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mm/kmemleak.c
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/* * mm/kmemleak.c * * Copyright (C) 2008 ARM Limited * Written by Catalin Marinas <catalin.marinas@arm.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * * For more information on the algorithm and kmemleak usage, please see * Documentation/kmemleak.txt. * * Notes on locking * ---------------- * * The following locks and mutexes are used by kmemleak: * * - kmemleak_lock (rwlock): protects the object_list modifications and * accesses to the object_tree_root. The object_list is the main list * holding the metadata (struct kmemleak_object) for the allocated memory * blocks. The object_tree_root is a priority search tree used to look-up * metadata based on a pointer to the corresponding memory block. The * kmemleak_object structures are added to the object_list and * object_tree_root in the create_object() function called from the * kmemleak_alloc() callback and removed in delete_object() called from the * kmemleak_free() callback * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to * the metadata (e.g. count) are protected by this lock. Note that some * members of this structure may be protected by other means (atomic or * kmemleak_lock). This lock is also held when scanning the corresponding * memory block to avoid the kernel freeing it via the kmemleak_free() * callback. This is less heavyweight than holding a global lock like * kmemleak_lock during scanning * - scan_mutex (mutex): ensures that only one thread may scan the memory for * unreferenced objects at a time. The gray_list contains the objects which * are already referenced or marked as false positives and need to be * scanned. This list is only modified during a scanning episode when the * scan_mutex is held. At the end of a scan, the gray_list is always empty. * 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. This mutex also * prevents multiple users of the "kmemleak" debugfs file together with * modifications to the memory scanning parameters including the scan_thread * pointer |
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* * The kmemleak_object structures have a use_count incremented or decremented * using the get_object()/put_object() functions. When the use_count becomes * 0, this count can no longer be incremented and put_object() schedules the * kmemleak_object freeing via an RCU callback. All calls to the get_object() * function must be protected by rcu_read_lock() to avoid accessing a freed * structure. */ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/init.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/sched.h> #include <linux/jiffies.h> #include <linux/delay.h> |
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#include <linux/export.h> |
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#include <linux/kthread.h> #include <linux/prio_tree.h> |
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#include <linux/fs.h> #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/cpumask.h> #include <linux/spinlock.h> #include <linux/mutex.h> #include <linux/rcupdate.h> #include <linux/stacktrace.h> #include <linux/cache.h> #include <linux/percpu.h> #include <linux/hardirq.h> #include <linux/mmzone.h> #include <linux/slab.h> #include <linux/thread_info.h> #include <linux/err.h> #include <linux/uaccess.h> #include <linux/string.h> #include <linux/nodemask.h> #include <linux/mm.h> |
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#include <linux/workqueue.h> |
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#include <linux/crc32.h> |
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#include <asm/sections.h> #include <asm/processor.h> |
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#include <linux/atomic.h> |
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#include <linux/kmemcheck.h> |
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#include <linux/kmemleak.h> |
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#include <linux/memory_hotplug.h> |
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/* * Kmemleak configuration and common defines. */ #define MAX_TRACE 16 /* stack trace length */ |
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#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ |
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#define SECS_FIRST_SCAN 60 /* delay before the first scan */ #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */ |
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#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */ |
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#define BYTES_PER_POINTER sizeof(void *) |
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/* GFP bitmask for kmemleak internal allocations */ |
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#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \ __GFP_NORETRY | __GFP_NOMEMALLOC | \ __GFP_NOWARN) |
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/* scanning area inside a memory block */ struct kmemleak_scan_area { struct hlist_node node; |
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unsigned long start; size_t size; |
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}; |
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#define KMEMLEAK_GREY 0 #define KMEMLEAK_BLACK -1 |
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/* * Structure holding the metadata for each allocated memory block. * Modifications to such objects should be made while holding the * object->lock. Insertions or deletions from object_list, gray_list or * tree_node are already protected by the corresponding locks or mutex (see * the notes on locking above). These objects are reference-counted * (use_count) and freed using the RCU mechanism. */ struct kmemleak_object { spinlock_t lock; unsigned long flags; /* object status flags */ struct list_head object_list; struct list_head gray_list; struct prio_tree_node tree_node; struct rcu_head rcu; /* object_list lockless traversal */ /* object usage count; object freed when use_count == 0 */ atomic_t use_count; unsigned long pointer; size_t size; /* minimum number of a pointers found before it is considered leak */ int min_count; /* the total number of pointers found pointing to this object */ int count; |
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/* checksum for detecting modified objects */ u32 checksum; |
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/* memory ranges to be scanned inside an object (empty for all) */ struct hlist_head area_list; unsigned long trace[MAX_TRACE]; unsigned int trace_len; unsigned long jiffies; /* creation timestamp */ pid_t pid; /* pid of the current task */ char comm[TASK_COMM_LEN]; /* executable name */ }; /* flag representing the memory block allocation status */ #define OBJECT_ALLOCATED (1 << 0) /* flag set after the first reporting of an unreference object */ #define OBJECT_REPORTED (1 << 1) /* flag set to not scan the object */ #define OBJECT_NO_SCAN (1 << 2) |
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/* number of bytes to print per line; must be 16 or 32 */ #define HEX_ROW_SIZE 16 /* number of bytes to print at a time (1, 2, 4, 8) */ #define HEX_GROUP_SIZE 1 /* include ASCII after the hex output */ #define HEX_ASCII 1 /* max number of lines to be printed */ #define HEX_MAX_LINES 2 |
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/* the list of all allocated objects */ static LIST_HEAD(object_list); /* the list of gray-colored objects (see color_gray comment below) */ static LIST_HEAD(gray_list); /* prio search tree for object boundaries */ static struct prio_tree_root object_tree_root; /* rw_lock protecting the access to object_list and prio_tree_root */ static DEFINE_RWLOCK(kmemleak_lock); /* allocation caches for kmemleak internal data */ static struct kmem_cache *object_cache; static struct kmem_cache *scan_area_cache; /* set if tracing memory operations is enabled */ static atomic_t kmemleak_enabled = ATOMIC_INIT(0); /* set in the late_initcall if there were no errors */ 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); |
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/* set if a kmemleak warning was issued */ static atomic_t kmemleak_warning = ATOMIC_INIT(0); /* set if a fatal kmemleak error has occurred */ |
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static atomic_t kmemleak_error = ATOMIC_INIT(0); /* minimum and maximum address that may be valid pointers */ static unsigned long min_addr = ULONG_MAX; static unsigned long max_addr; |
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static struct task_struct *scan_thread; |
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/* used to avoid reporting of recently allocated objects */ |
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static unsigned long jiffies_min_age; |
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static unsigned long jiffies_last_scan; |
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/* delay between automatic memory scannings */ static signed long jiffies_scan_wait; /* enables or disables the task stacks scanning */ |
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static int kmemleak_stack_scan = 1; |
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/* protects the memory scanning, parameters and debug/kmemleak file access */ |
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static DEFINE_MUTEX(scan_mutex); |
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/* setting kmemleak=on, will set this var, skipping the disable */ static int kmemleak_skip_disable; |
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/* |
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* Early object allocation/freeing logging. Kmemleak 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. Kmemleak defines an |
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* arbitrary buffer to hold the allocation/freeing information before it is * fully initialized. */ /* kmemleak operation type for early logging */ enum { KMEMLEAK_ALLOC, |
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KMEMLEAK_ALLOC_PERCPU, |
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KMEMLEAK_FREE, |
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KMEMLEAK_FREE_PART, |
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KMEMLEAK_FREE_PERCPU, |
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KMEMLEAK_NOT_LEAK, KMEMLEAK_IGNORE, KMEMLEAK_SCAN_AREA, KMEMLEAK_NO_SCAN }; /* * Structure holding the information passed to kmemleak callbacks during the * early logging. */ struct early_log { int op_type; /* kmemleak operation type */ const void *ptr; /* allocated/freed memory block */ size_t size; /* memory block size */ int min_count; /* minimum reference count */ |
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unsigned long trace[MAX_TRACE]; /* stack trace */ unsigned int trace_len; /* stack trace length */ |
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}; /* early logging buffer and current position */ |
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static struct early_log early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata; static int crt_early_log __initdata; |
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static void kmemleak_disable(void); /* * Print a warning and dump the stack trace. */ |
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#define kmemleak_warn(x...) do { \ pr_warning(x); \ dump_stack(); \ atomic_set(&kmemleak_warning, 1); \ |
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} while (0) /* |
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* Macro invoked when a serious kmemleak condition occurred and cannot be |
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* recovered from. Kmemleak will be disabled and further allocation/freeing |
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* tracing no longer available. */ |
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#define kmemleak_stop(x...) do { \ |
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kmemleak_warn(x); \ kmemleak_disable(); \ } while (0) /* |
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* Printing of the objects hex dump to the seq file. The number of lines to be * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called * with the object->lock held. */ static void hex_dump_object(struct seq_file *seq, struct kmemleak_object *object) { const u8 *ptr = (const u8 *)object->pointer; int i, len, remaining; unsigned char linebuf[HEX_ROW_SIZE * 5]; /* limit the number of lines to HEX_MAX_LINES */ remaining = len = min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE)); seq_printf(seq, " hex dump (first %d bytes): ", len); for (i = 0; i < len; i += HEX_ROW_SIZE) { int linelen = min(remaining, HEX_ROW_SIZE); remaining -= HEX_ROW_SIZE; hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE, HEX_GROUP_SIZE, linebuf, sizeof(linebuf), HEX_ASCII); seq_printf(seq, " %s ", linebuf); } } /* |
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* Object colors, encoded with count and min_count: * - white - orphan object, not enough references to it (count < min_count) * - gray - not orphan, not marked as false positive (min_count == 0) or * sufficient references to it (count >= min_count) * - black - ignore, it doesn't contain references (e.g. text section) * (min_count == -1). No function defined for this color. * Newly created objects don't have any color assigned (object->count == -1) * before the next memory scan when they become white. */ |
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static bool color_white(const struct kmemleak_object *object) |
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{ |
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return object->count != KMEMLEAK_BLACK && object->count < object->min_count; |
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} |
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static bool color_gray(const struct kmemleak_object *object) |
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{ |
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return object->min_count != KMEMLEAK_BLACK && object->count >= object->min_count; |
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} /* |
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* Objects are considered unreferenced only if their color is white, they have * not be deleted and have a minimum age to avoid false positives caused by * pointers temporarily stored in CPU registers. */ |
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static bool unreferenced_object(struct kmemleak_object *object) |
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{ |
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return (color_white(object) && object->flags & OBJECT_ALLOCATED) && |
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time_before_eq(object->jiffies + jiffies_min_age, jiffies_last_scan); |
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} /* |
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* Printing of the unreferenced objects information to the seq file. The * print_unreferenced function must be called with the object->lock held. |
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*/ |
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static void print_unreferenced(struct seq_file *seq, struct kmemleak_object *object) { int i; |
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unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies); |
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seq_printf(seq, "unreferenced object 0x%08lx (size %zu): ", object->pointer, object->size); |
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seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds) ", object->comm, object->pid, object->jiffies, msecs_age / 1000, msecs_age % 1000); |
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hex_dump_object(seq, object); |
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seq_printf(seq, " backtrace: "); |
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for (i = 0; i < object->trace_len; i++) { void *ptr = (void *)object->trace[i]; |
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seq_printf(seq, " [<%p>] %pS ", ptr, ptr); |
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} } /* * Print the kmemleak_object information. This function is used mainly for * debugging special cases when kmemleak operations. It must be called with * the object->lock held. */ static void dump_object_info(struct kmemleak_object *object) { struct stack_trace trace; trace.nr_entries = object->trace_len; trace.entries = object->trace; |
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pr_notice("Object 0x%08lx (size %zu): ", |
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object->tree_node.start, object->size); pr_notice(" comm \"%s\", pid %d, jiffies %lu ", object->comm, object->pid, object->jiffies); pr_notice(" min_count = %d ", object->min_count); pr_notice(" count = %d ", object->count); |
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pr_notice(" flags = 0x%lx ", object->flags); |
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pr_notice(" checksum = %d ", object->checksum); |
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pr_notice(" backtrace: "); print_stack_trace(&trace, 4); } /* * Look-up a memory block metadata (kmemleak_object) in the priority search * tree based on a pointer value. If alias is 0, only values pointing to the * beginning of the memory block are allowed. The kmemleak_lock must be held * when calling this function. */ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) { struct prio_tree_node *node; struct prio_tree_iter iter; struct kmemleak_object *object; prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr); node = prio_tree_next(&iter); if (node) { object = prio_tree_entry(node, struct kmemleak_object, tree_node); if (!alias && object->pointer != ptr) { |
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kmemleak_warn("Found object by alias at 0x%08lx ", ptr); |
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dump_object_info(object); |
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object = NULL; } } else object = NULL; return object; } /* * Increment the object use_count. Return 1 if successful or 0 otherwise. Note * 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; } /* |
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* Save stack trace to the given array of MAX_TRACE size. */ static int __save_stack_trace(unsigned long *trace) { struct stack_trace stack_trace; stack_trace.max_entries = MAX_TRACE; stack_trace.nr_entries = 0; stack_trace.entries = trace; stack_trace.skip = 2; save_stack_trace(&stack_trace); return stack_trace.nr_entries; } /* |
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* Create the metadata (struct kmemleak_object) corresponding to an allocated * memory block and add it to the object_list and object_tree_root. */ |
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static struct kmemleak_object *create_object(unsigned long ptr, size_t size, int min_count, gfp_t gfp) |
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{ unsigned long flags; struct kmemleak_object *object; struct prio_tree_node *node; |
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object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp)); |
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if (!object) { |
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pr_warning("Cannot allocate a kmemleak_object structure "); kmemleak_disable(); |
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return NULL; |
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} 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); |
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object->flags = OBJECT_ALLOCATED; |
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object->pointer = ptr; object->size = size; object->min_count = min_count; |
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object->count = 0; /* white color initially */ |
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object->jiffies = jiffies; |
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object->checksum = 0; |
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/* 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 */ |
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object->trace_len = __save_stack_trace(object->trace); |
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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); |
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573 574 575 576 577 578 579 580 581 582 |
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) { |
ae281064b
|
583 584 585 |
kmemleak_stop("Cannot insert 0x%lx into the object search tree " "(already existing) ", ptr); |
3c7b4e6b8
|
586 |
object = lookup_object(ptr, 1); |
0580a1819
|
587 |
spin_lock(&object->lock); |
3c7b4e6b8
|
588 |
dump_object_info(object); |
0580a1819
|
589 |
spin_unlock(&object->lock); |
3c7b4e6b8
|
590 591 592 593 594 595 |
goto out; } list_add_tail_rcu(&object->object_list, &object_list); out: write_unlock_irqrestore(&kmemleak_lock, flags); |
fd6789675
|
596 |
return object; |
3c7b4e6b8
|
597 598 599 600 601 602 |
} /* * Remove the metadata (struct kmemleak_object) for a memory block from the * object_list and object_tree_root and decrement its use_count. */ |
53238a60d
|
603 |
static void __delete_object(struct kmemleak_object *object) |
3c7b4e6b8
|
604 605 |
{ unsigned long flags; |
3c7b4e6b8
|
606 607 |
write_lock_irqsave(&kmemleak_lock, flags); |
3c7b4e6b8
|
608 609 610 611 612 |
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)); |
53238a60d
|
613 |
WARN_ON(atomic_read(&object->use_count) < 2); |
3c7b4e6b8
|
614 615 616 617 618 619 |
/* * Locking here also ensures that the corresponding memory block * cannot be freed when it is being scanned. */ spin_lock_irqsave(&object->lock, flags); |
3c7b4e6b8
|
620 621 622 623 624 625 |
object->flags &= ~OBJECT_ALLOCATED; spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /* |
53238a60d
|
626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 |
* Look up the metadata (struct kmemleak_object) corresponding to ptr and * delete it. */ static void delete_object_full(unsigned long ptr) { struct kmemleak_object *object; object = find_and_get_object(ptr, 0); if (!object) { #ifdef DEBUG kmemleak_warn("Freeing unknown object at 0x%08lx ", ptr); #endif return; } __delete_object(object); put_object(object); } /* * Look up the metadata (struct kmemleak_object) corresponding to ptr and * delete it. If the memory block is partially freed, the function may create * additional metadata for the remaining parts of the block. */ static void delete_object_part(unsigned long ptr, size_t size) { struct kmemleak_object *object; unsigned long start, end; object = find_and_get_object(ptr, 1); if (!object) { #ifdef DEBUG kmemleak_warn("Partially freeing unknown object at 0x%08lx " "(size %zu) ", ptr, size); #endif return; } __delete_object(object); /* * Create one or two objects that may result from the memory block * split. Note that partial freeing is only done by free_bootmem() and * this happens before kmemleak_init() is called. The path below is * only executed during early log recording in kmemleak_init(), so * GFP_KERNEL is enough. */ start = object->pointer; end = object->pointer + object->size; if (ptr > start) create_object(start, ptr - start, object->min_count, GFP_KERNEL); if (ptr + size < end) create_object(ptr + size, end - ptr - size, object->min_count, GFP_KERNEL); put_object(object); } |
a1084c877
|
685 686 687 688 689 690 691 692 693 |
static void __paint_it(struct kmemleak_object *object, int color) { object->min_count = color; if (color == KMEMLEAK_BLACK) object->flags |= OBJECT_NO_SCAN; } static void paint_it(struct kmemleak_object *object, int color) |
3c7b4e6b8
|
694 695 |
{ unsigned long flags; |
a1084c877
|
696 697 698 699 700 701 702 703 |
spin_lock_irqsave(&object->lock, flags); __paint_it(object, color); spin_unlock_irqrestore(&object->lock, flags); } static void paint_ptr(unsigned long ptr, int color) { |
3c7b4e6b8
|
704 705 706 707 |
struct kmemleak_object *object; object = find_and_get_object(ptr, 0); if (!object) { |
a1084c877
|
708 709 710 711 712 |
kmemleak_warn("Trying to color unknown object " "at 0x%08lx as %s ", ptr, (color == KMEMLEAK_GREY) ? "Grey" : (color == KMEMLEAK_BLACK) ? "Black" : "Unknown"); |
3c7b4e6b8
|
713 714 |
return; } |
a1084c877
|
715 |
paint_it(object, color); |
3c7b4e6b8
|
716 717 718 719 |
put_object(object); } /* |
145b64b95
|
720 |
* Mark an object permanently as gray-colored so that it can no longer be |
a1084c877
|
721 722 723 724 725 726 727 728 |
* reported as a leak. This is used in general to mark a false positive. */ static void make_gray_object(unsigned long ptr) { paint_ptr(ptr, KMEMLEAK_GREY); } /* |
3c7b4e6b8
|
729 730 731 732 733 |
* Mark the object as black-colored so that it is ignored from scans and * reporting. */ static void make_black_object(unsigned long ptr) { |
a1084c877
|
734 |
paint_ptr(ptr, KMEMLEAK_BLACK); |
3c7b4e6b8
|
735 736 737 738 739 740 |
} /* * 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. */ |
c017b4be3
|
741 |
static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) |
3c7b4e6b8
|
742 743 744 745 |
{ unsigned long flags; struct kmemleak_object *object; struct kmemleak_scan_area *area; |
c017b4be3
|
746 |
object = find_and_get_object(ptr, 1); |
3c7b4e6b8
|
747 |
if (!object) { |
ae281064b
|
748 749 750 |
kmemleak_warn("Adding scan area to unknown object at 0x%08lx ", ptr); |
3c7b4e6b8
|
751 752 |
return; } |
6ae4bd1f0
|
753 |
area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp)); |
3c7b4e6b8
|
754 |
if (!area) { |
6ae4bd1f0
|
755 756 |
pr_warning("Cannot allocate a scan area "); |
3c7b4e6b8
|
757 758 759 760 |
goto out; } spin_lock_irqsave(&object->lock, flags); |
c017b4be3
|
761 |
if (ptr + size > object->pointer + object->size) { |
ae281064b
|
762 763 |
kmemleak_warn("Scan area larger than object 0x%08lx ", ptr); |
3c7b4e6b8
|
764 765 766 767 768 769 |
dump_object_info(object); kmem_cache_free(scan_area_cache, area); goto out_unlock; } INIT_HLIST_NODE(&area->node); |
c017b4be3
|
770 771 |
area->start = ptr; area->size = size; |
3c7b4e6b8
|
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 |
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) { |
ae281064b
|
792 793 |
kmemleak_warn("Not scanning unknown object at 0x%08lx ", ptr); |
3c7b4e6b8
|
794 795 796 797 798 799 800 801 802 803 804 805 806 |
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. */ |
a6186d89c
|
807 |
static void __init log_early(int op_type, const void *ptr, size_t size, |
c017b4be3
|
808 |
int min_count) |
3c7b4e6b8
|
809 810 811 |
{ unsigned long flags; struct early_log *log; |
b66930052
|
812 813 814 815 816 |
if (atomic_read(&kmemleak_error)) { /* kmemleak stopped recording, just count the requests */ crt_early_log++; return; } |
3c7b4e6b8
|
817 |
if (crt_early_log >= ARRAY_SIZE(early_log)) { |
a9d9058ab
|
818 |
kmemleak_disable(); |
3c7b4e6b8
|
819 820 821 822 823 824 825 826 827 828 829 830 831 |
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; |
5f79020cb
|
832 |
log->trace_len = __save_stack_trace(log->trace); |
3c7b4e6b8
|
833 834 835 836 837 |
crt_early_log++; local_irq_restore(flags); } /* |
fd6789675
|
838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 |
* Log an early allocated block and populate the stack trace. */ static void early_alloc(struct early_log *log) { struct kmemleak_object *object; unsigned long flags; int i; if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr)) return; /* * RCU locking needed to ensure object is not freed via put_object(). */ rcu_read_lock(); object = create_object((unsigned long)log->ptr, log->size, |
c1bcd6b32
|
854 |
log->min_count, GFP_ATOMIC); |
0d5d1aadc
|
855 856 |
if (!object) goto out; |
fd6789675
|
857 858 859 860 861 |
spin_lock_irqsave(&object->lock, flags); for (i = 0; i < log->trace_len; i++) object->trace[i] = log->trace[i]; object->trace_len = log->trace_len; spin_unlock_irqrestore(&object->lock, flags); |
0d5d1aadc
|
862 |
out: |
fd6789675
|
863 864 |
rcu_read_unlock(); } |
f528f0b8e
|
865 866 867 868 869 870 871 872 873 874 875 876 877 |
/* * 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); } } |
a2b6bf63c
|
878 879 880 881 882 883 884 885 886 887 888 889 890 |
/** * kmemleak_alloc - register a newly allocated object * @ptr: pointer to beginning of the object * @size: size of the object * @min_count: minimum number of references to this object. If during memory * scanning a number of references less than @min_count is found, * the object is reported as a memory leak. If @min_count is 0, * the object is never reported as a leak. If @min_count is -1, * the object is ignored (not scanned and not reported as a leak) * @gfp: kmalloc() flags used for kmemleak internal memory allocations * * This function is called from the kernel allocators when a new object * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.). |
3c7b4e6b8
|
891 |
*/ |
a6186d89c
|
892 893 |
void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp) |
3c7b4e6b8
|
894 895 896 897 898 899 900 |
{ pr_debug("%s(0x%p, %zu, %d) ", __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)) |
c017b4be3
|
901 |
log_early(KMEMLEAK_ALLOC, ptr, size, min_count); |
3c7b4e6b8
|
902 903 |
} EXPORT_SYMBOL_GPL(kmemleak_alloc); |
a2b6bf63c
|
904 |
/** |
f528f0b8e
|
905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 |
* 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) ", __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); /** |
a2b6bf63c
|
934 935 936 937 938 |
* kmemleak_free - unregister a previously registered object * @ptr: pointer to beginning of the object * * This function is called from the kernel allocators when an object (memory * block) is freed (kmem_cache_free, kfree, vfree etc.). |
3c7b4e6b8
|
939 |
*/ |
a6186d89c
|
940 |
void __ref kmemleak_free(const void *ptr) |
3c7b4e6b8
|
941 942 943 944 945 |
{ pr_debug("%s(0x%p) ", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) |
53238a60d
|
946 |
delete_object_full((unsigned long)ptr); |
3c7b4e6b8
|
947 |
else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
948 |
log_early(KMEMLEAK_FREE, ptr, 0, 0); |
3c7b4e6b8
|
949 950 |
} EXPORT_SYMBOL_GPL(kmemleak_free); |
a2b6bf63c
|
951 952 953 954 955 956 957 958 |
/** * kmemleak_free_part - partially unregister a previously registered object * @ptr: pointer to the beginning or inside the object. This also * represents the start of the range to be freed * @size: size to be unregistered * * This function is called when only a part of a memory block is freed * (usually from the bootmem allocator). |
53238a60d
|
959 |
*/ |
a6186d89c
|
960 |
void __ref kmemleak_free_part(const void *ptr, size_t size) |
53238a60d
|
961 962 963 964 965 966 967 |
{ pr_debug("%s(0x%p) ", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) delete_object_part((unsigned long)ptr, size); else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
968 |
log_early(KMEMLEAK_FREE_PART, ptr, size, 0); |
53238a60d
|
969 970 |
} EXPORT_SYMBOL_GPL(kmemleak_free_part); |
a2b6bf63c
|
971 |
/** |
f528f0b8e
|
972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 |
* 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) ", __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); /** |
a2b6bf63c
|
995 996 997 998 999 |
* kmemleak_not_leak - mark an allocated object as false positive * @ptr: pointer to beginning of the object * * Calling this function on an object will cause the memory block to no longer * be reported as leak and always be scanned. |
3c7b4e6b8
|
1000 |
*/ |
a6186d89c
|
1001 |
void __ref kmemleak_not_leak(const void *ptr) |
3c7b4e6b8
|
1002 1003 1004 1005 1006 1007 1008 |
{ pr_debug("%s(0x%p) ", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) make_gray_object((unsigned long)ptr); else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
1009 |
log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0); |
3c7b4e6b8
|
1010 1011 |
} EXPORT_SYMBOL(kmemleak_not_leak); |
a2b6bf63c
|
1012 1013 1014 1015 1016 1017 1018 1019 |
/** * kmemleak_ignore - ignore an allocated object * @ptr: pointer to beginning of the object * * Calling this function on an object will cause the memory block to be * ignored (not scanned and not reported as a leak). 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. |
3c7b4e6b8
|
1020 |
*/ |
a6186d89c
|
1021 |
void __ref kmemleak_ignore(const void *ptr) |
3c7b4e6b8
|
1022 1023 1024 1025 1026 1027 1028 |
{ pr_debug("%s(0x%p) ", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) make_black_object((unsigned long)ptr); else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
1029 |
log_early(KMEMLEAK_IGNORE, ptr, 0, 0); |
3c7b4e6b8
|
1030 1031 |
} EXPORT_SYMBOL(kmemleak_ignore); |
a2b6bf63c
|
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 |
/** * kmemleak_scan_area - limit the range to be scanned in an allocated object * @ptr: pointer to beginning or inside the object. This also * represents the start of the scan area * @size: size of the scan area * @gfp: kmalloc() flags used for kmemleak internal memory allocations * * This function is used when it is known that only certain parts of an object * contain references to other objects. Kmemleak will only scan these areas * reducing the number false negatives. |
3c7b4e6b8
|
1042 |
*/ |
c017b4be3
|
1043 |
void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp) |
3c7b4e6b8
|
1044 1045 1046 |
{ pr_debug("%s(0x%p) ", __func__, ptr); |
b469d4329
|
1047 |
if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr)) |
c017b4be3
|
1048 |
add_scan_area((unsigned long)ptr, size, gfp); |
3c7b4e6b8
|
1049 |
else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
1050 |
log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0); |
3c7b4e6b8
|
1051 1052 |
} EXPORT_SYMBOL(kmemleak_scan_area); |
a2b6bf63c
|
1053 1054 1055 1056 1057 1058 1059 1060 |
/** * kmemleak_no_scan - do not scan an allocated object * @ptr: pointer to beginning of the object * * This function notifies kmemleak not to scan the given memory block. Useful * in situations where it is known that the given object does not contain any * references to other objects. Kmemleak will not scan such objects reducing * the number of false negatives. |
3c7b4e6b8
|
1061 |
*/ |
a6186d89c
|
1062 |
void __ref kmemleak_no_scan(const void *ptr) |
3c7b4e6b8
|
1063 1064 1065 1066 1067 1068 1069 |
{ pr_debug("%s(0x%p) ", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) object_no_scan((unsigned long)ptr); else if (atomic_read(&kmemleak_early_log)) |
c017b4be3
|
1070 |
log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0); |
3c7b4e6b8
|
1071 1072 1073 1074 |
} EXPORT_SYMBOL(kmemleak_no_scan); /* |
04609ccc4
|
1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 |
* Update an object's checksum and return true if it was modified. */ static bool update_checksum(struct kmemleak_object *object) { u32 old_csum = object->checksum; if (!kmemcheck_is_obj_initialized(object->pointer, object->size)) return false; object->checksum = crc32(0, (void *)object->pointer, object->size); return object->checksum != old_csum; } /* |
3c7b4e6b8
|
1089 |
* Memory scanning is a long process and it needs to be interruptable. This |
25985edce
|
1090 |
* function checks whether such interrupt condition occurred. |
3c7b4e6b8
|
1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 |
*/ 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, |
4b8a96744
|
1114 |
struct kmemleak_object *scanned, int allow_resched) |
3c7b4e6b8
|
1115 1116 1117 1118 1119 1120 |
{ 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++) { |
3c7b4e6b8
|
1121 |
struct kmemleak_object *object; |
8e019366b
|
1122 1123 |
unsigned long flags; unsigned long pointer; |
3c7b4e6b8
|
1124 |
|
4b8a96744
|
1125 1126 |
if (allow_resched) cond_resched(); |
3c7b4e6b8
|
1127 1128 |
if (scan_should_stop()) break; |
8e019366b
|
1129 1130 1131 1132 1133 1134 |
/* don't scan uninitialized memory */ if (!kmemcheck_is_obj_initialized((unsigned long)ptr, BYTES_PER_POINTER)) continue; pointer = *ptr; |
3c7b4e6b8
|
1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 |
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++; |
0587da40b
|
1165 |
if (color_gray(object)) { |
3c7b4e6b8
|
1166 |
list_add_tail(&object->gray_list, &gray_list); |
0587da40b
|
1167 1168 1169 |
spin_unlock_irqrestore(&object->lock, flags); continue; } |
3c7b4e6b8
|
1170 |
spin_unlock_irqrestore(&object->lock, flags); |
0587da40b
|
1171 |
put_object(object); |
3c7b4e6b8
|
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 |
} } /* * 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; /* |
21ae2956c
|
1186 1187 |
* Once the object->lock is acquired, the corresponding memory block * cannot be freed (the same lock is acquired in delete_object). |
3c7b4e6b8
|
1188 1189 1190 1191 1192 1193 1194 |
*/ spin_lock_irqsave(&object->lock, flags); if (object->flags & OBJECT_NO_SCAN) goto out; if (!(object->flags & OBJECT_ALLOCATED)) /* already freed object */ goto out; |
af98603da
|
1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 |
if (hlist_empty(&object->area_list)) { void *start = (void *)object->pointer; void *end = (void *)(object->pointer + object->size); while (start < end && (object->flags & OBJECT_ALLOCATED) && !(object->flags & OBJECT_NO_SCAN)) { scan_block(start, min(start + MAX_SCAN_SIZE, end), object, 0); start += MAX_SCAN_SIZE; spin_unlock_irqrestore(&object->lock, flags); cond_resched(); spin_lock_irqsave(&object->lock, flags); } } else |
3c7b4e6b8
|
1210 |
hlist_for_each_entry(area, elem, &object->area_list, node) |
c017b4be3
|
1211 1212 1213 |
scan_block((void *)area->start, (void *)(area->start + area->size), object, 0); |
3c7b4e6b8
|
1214 1215 1216 1217 1218 |
out: spin_unlock_irqrestore(&object->lock, flags); } /* |
04609ccc4
|
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 |
* Scan the objects already referenced (gray objects). More objects will be * referenced and, if there are no memory leaks, all the objects are scanned. */ static void scan_gray_list(void) { struct kmemleak_object *object, *tmp; /* * 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 incremented. */ object = list_entry(gray_list.next, typeof(*object), gray_list); while (&object->gray_list != &gray_list) { cond_resched(); /* 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)); } /* |
3c7b4e6b8
|
1252 1253 1254 1255 1256 1257 1258 |
* 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; |
04609ccc4
|
1259 |
struct kmemleak_object *object; |
3c7b4e6b8
|
1260 |
int i; |
4698c1f2b
|
1261 |
int new_leaks = 0; |
3c7b4e6b8
|
1262 |
|
acf4968ec
|
1263 |
jiffies_last_scan = jiffies; |
3c7b4e6b8
|
1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 |
/* 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) { |
ae281064b
|
1274 1275 |
pr_debug("object->use_count = %d ", |
3c7b4e6b8
|
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 |
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 */ |
4b8a96744
|
1290 1291 |
scan_block(_sdata, _edata, NULL, 1); scan_block(__bss_start, __bss_stop, NULL, 1); |
3c7b4e6b8
|
1292 1293 1294 1295 1296 |
#ifdef CONFIG_SMP /* per-cpu sections scanning */ for_each_possible_cpu(i) scan_block(__per_cpu_start + per_cpu_offset(i), |
4b8a96744
|
1297 |
__per_cpu_end + per_cpu_offset(i), NULL, 1); |
3c7b4e6b8
|
1298 1299 1300 |
#endif /* |
029aeff5d
|
1301 |
* Struct page scanning for each node. |
3c7b4e6b8
|
1302 |
*/ |
029aeff5d
|
1303 |
lock_memory_hotplug(); |
3c7b4e6b8
|
1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 |
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; |
4b8a96744
|
1319 |
scan_block(page, page + 1, NULL, 1); |
3c7b4e6b8
|
1320 1321 |
} } |
029aeff5d
|
1322 |
unlock_memory_hotplug(); |
3c7b4e6b8
|
1323 1324 |
/* |
43ed5d6ee
|
1325 |
* Scanning the task stacks (may introduce false negatives). |
3c7b4e6b8
|
1326 1327 |
*/ if (kmemleak_stack_scan) { |
43ed5d6ee
|
1328 |
struct task_struct *p, *g; |
3c7b4e6b8
|
1329 |
read_lock(&tasklist_lock); |
43ed5d6ee
|
1330 1331 1332 1333 |
do_each_thread(g, p) { scan_block(task_stack_page(p), task_stack_page(p) + THREAD_SIZE, NULL, 0); } while_each_thread(g, p); |
3c7b4e6b8
|
1334 1335 1336 1337 1338 |
read_unlock(&tasklist_lock); } /* * Scan the objects already referenced from the sections scanned |
04609ccc4
|
1339 |
* above. |
3c7b4e6b8
|
1340 |
*/ |
04609ccc4
|
1341 |
scan_gray_list(); |
2587362ea
|
1342 1343 |
/* |
04609ccc4
|
1344 1345 |
* Check for new or unreferenced objects modified since the previous * scan and color them gray until the next scan. |
2587362ea
|
1346 1347 1348 1349 |
*/ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { spin_lock_irqsave(&object->lock, flags); |
04609ccc4
|
1350 1351 1352 1353 |
if (color_white(object) && (object->flags & OBJECT_ALLOCATED) && update_checksum(object) && get_object(object)) { /* color it gray temporarily */ object->count = object->min_count; |
2587362ea
|
1354 1355 1356 1357 1358 |
list_add_tail(&object->gray_list, &gray_list); } spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); |
04609ccc4
|
1359 1360 1361 1362 |
/* * Re-scan the gray list for modified unreferenced objects. */ scan_gray_list(); |
4698c1f2b
|
1363 1364 |
/* |
04609ccc4
|
1365 |
* If scanning was stopped do not report any new unreferenced objects. |
17bb9e0d9
|
1366 |
*/ |
04609ccc4
|
1367 |
if (scan_should_stop()) |
17bb9e0d9
|
1368 1369 1370 |
return; /* |
4698c1f2b
|
1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 |
* Scanning result reporting. */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { spin_lock_irqsave(&object->lock, flags); if (unreferenced_object(object) && !(object->flags & OBJECT_REPORTED)) { object->flags |= OBJECT_REPORTED; new_leaks++; } spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); if (new_leaks) pr_info("%d new suspected memory leaks (see " "/sys/kernel/debug/kmemleak) ", new_leaks); |
3c7b4e6b8
|
1389 1390 1391 1392 1393 1394 1395 1396 1397 |
} /* * 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; |
ae281064b
|
1398 1399 |
pr_info("Automatic memory scanning thread started "); |
bf2a76b31
|
1400 |
set_user_nice(current, 10); |
3c7b4e6b8
|
1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 |
/* * 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()) { |
3c7b4e6b8
|
1411 1412 1413 |
signed long timeout = jiffies_scan_wait; mutex_lock(&scan_mutex); |
3c7b4e6b8
|
1414 |
kmemleak_scan(); |
3c7b4e6b8
|
1415 |
mutex_unlock(&scan_mutex); |
4698c1f2b
|
1416 |
|
3c7b4e6b8
|
1417 1418 1419 1420 |
/* wait before the next scan */ while (timeout && !kthread_should_stop()) timeout = schedule_timeout_interruptible(timeout); } |
ae281064b
|
1421 1422 |
pr_info("Automatic memory scanning thread ended "); |
3c7b4e6b8
|
1423 1424 1425 1426 1427 1428 |
return 0; } /* * Start the automatic memory scanning thread. This function must be called |
4698c1f2b
|
1429 |
* with the scan_mutex held. |
3c7b4e6b8
|
1430 |
*/ |
7eb0d5e5b
|
1431 |
static void start_scan_thread(void) |
3c7b4e6b8
|
1432 1433 1434 1435 1436 |
{ if (scan_thread) return; scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak"); if (IS_ERR(scan_thread)) { |
ae281064b
|
1437 1438 |
pr_warning("Failed to create the scan thread "); |
3c7b4e6b8
|
1439 1440 1441 1442 1443 1444 |
scan_thread = NULL; } } /* * Stop the automatic memory scanning thread. This function must be called |
4698c1f2b
|
1445 |
* with the scan_mutex held. |
3c7b4e6b8
|
1446 |
*/ |
7eb0d5e5b
|
1447 |
static void stop_scan_thread(void) |
3c7b4e6b8
|
1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 |
{ 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; |
b87324d08
|
1464 1465 1466 1467 1468 |
int err; err = mutex_lock_interruptible(&scan_mutex); if (err < 0) return ERR_PTR(err); |
3c7b4e6b8
|
1469 |
|
3c7b4e6b8
|
1470 1471 1472 1473 1474 1475 1476 1477 1478 |
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: |
3c7b4e6b8
|
1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 |
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); |
3c7b4e6b8
|
1493 |
|
3c7b4e6b8
|
1494 |
list_for_each_continue_rcu(n, &object_list) { |
52c3ce4ec
|
1495 1496 1497 1498 |
struct kmemleak_object *obj = list_entry(n, struct kmemleak_object, object_list); if (get_object(obj)) { next_obj = obj; |
3c7b4e6b8
|
1499 |
break; |
52c3ce4ec
|
1500 |
} |
3c7b4e6b8
|
1501 |
} |
288c857d6
|
1502 |
|
3c7b4e6b8
|
1503 1504 1505 1506 1507 1508 1509 1510 1511 |
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) { |
b87324d08
|
1512 1513 1514 1515 1516 |
if (!IS_ERR(v)) { /* * kmemleak_seq_start may return ERR_PTR if the scan_mutex * waiting was interrupted, so only release it if !IS_ERR. */ |
f5886c7f9
|
1517 |
rcu_read_unlock(); |
b87324d08
|
1518 1519 1520 1521 |
mutex_unlock(&scan_mutex); if (v) put_object(v); } |
3c7b4e6b8
|
1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 |
} /* * 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); |
288c857d6
|
1533 |
if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) |
17bb9e0d9
|
1534 |
print_unreferenced(seq, object); |
3c7b4e6b8
|
1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 |
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) { |
b87324d08
|
1548 |
return seq_open(file, &kmemleak_seq_ops); |
3c7b4e6b8
|
1549 1550 1551 1552 |
} static int kmemleak_release(struct inode *inode, struct file *file) { |
b87324d08
|
1553 |
return seq_release(inode, file); |
3c7b4e6b8
|
1554 |
} |
189d84ed5
|
1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 |
static int dump_str_object_info(const char *str) { unsigned long flags; struct kmemleak_object *object; unsigned long addr; addr= simple_strtoul(str, NULL, 0); object = find_and_get_object(addr, 0); if (!object) { pr_info("Unknown object at 0x%08lx ", addr); return -EINVAL; } spin_lock_irqsave(&object->lock, flags); dump_object_info(object); spin_unlock_irqrestore(&object->lock, flags); put_object(object); return 0; } |
3c7b4e6b8
|
1576 |
/* |
30b371010
|
1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 |
* We use grey instead of black to ensure we can do future scans on the same * objects. If we did not do future scans these black objects could * potentially contain references to newly allocated objects in the future and * we'd end up with false positives. */ static void kmemleak_clear(void) { struct kmemleak_object *object; unsigned long flags; rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { spin_lock_irqsave(&object->lock, flags); if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) |
a1084c877
|
1592 |
__paint_it(object, KMEMLEAK_GREY); |
30b371010
|
1593 1594 1595 1596 1597 1598 |
spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); } /* |
3c7b4e6b8
|
1599 1600 1601 1602 1603 1604 1605 1606 1607 |
* 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) |
4698c1f2b
|
1608 |
* scan - trigger a memory scan |
30b371010
|
1609 1610 |
* clear - mark all current reported unreferenced kmemleak objects as * grey to ignore printing them |
189d84ed5
|
1611 |
* dump=... - dump information about the object found at the given address |
3c7b4e6b8
|
1612 1613 1614 1615 1616 1617 |
*/ 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; |
b87324d08
|
1618 |
int ret; |
3c7b4e6b8
|
1619 |
|
74341703e
|
1620 1621 |
if (!atomic_read(&kmemleak_enabled)) return -EBUSY; |
3c7b4e6b8
|
1622 1623 1624 1625 |
buf_size = min(size, (sizeof(buf) - 1)); if (strncpy_from_user(buf, user_buf, buf_size) < 0) return -EFAULT; buf[buf_size] = 0; |
b87324d08
|
1626 1627 1628 |
ret = mutex_lock_interruptible(&scan_mutex); if (ret < 0) return ret; |
3c7b4e6b8
|
1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 |
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; |
3c7b4e6b8
|
1641 |
|
b87324d08
|
1642 1643 1644 |
ret = strict_strtoul(buf + 5, 0, &secs); if (ret < 0) goto out; |
3c7b4e6b8
|
1645 1646 1647 1648 1649 |
stop_scan_thread(); if (secs) { jiffies_scan_wait = msecs_to_jiffies(secs * 1000); start_scan_thread(); } |
4698c1f2b
|
1650 1651 |
} else if (strncmp(buf, "scan", 4) == 0) kmemleak_scan(); |
30b371010
|
1652 1653 |
else if (strncmp(buf, "clear", 5) == 0) kmemleak_clear(); |
189d84ed5
|
1654 1655 |
else if (strncmp(buf, "dump=", 5) == 0) ret = dump_str_object_info(buf + 5); |
4698c1f2b
|
1656 |
else |
b87324d08
|
1657 1658 1659 1660 1661 1662 |
ret = -EINVAL; out: mutex_unlock(&scan_mutex); if (ret < 0) return ret; |
3c7b4e6b8
|
1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 |
/* 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, }; /* |
74341703e
|
1679 1680 1681 |
* 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). |
3c7b4e6b8
|
1682 |
*/ |
179a8100e
|
1683 |
static void kmemleak_do_cleanup(struct work_struct *work) |
3c7b4e6b8
|
1684 1685 |
{ struct kmemleak_object *object; |
74341703e
|
1686 |
bool cleanup = scan_thread == NULL; |
3c7b4e6b8
|
1687 |
|
4698c1f2b
|
1688 |
mutex_lock(&scan_mutex); |
3c7b4e6b8
|
1689 |
stop_scan_thread(); |
3c7b4e6b8
|
1690 |
|
74341703e
|
1691 1692 1693 1694 1695 1696 |
if (cleanup) { rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) delete_object_full(object->pointer); rcu_read_unlock(); } |
3c7b4e6b8
|
1697 |
mutex_unlock(&scan_mutex); |
3c7b4e6b8
|
1698 |
} |
179a8100e
|
1699 |
static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup); |
3c7b4e6b8
|
1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 |
/* * 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 */ |
3c7b4e6b8
|
1712 1713 1714 1715 |
atomic_set(&kmemleak_enabled, 0); /* check whether it is too early for a kernel thread */ if (atomic_read(&kmemleak_initialized)) |
179a8100e
|
1716 |
schedule_work(&cleanup_work); |
3c7b4e6b8
|
1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 |
pr_info("Kernel memory leak detector disabled "); } /* * 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(); |
ab0155a22
|
1731 1732 1733 |
else if (strcmp(str, "on") == 0) kmemleak_skip_disable = 1; else |
3c7b4e6b8
|
1734 1735 1736 1737 |
return -EINVAL; return 0; } early_param("kmemleak", kmemleak_boot_config); |
5f79020cb
|
1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 |
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: "); print_stack_trace(&trace, 2); } |
3c7b4e6b8
|
1749 |
/* |
2030117d2
|
1750 |
* Kmemleak initialization. |
3c7b4e6b8
|
1751 1752 1753 1754 1755 |
*/ void __init kmemleak_init(void) { int i; unsigned long flags; |
ab0155a22
|
1756 1757 |
#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF if (!kmemleak_skip_disable) { |
b370d29ea
|
1758 |
atomic_set(&kmemleak_early_log, 0); |
ab0155a22
|
1759 1760 1761 1762 |
kmemleak_disable(); return; } #endif |
3c7b4e6b8
|
1763 1764 1765 1766 1767 1768 |
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); |
b66930052
|
1769 1770 1771 1772 |
if (crt_early_log >= ARRAY_SIZE(early_log)) pr_warning("Early log buffer exceeded (%d), please increase " "DEBUG_KMEMLEAK_EARLY_LOG_SIZE ", crt_early_log); |
3c7b4e6b8
|
1773 1774 |
/* the kernel is still in UP mode, so disabling the IRQs is enough */ local_irq_save(flags); |
b66930052
|
1775 1776 1777 1778 1779 |
atomic_set(&kmemleak_early_log, 0); if (atomic_read(&kmemleak_error)) { local_irq_restore(flags); return; } else |
3c7b4e6b8
|
1780 |
atomic_set(&kmemleak_enabled, 1); |
3c7b4e6b8
|
1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 |
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: |
fd6789675
|
1793 |
early_alloc(log); |
3c7b4e6b8
|
1794 |
break; |
f528f0b8e
|
1795 1796 1797 |
case KMEMLEAK_ALLOC_PERCPU: early_alloc_percpu(log); break; |
3c7b4e6b8
|
1798 1799 1800 |
case KMEMLEAK_FREE: kmemleak_free(log->ptr); break; |
53238a60d
|
1801 1802 1803 |
case KMEMLEAK_FREE_PART: kmemleak_free_part(log->ptr, log->size); break; |
f528f0b8e
|
1804 1805 1806 |
case KMEMLEAK_FREE_PERCPU: kmemleak_free_percpu(log->ptr); break; |
3c7b4e6b8
|
1807 1808 1809 1810 1811 1812 1813 |
case KMEMLEAK_NOT_LEAK: kmemleak_not_leak(log->ptr); break; case KMEMLEAK_IGNORE: kmemleak_ignore(log->ptr); break; case KMEMLEAK_SCAN_AREA: |
c017b4be3
|
1814 |
kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL); |
3c7b4e6b8
|
1815 1816 1817 1818 1819 |
break; case KMEMLEAK_NO_SCAN: kmemleak_no_scan(log->ptr); break; default: |
5f79020cb
|
1820 1821 1822 1823 1824 1825 1826 1827 |
kmemleak_warn("Unknown early log operation: %d ", log->op_type); } if (atomic_read(&kmemleak_warning)) { print_log_trace(log); atomic_set(&kmemleak_warning, 0); |
3c7b4e6b8
|
1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 |
} } } /* * Late initialization function. */ static int __init kmemleak_late_init(void) { struct dentry *dentry; atomic_set(&kmemleak_initialized, 1); if (atomic_read(&kmemleak_error)) { /* |
25985edce
|
1843 |
* Some error occurred and kmemleak was disabled. There is a |
3c7b4e6b8
|
1844 1845 1846 1847 |
* 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. */ |
179a8100e
|
1848 |
schedule_work(&cleanup_work); |
3c7b4e6b8
|
1849 1850 1851 1852 1853 1854 |
return -ENOMEM; } dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL, &kmemleak_fops); if (!dentry) |
ae281064b
|
1855 1856 |
pr_warning("Failed to create the debugfs kmemleak file "); |
4698c1f2b
|
1857 |
mutex_lock(&scan_mutex); |
3c7b4e6b8
|
1858 |
start_scan_thread(); |
4698c1f2b
|
1859 |
mutex_unlock(&scan_mutex); |
3c7b4e6b8
|
1860 1861 1862 1863 1864 1865 1866 |
pr_info("Kernel memory leak detector initialized "); return 0; } late_initcall(kmemleak_late_init); |