text: #!/usr/bin/env python
  #
  # memleak   Trace and display outstanding allocations to detect
  #           memory leaks in user-mode processes and the kernel.
  #
  # USAGE: memleak [-h] [-p PID] [-t] [-a] [-o OLDER] [-c COMMAND]
  #                [--combined-only] [-s SAMPLE_RATE] [-T TOP] [-z MIN_SIZE]
  #                [-Z MAX_SIZE] [-O OBJ]
  #                [interval] [count]
  #
  # Licensed under the Apache License, Version 2.0 (the "License")
  # Copyright (C) 2016 Sasha Goldshtein.
  
  from bcc import BPF
  from time import sleep
  from datetime import datetime
  import resource
  import argparse
  import subprocess
  import os
  import sys
  
  class Allocation(object):
      def __init__(self, stack, size):
          self.stack = stack
          self.count = 1
          self.size = size
  
      def update(self, size):
          self.count += 1
          self.size += size
  
  def run_command_get_output(command):
          p = subprocess.Popen(command.split(),
                  stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
          return iter(p.stdout.readline, b'')
  
  def run_command_get_pid(command):
          p = subprocess.Popen(command.split())
          return p.pid
  
  examples = """
  EXAMPLES:
  
  ./memleak -p $(pidof allocs)
          Trace allocations and display a summary of "leaked" (outstanding)
          allocations every 5 seconds
  ./memleak -p $(pidof allocs) -t
          Trace allocations and display each individual allocator function call
  ./memleak -ap $(pidof allocs) 10
          Trace allocations and display allocated addresses, sizes, and stacks
          every 10 seconds for outstanding allocations
  ./memleak -c "./allocs"
          Run the specified command and trace its allocations
  ./memleak
          Trace allocations in kernel mode and display a summary of outstanding
          allocations every 5 seconds
  ./memleak -o 60000
          Trace allocations in kernel mode and display a summary of outstanding
          allocations that are at least one minute (60 seconds) old
  ./memleak -s 5
          Trace roughly every 5th allocation, to reduce overhead
  """
  
  description = """
  Trace outstanding memory allocations that weren't freed.
  Supports both user-mode allocations made with libc functions and kernel-mode
  allocations made with kmalloc/kmem_cache_alloc/get_free_pages and corresponding
  memory release functions.
  """
  
  parser = argparse.ArgumentParser(description=description,
          formatter_class=argparse.RawDescriptionHelpFormatter,
          epilog=examples)
  parser.add_argument("-p", "--pid", type=int, default=-1,
          help="the PID to trace; if not specified, trace kernel allocs")
  parser.add_argument("-t", "--trace", action="store_true",
          help="print trace messages for each alloc/free call")
  parser.add_argument("interval", nargs="?", default=5, type=int,
          help="interval in seconds to print outstanding allocations")
  parser.add_argument("count", nargs="?", type=int,
          help="number of times to print the report before exiting")
  parser.add_argument("-a", "--show-allocs", default=False, action="store_true",
          help="show allocation addresses and sizes as well as call stacks")
  parser.add_argument("-o", "--older", default=500, type=int,
          help="prune allocations younger than this age in milliseconds")
  parser.add_argument("-c", "--command",
          help="execute and trace the specified command")
  parser.add_argument("--combined-only", default=False, action="store_true",
          help="show combined allocation statistics only")
  parser.add_argument("-s", "--sample-rate", default=1, type=int,
          help="sample every N-th allocation to decrease the overhead")
  parser.add_argument("-T", "--top", type=int, default=10,
          help="display only this many top allocating stacks (by size)")
  parser.add_argument("-z", "--min-size", type=int,
          help="capture only allocations larger than this size")
  parser.add_argument("-Z", "--max-size", type=int,
          help="capture only allocations smaller than this size")
  parser.add_argument("-O", "--obj", type=str, default="c",
          help="attach to allocator functions in the specified object")
  parser.add_argument("--ebpf", action="store_true",
          help=argparse.SUPPRESS)
  
  args = parser.parse_args()
  
  pid = args.pid
  command = args.command
  kernel_trace = (pid == -1 and command is None)
  trace_all = args.trace
  interval = args.interval
  min_age_ns = 1e6 * args.older
  sample_every_n = args.sample_rate
  num_prints = args.count
  top_stacks = args.top
  min_size = args.min_size
  max_size = args.max_size
  obj = args.obj
  
  if min_size is not None and max_size is not None and min_size > max_size:
          print("min_size (-z) can't be greater than max_size (-Z)")
          exit(1)
  
  if command is not None:
          print("Executing '%s' and tracing the resulting process." % command)
          pid = run_command_get_pid(command)
  
  bpf_source = """
  #include <uapi/linux/ptrace.h>
  
  struct alloc_info_t {
          u64 size;
          u64 timestamp_ns;
          int stack_id;
  };
  
  struct combined_alloc_info_t {
          u64 total_size;
          u64 number_of_allocs;
  };
  
  BPF_HASH(sizes, u64);
  BPF_TABLE("hash", u64, struct alloc_info_t, allocs, 1000000);
  BPF_HASH(memptrs, u64, u64);
  BPF_STACK_TRACE(stack_traces, 10240);
  BPF_TABLE("hash", u64, struct combined_alloc_info_t, combined_allocs, 10240);
  
  static inline void update_statistics_add(u64 stack_id, u64 sz) {
          struct combined_alloc_info_t *existing_cinfo;
          struct combined_alloc_info_t cinfo = {0};
  
          existing_cinfo = combined_allocs.lookup(&stack_id);
          if (existing_cinfo != 0)
                  cinfo = *existing_cinfo;
  
          cinfo.total_size += sz;
          cinfo.number_of_allocs += 1;
  
          combined_allocs.update(&stack_id, &cinfo);
  }
  
  static inline void update_statistics_del(u64 stack_id, u64 sz) {
          struct combined_alloc_info_t *existing_cinfo;
          struct combined_alloc_info_t cinfo = {0};
  
          existing_cinfo = combined_allocs.lookup(&stack_id);
          if (existing_cinfo != 0)
                  cinfo = *existing_cinfo;
  
          if (sz >= cinfo.total_size)
                  cinfo.total_size = 0;
          else
                  cinfo.total_size -= sz;
  
          if (cinfo.number_of_allocs > 0)
                  cinfo.number_of_allocs -= 1;
  
          combined_allocs.update(&stack_id, &cinfo);
  }
  
  static inline int gen_alloc_enter(struct pt_regs *ctx, size_t size) {
          SIZE_FILTER
          if (SAMPLE_EVERY_N > 1) {
                  u64 ts = bpf_ktime_get_ns();
                  if (ts % SAMPLE_EVERY_N != 0)
                          return 0;
          }
  
          u64 pid = bpf_get_current_pid_tgid();
          u64 size64 = size;
          sizes.update(&pid, &size64);
  
          if (SHOULD_PRINT)
                  bpf_trace_printk("alloc entered, size = %u\\n", size);
          return 0;
  }
  
  static inline int gen_alloc_exit2(struct pt_regs *ctx, u64 address) {
          u64 pid = bpf_get_current_pid_tgid();
          u64* size64 = sizes.lookup(&pid);
          struct alloc_info_t info = {0};
  
          if (size64 == 0)
                  return 0; // missed alloc entry
  
          info.size = *size64;
          sizes.delete(&pid);
  
          info.timestamp_ns = bpf_ktime_get_ns();
          info.stack_id = stack_traces.get_stackid(ctx, STACK_FLAGS);
          allocs.update(&address, &info);
          update_statistics_add(info.stack_id, info.size);
  
          if (SHOULD_PRINT) {
                  bpf_trace_printk("alloc exited, size = %lu, result = %lx\\n",
                                   info.size, address);
          }
          return 0;
  }
  
  static inline int gen_alloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit2(ctx, PT_REGS_RC(ctx));
  }
  
  static inline int gen_free_enter(struct pt_regs *ctx, void *address) {
          u64 addr = (u64)address;
          struct alloc_info_t *info = allocs.lookup(&addr);
          if (info == 0)
                  return 0;
  
          allocs.delete(&addr);
          update_statistics_del(info->stack_id, info->size);
  
          if (SHOULD_PRINT) {
                  bpf_trace_printk("free entered, address = %lx, size = %lu\\n",
                                   address, info->size);
          }
          return 0;
  }
  
  int malloc_enter(struct pt_regs *ctx, size_t size) {
          return gen_alloc_enter(ctx, size);
  }
  
  int malloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int free_enter(struct pt_regs *ctx, void *address) {
          return gen_free_enter(ctx, address);
  }
  
  int calloc_enter(struct pt_regs *ctx, size_t nmemb, size_t size) {
          return gen_alloc_enter(ctx, nmemb * size);
  }
  
  int calloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int realloc_enter(struct pt_regs *ctx, void *ptr, size_t size) {
          gen_free_enter(ctx, ptr);
          return gen_alloc_enter(ctx, size);
  }
  
  int realloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int posix_memalign_enter(struct pt_regs *ctx, void **memptr, size_t alignment,
                           size_t size) {
          u64 memptr64 = (u64)(size_t)memptr;
          u64 pid = bpf_get_current_pid_tgid();
  
          memptrs.update(&pid, &memptr64);
          return gen_alloc_enter(ctx, size);
  }
  
  int posix_memalign_exit(struct pt_regs *ctx) {
          u64 pid = bpf_get_current_pid_tgid();
          u64 *memptr64 = memptrs.lookup(&pid);
          void *addr;
  
          if (memptr64 == 0)
                  return 0;
  
          memptrs.delete(&pid);
  
          if (bpf_probe_read(&addr, sizeof(void*), (void*)(size_t)*memptr64))
                  return 0;
  
          u64 addr64 = (u64)(size_t)addr;
          return gen_alloc_exit2(ctx, addr64);
  }
  
  int aligned_alloc_enter(struct pt_regs *ctx, size_t alignment, size_t size) {
          return gen_alloc_enter(ctx, size);
  }
  
  int aligned_alloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int valloc_enter(struct pt_regs *ctx, size_t size) {
          return gen_alloc_enter(ctx, size);
  }
  
  int valloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int memalign_enter(struct pt_regs *ctx, size_t alignment, size_t size) {
          return gen_alloc_enter(ctx, size);
  }
  
  int memalign_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  
  int pvalloc_enter(struct pt_regs *ctx, size_t size) {
          return gen_alloc_enter(ctx, size);
  }
  
  int pvalloc_exit(struct pt_regs *ctx) {
          return gen_alloc_exit(ctx);
  }
  """
  
  bpf_source_kernel = """
  
  TRACEPOINT_PROBE(kmem, kmalloc) {
          gen_alloc_enter((struct pt_regs *)args, args->bytes_alloc);
          return gen_alloc_exit2((struct pt_regs *)args, (size_t)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, kmalloc_node) {
          gen_alloc_enter((struct pt_regs *)args, args->bytes_alloc);
          return gen_alloc_exit2((struct pt_regs *)args, (size_t)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, kfree) {
          return gen_free_enter((struct pt_regs *)args, (void *)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, kmem_cache_alloc) {
          gen_alloc_enter((struct pt_regs *)args, args->bytes_alloc);
          return gen_alloc_exit2((struct pt_regs *)args, (size_t)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, kmem_cache_alloc_node) {
          gen_alloc_enter((struct pt_regs *)args, args->bytes_alloc);
          return gen_alloc_exit2((struct pt_regs *)args, (size_t)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, kmem_cache_free) {
          return gen_free_enter((struct pt_regs *)args, (void *)args->ptr);
  }
  
  TRACEPOINT_PROBE(kmem, mm_page_alloc) {
          gen_alloc_enter((struct pt_regs *)args, PAGE_SIZE << args->order);
          return gen_alloc_exit2((struct pt_regs *)args, args->pfn);
  }
  
  TRACEPOINT_PROBE(kmem, mm_page_free) {
          return gen_free_enter((struct pt_regs *)args, (void *)args->pfn);
  }
  """
  
  if kernel_trace:
          bpf_source += bpf_source_kernel
  
  bpf_source = bpf_source.replace("SHOULD_PRINT", "1" if trace_all else "0")
  bpf_source = bpf_source.replace("SAMPLE_EVERY_N", str(sample_every_n))
  bpf_source = bpf_source.replace("PAGE_SIZE", str(resource.getpagesize()))
  
  size_filter = ""
  if min_size is not None and max_size is not None:
          size_filter = "if (size < %d || size > %d) return 0;" % \
                        (min_size, max_size)
  elif min_size is not None:
          size_filter = "if (size < %d) return 0;" % min_size
  elif max_size is not None:
          size_filter = "if (size > %d) return 0;" % max_size
  bpf_source = bpf_source.replace("SIZE_FILTER", size_filter)
  
  stack_flags = "BPF_F_REUSE_STACKID"
  if not kernel_trace:
          stack_flags += "|BPF_F_USER_STACK"
  bpf_source = bpf_source.replace("STACK_FLAGS", stack_flags)
  
  if args.ebpf:
      print(bpf_source)
      exit()
  
  bpf = BPF(text=bpf_source)
  
  if not kernel_trace:
          print("Attaching to pid %d, Ctrl+C to quit." % pid)
  
          def attach_probes(sym, fn_prefix=None, can_fail=False):
                  if fn_prefix is None:
                          fn_prefix = sym
  
                  try:
                          bpf.attach_uprobe(name=obj, sym=sym,
                                            fn_name=fn_prefix + "_enter",
                                            pid=pid)
                          bpf.attach_uretprobe(name=obj, sym=sym,
                                               fn_name=fn_prefix + "_exit",
                                               pid=pid)
                  except Exception:
                          if can_fail:
                                  return
                          else:
                                  raise
  
          attach_probes("malloc")
          attach_probes("calloc")
          attach_probes("realloc")
          attach_probes("posix_memalign")
          attach_probes("valloc")
          attach_probes("memalign")
          attach_probes("pvalloc")
          attach_probes("aligned_alloc", can_fail=True)  # added in C11
          bpf.attach_uprobe(name=obj, sym="free", fn_name="free_enter",
                                    pid=pid)
  
  else:
          print("Attaching to kernel allocators, Ctrl+C to quit.")
  
          # No probe attaching here. Allocations are counted by attaching to
          # tracepoints.
          #
          # Memory allocations in Linux kernel are not limited to malloc/free
          # equivalents. It's also common to allocate a memory page or multiple
          # pages. Page allocator have two interfaces, one working with page
          # frame numbers (PFN), while other working with page addresses. It's
          # possible to allocate pages with one kind of functions, and free them
          # with another. Code in kernel can easy convert PFNs to addresses and
          # back, but it's hard to do the same in eBPF kprobe without fragile
          # hacks.
          #
          # Fortunately, Linux exposes tracepoints for memory allocations, which
          # can be instrumented by eBPF programs. Tracepoint for page allocations
          # gives access to PFNs for both allocator interfaces. So there is no
          # need to guess which allocation corresponds to which free.
  
  def print_outstanding():
          print("[%s] Top %d stacks with outstanding allocations:" %
                (datetime.now().strftime("%H:%M:%S"), top_stacks))
          alloc_info = {}
          allocs = bpf["allocs"]
          stack_traces = bpf["stack_traces"]
          for address, info in sorted(allocs.items(), key=lambda a: a[1].size):
                  if BPF.monotonic_time() - min_age_ns < info.timestamp_ns:
                          continue
                  if info.stack_id < 0:
                          continue
                  if info.stack_id in alloc_info:
                          alloc_info[info.stack_id].update(info.size)
                  else:
                          stack = list(stack_traces.walk(info.stack_id))
                          combined = []
                          for addr in stack:
                                  combined.append(bpf.sym(addr, pid,
                                          show_module=True, show_offset=True))
                          alloc_info[info.stack_id] = Allocation(combined,
                                                                 info.size)
                  if args.show_allocs:
                          print("\taddr = %x size = %s" %
                                (address.value, info.size))
          to_show = sorted(alloc_info.values(),
                           key=lambda a: a.size)[-top_stacks:]
          for alloc in to_show:
                  print("\t%d bytes in %d allocations from stack\n\t\t%s" %
                        (alloc.size, alloc.count, b"\n\t\t".join(alloc.stack)))
  
  def print_outstanding_combined():
          stack_traces = bpf["stack_traces"]
          stacks = sorted(bpf["combined_allocs"].items(),
                          key=lambda a: -a[1].total_size)
          cnt = 1
          entries = []
          for stack_id, info in stacks:
                  try:
                          trace = []
                          for addr in stack_traces.walk(stack_id.value):
                                  sym = bpf.sym(addr, pid,
                                                        show_module=True,
                                                        show_offset=True)
                                  trace.append(sym)
                          trace = "\n\t\t".join(trace)
                  except KeyError:
                          trace = "stack information lost"
  
                  entry = ("\t%d bytes in %d allocations from stack\n\t\t%s" %
                           (info.total_size, info.number_of_allocs, trace))
                  entries.append(entry)
  
                  cnt += 1
                  if cnt > top_stacks:
                          break
  
          print("[%s] Top %d stacks with outstanding allocations:" %
                (datetime.now().strftime("%H:%M:%S"), top_stacks))
  
          print('\n'.join(reversed(entries)))
  
  count_so_far = 0
  while True:
          if trace_all:
                  print(bpf.trace_fields())
          else:
                  try:
                          sleep(interval)
                  except KeyboardInterrupt:
                          exit()
                  if args.combined_only:
                          print_outstanding_combined()
                  else:
                          print_outstanding()
                  sys.stdout.flush()
                  count_so_far += 1
                  if num_prints is not None and count_so_far >= num_prints:
                          exit()
  