or new */
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ put_object(object);
|
|
|
+ continue;
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Increase the object's reference count (number of pointers
|
|
|
+ * to the memory block). If this count reaches the required
|
|
|
+ * minimum, the object's color will become gray and it will be
|
|
|
+ * added to the gray_list.
|
|
|
+ */
|
|
|
+ object->count++;
|
|
|
+ if (color_gray(object))
|
|
|
+ list_add_tail(&object->gray_list, &gray_list);
|
|
|
+ else
|
|
|
+ put_object(object);
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Scan a memory block corresponding to a kmemleak_object. A condition is
|
|
|
+ * that object->use_count >= 1.
|
|
|
+ */
|
|
|
+static void scan_object(struct kmemleak_object *object)
|
|
|
+{
|
|
|
+ struct kmemleak_scan_area *area;
|
|
|
+ struct hlist_node *elem;
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Once the object->lock is aquired, the corresponding memory block
|
|
|
+ * cannot be freed (the same lock is aquired in delete_object).
|
|
|
+ */
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ if (object->flags & OBJECT_NO_SCAN)
|
|
|
+ goto out;
|
|
|
+ if (!(object->flags & OBJECT_ALLOCATED))
|
|
|
+ /* already freed object */
|
|
|
+ goto out;
|
|
|
+ if (hlist_empty(&object->area_list))
|
|
|
+ scan_block((void *)object->pointer,
|
|
|
+ (void *)(object->pointer + object->size), object);
|
|
|
+ else
|
|
|
+ hlist_for_each_entry(area, elem, &object->area_list, node)
|
|
|
+ scan_block((void *)(object->pointer + area->offset),
|
|
|
+ (void *)(object->pointer + area->offset
|
|
|
+ + area->length), object);
|
|
|
+out:
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Scan data sections and all the referenced memory blocks allocated via the
|
|
|
+ * kernel's standard allocators. This function must be called with the
|
|
|
+ * scan_mutex held.
|
|
|
+ */
|
|
|
+static void kmemleak_scan(void)
|
|
|
+{
|
|
|
+ unsigned long flags;
|
|
|
+ struct kmemleak_object *object, *tmp;
|
|
|
+ struct task_struct *task;
|
|
|
+ int i;
|
|
|
+
|
|
|
+ /* prepare the kmemleak_object's */
|
|
|
+ rcu_read_lock();
|
|
|
+ list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+#ifdef DEBUG
|
|
|
+ /*
|
|
|
+ * With a few exceptions there should be a maximum of
|
|
|
+ * 1 reference to any object at this point.
|
|
|
+ */
|
|
|
+ if (atomic_read(&object->use_count) > 1) {
|
|
|
+ pr_debug("kmemleak: object->use_count = %d\n",
|
|
|
+ atomic_read(&object->use_count));
|
|
|
+ dump_object_info(object);
|
|
|
+ }
|
|
|
+#endif
|
|
|
+ /* reset the reference count (whiten the object) */
|
|
|
+ object->count = 0;
|
|
|
+ if (color_gray(object) && get_object(object))
|
|
|
+ list_add_tail(&object->gray_list, &gray_list);
|
|
|
+
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ }
|
|
|
+ rcu_read_unlock();
|
|
|
+
|
|
|
+ /* data/bss scanning */
|
|
|
+ scan_block(_sdata, _edata, NULL);
|
|
|
+ scan_block(__bss_start, __bss_stop, NULL);
|
|
|
+
|
|
|
+#ifdef CONFIG_SMP
|
|
|
+ /* per-cpu sections scanning */
|
|
|
+ for_each_possible_cpu(i)
|
|
|
+ scan_block(__per_cpu_start + per_cpu_offset(i),
|
|
|
+ __per_cpu_end + per_cpu_offset(i), NULL);
|
|
|
+#endif
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Struct page scanning for each node. The code below is not yet safe
|
|
|
+ * with MEMORY_HOTPLUG.
|
|
|
+ */
|
|
|
+ for_each_online_node(i) {
|
|
|
+ pg_data_t *pgdat = NODE_DATA(i);
|
|
|
+ unsigned long start_pfn = pgdat->node_start_pfn;
|
|
|
+ unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
|
|
|
+ unsigned long pfn;
|
|
|
+
|
|
|
+ for (pfn = start_pfn; pfn < end_pfn; pfn++) {
|
|
|
+ struct page *page;
|
|
|
+
|
|
|
+ if (!pfn_valid(pfn))
|
|
|
+ continue;
|
|
|
+ page = pfn_to_page(pfn);
|
|
|
+ /* only scan if page is in use */
|
|
|
+ if (page_count(page) == 0)
|
|
|
+ continue;
|
|
|
+ scan_block(page, page + 1, NULL);
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Scanning the task stacks may introduce false negatives and it is
|
|
|
+ * not enabled by default.
|
|
|
+ */
|
|
|
+ if (kmemleak_stack_scan) {
|
|
|
+ read_lock(&tasklist_lock);
|
|
|
+ for_each_process(task)
|
|
|
+ scan_block(task_stack_page(task),
|
|
|
+ task_stack_page(task) + THREAD_SIZE, NULL);
|
|
|
+ read_unlock(&tasklist_lock);
|
|
|
+ }
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Scan the objects already referenced from the sections scanned
|
|
|
+ * above. More objects will be referenced and, if there are no memory
|
|
|
+ * leaks, all the objects will be scanned. The list traversal is safe
|
|
|
+ * for both tail additions and removals from inside the loop. The
|
|
|
+ * kmemleak objects cannot be freed from outside the loop because their
|
|
|
+ * use_count was increased.
|
|
|
+ */
|
|
|
+ object = list_entry(gray_list.next, typeof(*object), gray_list);
|
|
|
+ while (&object->gray_list != &gray_list) {
|
|
|
+ scan_yield();
|
|
|
+
|
|
|
+ /* may add new objects to the list */
|
|
|
+ if (!scan_should_stop())
|
|
|
+ scan_object(object);
|
|
|
+
|
|
|
+ tmp = list_entry(object->gray_list.next, typeof(*object),
|
|
|
+ gray_list);
|
|
|
+
|
|
|
+ /* remove the object from the list and release it */
|
|
|
+ list_del(&object->gray_list);
|
|
|
+ put_object(object);
|
|
|
+
|
|
|
+ object = tmp;
|
|
|
+ }
|
|
|
+ WARN_ON(!list_empty(&gray_list));
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Thread function performing automatic memory scanning. Unreferenced objects
|
|
|
+ * at the end of a memory scan are reported but only the first time.
|
|
|
+ */
|
|
|
+static int kmemleak_scan_thread(void *arg)
|
|
|
+{
|
|
|
+ static int first_run = 1;
|
|
|
+
|
|
|
+ pr_info("kmemleak: Automatic memory scanning thread started\n");
|
|
|
+
|
|
|
+ /*
|
|
|
+ * Wait before the first scan to allow the system to fully initialize.
|
|
|
+ */
|
|
|
+ if (first_run) {
|
|
|
+ first_run = 0;
|
|
|
+ ssleep(SECS_FIRST_SCAN);
|
|
|
+ }
|
|
|
+
|
|
|
+ while (!kthread_should_stop()) {
|
|
|
+ struct kmemleak_object *object;
|
|
|
+ signed long timeout = jiffies_scan_wait;
|
|
|
+
|
|
|
+ mutex_lock(&scan_mutex);
|
|
|
+
|
|
|
+ kmemleak_scan();
|
|
|
+ reported_leaks = 0;
|
|
|
+
|
|
|
+ rcu_read_lock();
|
|
|
+ list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ if (reported_leaks >= REPORTS_NR)
|
|
|
+ break;
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ if (!(object->flags & OBJECT_REPORTED) &&
|
|
|
+ unreferenced_object(object)) {
|
|
|
+ print_unreferenced(NULL, object);
|
|
|
+ object->flags |= OBJECT_REPORTED;
|
|
|
+ reported_leaks++;
|
|
|
+ } else if ((object->flags & OBJECT_REPORTED) &&
|
|
|
+ referenced_object(object)) {
|
|
|
+ print_referenced(object);
|
|
|
+ object->flags &= ~OBJECT_REPORTED;
|
|
|
+ }
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ }
|
|
|
+ rcu_read_unlock();
|
|
|
+
|
|
|
+ mutex_unlock(&scan_mutex);
|
|
|
+ /* wait before the next scan */
|
|
|
+ while (timeout && !kthread_should_stop())
|
|
|
+ timeout = schedule_timeout_interruptible(timeout);
|
|
|
+ }
|
|
|
+
|
|
|
+ pr_info("kmemleak: Automatic memory scanning thread ended\n");
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Start the automatic memory scanning thread. This function must be called
|
|
|
+ * with the kmemleak_mutex held.
|
|
|
+ */
|
|
|
+void start_scan_thread(void)
|
|
|
+{
|
|
|
+ if (scan_thread)
|
|
|
+ return;
|
|
|
+ scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
|
|
|
+ if (IS_ERR(scan_thread)) {
|
|
|
+ pr_warning("kmemleak: Failed to create the scan thread\n");
|
|
|
+ scan_thread = NULL;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Stop the automatic memory scanning thread. This function must be called
|
|
|
+ * with the kmemleak_mutex held.
|
|
|
+ */
|
|
|
+void stop_scan_thread(void)
|
|
|
+{
|
|
|
+ if (scan_thread) {
|
|
|
+ kthread_stop(scan_thread);
|
|
|
+ scan_thread = NULL;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Iterate over the object_list and return the first valid object at or after
|
|
|
+ * the required position with its use_count incremented. The function triggers
|
|
|
+ * a memory scanning when the pos argument points to the first position.
|
|
|
+ */
|
|
|
+static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
|
|
|
+{
|
|
|
+ struct kmemleak_object *object;
|
|
|
+ loff_t n = *pos;
|
|
|
+
|
|
|
+ if (!n) {
|
|
|
+ kmemleak_scan();
|
|
|
+ reported_leaks = 0;
|
|
|
+ }
|
|
|
+ if (reported_leaks >= REPORTS_NR)
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ rcu_read_lock();
|
|
|
+ list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
|
+ if (n-- > 0)
|
|
|
+ continue;
|
|
|
+ if (get_object(object))
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ object = NULL;
|
|
|
+out:
|
|
|
+ rcu_read_unlock();
|
|
|
+ return object;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Return the next object in the object_list. The function decrements the
|
|
|
+ * use_count of the previous object and increases that of the next one.
|
|
|
+ */
|
|
|
+static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
|
|
|
+{
|
|
|
+ struct kmemleak_object *prev_obj = v;
|
|
|
+ struct kmemleak_object *next_obj = NULL;
|
|
|
+ struct list_head *n = &prev_obj->object_list;
|
|
|
+
|
|
|
+ ++(*pos);
|
|
|
+ if (reported_leaks >= REPORTS_NR)
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ rcu_read_lock();
|
|
|
+ list_for_each_continue_rcu(n, &object_list) {
|
|
|
+ next_obj = list_entry(n, struct kmemleak_object, object_list);
|
|
|
+ if (get_object(next_obj))
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ rcu_read_unlock();
|
|
|
+out:
|
|
|
+ put_object(prev_obj);
|
|
|
+ return next_obj;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Decrement the use_count of the last object required, if any.
|
|
|
+ */
|
|
|
+static void kmemleak_seq_stop(struct seq_file *seq, void *v)
|
|
|
+{
|
|
|
+ if (v)
|
|
|
+ put_object(v);
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Print the information for an unreferenced object to the seq file.
|
|
|
+ */
|
|
|
+static int kmemleak_seq_show(struct seq_file *seq, void *v)
|
|
|
+{
|
|
|
+ struct kmemleak_object *object = v;
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ spin_lock_irqsave(&object->lock, flags);
|
|
|
+ if (!unreferenced_object(object))
|
|
|
+ goto out;
|
|
|
+ print_unreferenced(seq, object);
|
|
|
+ reported_leaks++;
|
|
|
+out:
|
|
|
+ spin_unlock_irqrestore(&object->lock, flags);
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static const struct seq_operations kmemleak_seq_ops = {
|
|
|
+ .start = kmemleak_seq_start,
|
|
|
+ .next = kmemleak_seq_next,
|
|
|
+ .stop = kmemleak_seq_stop,
|
|
|
+ .show = kmemleak_seq_show,
|
|
|
+};
|
|
|
+
|
|
|
+static int kmemleak_open(struct inode *inode, struct file *file)
|
|
|
+{
|
|
|
+ int ret = 0;
|
|
|
+
|
|
|
+ if (!atomic_read(&kmemleak_enabled))
|
|
|
+ return -EBUSY;
|
|
|
+
|
|
|
+ ret = mutex_lock_interruptible(&kmemleak_mutex);
|
|
|
+ if (ret < 0)
|
|
|
+ goto out;
|
|
|
+ if (file->f_mode & FMODE_READ) {
|
|
|
+ ret = mutex_lock_interruptible(&scan_mutex);
|
|
|
+ if (ret < 0)
|
|
|
+ goto kmemleak_unlock;
|
|
|
+ ret = seq_open(file, &kmemleak_seq_ops);
|
|
|
+ if (ret < 0)
|
|
|
+ goto scan_unlock;
|
|
|
+ }
|
|
|
+ return ret;
|
|
|
+
|
|
|
+scan_unlock:
|
|
|
+ mutex_unlock(&scan_mutex);
|
|
|
+kmemleak_unlock:
|
|
|
+ mutex_unlock(&kmemleak_mutex);
|
|
|
+out:
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+static int kmemleak_release(struct inode *inode, struct file *file)
|
|
|
+{
|
|
|
+ int ret = 0;
|
|
|
+
|
|
|
+ if (file->f_mode & FMODE_READ) {
|
|
|
+ seq_release(inode, file);
|
|
|
+ mutex_unlock(&scan_mutex);
|
|
|
+ }
|
|
|
+ mutex_unlock(&kmemleak_mutex);
|
|
|
+
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * File write operation to configure kmemleak at run-time. The following
|
|
|
+ * commands can be written to the /sys/kernel/debug/kmemleak file:
|
|
|
+ * off - disable kmemleak (irreversible)
|
|
|
+ * stack=on - enable the task stacks scanning
|
|
|
+ * stack=off - disable the tasks stacks scanning
|
|
|
+ * scan=on - start the automatic memory scanning thread
|
|
|
+ * scan=off - stop the automatic memory scanning thread
|
|
|
+ * scan=... - set the automatic memory scanning period in seconds (0 to
|
|
|
+ * disable it)
|
|
|
+ */
|
|
|
+static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
|
|
|
+ size_t size, loff_t *ppos)
|
|
|
+{
|
|
|
+ char buf[64];
|
|
|
+ int buf_size;
|
|
|
+
|
|
|
+ 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;
|
|
|
+ buf[buf_size] = 0;
|
|
|
+
|
|
|
+ if (strncmp(buf, "off", 3) == 0)
|
|
|
+ kmemleak_disable();
|
|
|
+ else if (strncmp(buf, "stack=on", 8) == 0)
|
|
|
+ kmemleak_stack_scan = 1;
|
|
|
+ else if (strncmp(buf, "stack=off", 9) == 0)
|
|
|
+ kmemleak_stack_scan = 0;
|
|
|
+ else if (strncmp(buf, "scan=on", 7) == 0)
|
|
|
+ start_scan_thread();
|
|
|
+ else if (strncmp(buf, "scan=off", 8) == 0)
|
|
|
+ stop_scan_thread();
|
|
|
+ else if (strncmp(buf, "scan=", 5) == 0) {
|
|
|
+ unsigned long secs;
|
|
|
+ int err;
|
|
|
+
|
|
|
+ err = strict_strtoul(buf + 5, 0, &secs);
|
|
|
+ if (err < 0)
|
|
|
+ return err;
|
|
|
+ stop_scan_thread();
|
|
|
+ if (secs) {
|
|
|
+ jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
|
|
|
+ start_scan_thread();
|
|
|
+ }
|
|
|
+ } else
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ /* ignore the rest of the buffer, only one command at a time */
|
|
|
+ *ppos += size;
|
|
|
+ return size;
|
|
|
+}
|
|
|
+
|
|
|
+static const struct file_operations kmemleak_fops = {
|
|
|
+ .owner = THIS_MODULE,
|
|
|
+ .open = kmemleak_open,
|
|
|
+ .read = seq_read,
|
|
|
+ .write = kmemleak_write,
|
|
|
+ .llseek = seq_lseek,
|
|
|
+ .release = kmemleak_release,
|
|
|
+};
|
|
|
+
|
|
|
+/*
|
|
|
+ * Perform the freeing of the kmemleak internal objects after waiting for any
|
|
|
+ * current memory scan to complete.
|
|
|
+ */
|
|
|
+static int kmemleak_cleanup_thread(void *arg)
|
|
|
+{
|
|
|
+ struct kmemleak_object *object;
|
|
|
+
|
|
|
+ mutex_lock(&kmemleak_mutex);
|
|
|
+ stop_scan_thread();
|
|
|
+ mutex_unlock(&kmemleak_mutex);
|
|
|
+
|
|
|
+ mutex_lock(&scan_mutex);
|
|
|
+ rcu_read_lock();
|
|
|
+ list_for_each_entry_rcu(object, &object_list, object_list)
|
|
|
+ delete_object(object->pointer);
|
|
|
+ rcu_read_unlock();
|
|
|
+ mutex_unlock(&scan_mutex);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Start the clean-up thread.
|
|
|
+ */
|
|
|
+static void kmemleak_cleanup(void)
|
|
|
+{
|
|
|
+ struct task_struct *cleanup_thread;
|
|
|
+
|
|
|
+ cleanup_thread = kthread_run(kmemleak_cleanup_thread, NULL,
|
|
|
+ "kmemleak-clean");
|
|
|
+ if (IS_ERR(cleanup_thread))
|
|
|
+ pr_warning("kmemleak: Failed to create the clean-up thread\n");
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Disable kmemleak. No memory allocation/freeing will be traced once this
|
|
|
+ * function is called. Disabling kmemleak is an irreversible operation.
|
|
|
+ */
|
|
|
+static void kmemleak_disable(void)
|
|
|
+{
|
|
|
+ /* atomically check whether it was already invoked */
|
|
|
+ if (atomic_cmpxchg(&kmemleak_error, 0, 1))
|
|
|
+ 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 */
|
|
|
+ if (atomic_read(&kmemleak_initialized))
|
|
|
+ kmemleak_cleanup();
|
|
|
+
|
|
|
+ pr_info("Kernel memory leak detector disabled\n");
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Allow boot-time kmemleak disabling (enabled by default).
|
|
|
+ */
|
|
|
+static int kmemleak_boot_config(char *str)
|
|
|
+{
|
|
|
+ if (!str)
|
|
|
+ return -EINVAL;
|
|
|
+ if (strcmp(str, "off") == 0)
|
|
|
+ kmemleak_disable();
|
|
|
+ else if (strcmp(str, "on") != 0)
|
|
|
+ return -EINVAL;
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+early_param("kmemleak", kmemleak_boot_config);
|
|
|
+
|
|
|
+/*
|
|
|
+ * Kkmemleak initialization.
|
|
|
+ */
|
|
|
+void __init kmemleak_init(void)
|
|
|
+{
|
|
|
+ int i;
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ jiffies_scan_yield = msecs_to_jiffies(MSECS_SCAN_YIELD);
|
|
|
+ jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
|
|
|
+ jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
|
|
|
+
|
|
|
+ object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
|
|
|
+ scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
|
|
|
+ INIT_PRIO_TREE_ROOT(&object_tree_root);
|
|
|
+
|
|
|
+ /* 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_enabled, 1);
|
|
|
+ atomic_set(&kmemleak_early_log, 0);
|
|
|
+ }
|
|
|
+ local_irq_restore(flags);
|
|
|
+
|
|
|
+ /*
|
|
|
+ * This is the point where tracking allocations is safe. Automatic
|
|
|
+ * scanning is started during the late initcall. Add the early logged
|
|
|
+ * callbacks to the kmemleak infrastructure.
|
|
|
+ */
|
|
|
+ for (i = 0; i < crt_early_log; i++) {
|
|
|
+ struct early_log *log = &early_log[i];
|
|
|
+
|
|
|
+ switch (log->op_type) {
|
|
|
+ case KMEMLEAK_ALLOC:
|
|
|
+ kmemleak_alloc(log->ptr, log->size, log->min_count,
|
|
|
+ GFP_KERNEL);
|
|
|
+ break;
|
|
|
+ case KMEMLEAK_FREE:
|
|
|
+ kmemleak_free(log->ptr);
|
|
|
+ break;
|
|
|
+ case KMEMLEAK_NOT_LEAK:
|
|
|
+ kmemleak_not_leak(log->ptr);
|
|
|
+ break;
|
|
|
+ case KMEMLEAK_IGNORE:
|
|
|
+ kmemleak_ignore(log->ptr);
|
|
|
+ break;
|
|
|
+ case KMEMLEAK_SCAN_AREA:
|
|
|
+ kmemleak_scan_area(log->ptr, log->offset, log->length,
|
|
|
+ GFP_KERNEL);
|
|
|
+ break;
|
|
|
+ case KMEMLEAK_NO_SCAN:
|
|
|
+ kmemleak_no_scan(log->ptr);
|
|
|
+ break;
|
|
|
+ default:
|
|
|
+ WARN_ON(1);
|
|
|
+ }
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+/*
|
|
|
+ * Late initialization function.
|
|
|
+ */
|
|
|
+static int __init kmemleak_late_init(void)
|
|
|
+{
|
|
|
+ struct dentry *dentry;
|
|
|
+
|
|
|
+ atomic_set(&kmemleak_initialized, 1);
|
|
|
+
|
|
|
+ if (atomic_read(&kmemleak_error)) {
|
|
|
+ /*
|
|
|
+ * Some error occured and kmemleak was disabled. There is a
|
|
|
+ * small chance that kmemleak_disable() was called immediately
|
|
|
+ * after setting kmemleak_initialized and we may end up with
|
|
|
+ * two clean-up threads but serialized by scan_mutex.
|
|
|
+ */
|
|
|
+ kmemleak_cleanup();
|
|
|
+ return -ENOMEM;
|
|
|
+ }
|
|
|
+
|
|
|
+ dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
|
|
|
+ &kmemleak_fops);
|
|
|
+ if (!dentry)
|
|
|
+ pr_warning("kmemleak: Failed to create the debugfs kmemleak "
|
|
|
+ "file\n");
|
|
|
+ mutex_lock(&kmemleak_mutex);
|
|
|
+ start_scan_thread();
|
|
|
+ mutex_unlock(&kmemleak_mutex);
|
|
|
+
|
|
|
+ pr_info("Kernel memory leak detector initialized\n");
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+late_initcall(kmemleak_late_init);
|
Linus Torvalds