DEBUG_BACKTRACE from MEM_guarded_alloc cannot resolve functions anymore in linux builds. #110971

New Issue

Bastien Montagne · 2023-08-09T17:51:14+02:00

Bastien Montagne commented

2023-08-09 17:51:14 +02:00

System Information
Operating system: Linux (gcc 13)
Graphics card: NA

Blender Version
Broken: current master
Worked: ?

Short description of error

After enabling DEBUG_BACKTRACE in mallocn_guarded_impl.c, the produced bactrace is essentially useless, since the call to backtrace_symbols in print_memhead_backtrace cannot resolve any of the return addresses in Blender code.

Exact steps for others to reproduce the error

Apply this trivial patch (enables the backtrace feature and generates a dummy memleak):

diff --git a/intern/guardedalloc/intern/mallocn_guarded_impl.c b/intern/guardedalloc/intern/mallocn_guarded_impl.c
index 35fe07e22a7..6d856b4d0e4 100644
--- a/intern/guardedalloc/intern/mallocn_guarded_impl.c
+++ b/intern/guardedalloc/intern/mallocn_guarded_impl.c
@@ -44,7 +44,7 @@
* memory block was allocated and print this trace for all
* unfreed blocks.
*/
-//#define DEBUG_BACKTRACE
+#define DEBUG_BACKTRACE
 
#ifdef DEBUG_BACKTRACE
#  define BACKTRACE_SIZE 100
diff --git a/source/blender/windowmanager/intern/wm_init_exit.cc b/source/blender/windowmanager/intern/wm_init_exit.cc
index 9b0641ceeb1..7d88e2b8f37 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.cc
+++ b/source/blender/windowmanager/intern/wm_init_exit.cc
@@ -220,6 +220,8 @@ void WM_init(bContext *C, int argc, const char **argv)
   BKE_sound_jack_sync_callback_set(sound_jack_sync_callback);
 }
 
+  MEM_mallocN(1024, __func__);
+
 GHOST_CreateSystemPaths();
 
 BKE_addon_pref_type_init();

Run Blender from the console, with --debug-memory option.

Result will be something like that in the console:

Error: Not freed memory blocks: 1, total unfreed memory 0.000977 MB
WM_init len: 1024 0x61c0000133e0
  /lib/x86_64-linux-gnu/libasan.so.8(+0x68e81) [0x7ff162c68e81]
  /home/guest/blender/build_main_debug/bin/blender() [0x136d4dfa]
  /home/guest/blender/build_main_debug/bin/blender() [0x136d5440]
  /home/guest/blender/build_main_debug/bin/blender() [0x136d583e]
  /home/guest/blender/build_main_debug/bin/blender() [0x137a242c]
  /home/guest/blender/build_main_debug/bin/blender() [0xef8a7b6]
  /lib/x86_64-linux-gnu/libc.so.6(+0x276ca) [0x7ff1500456ca]
  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85) [0x7ff150045785]
  /home/guest/blender/build_main_debug/bin/blender() [0xef89aa1]

Note that GDB does have access to the function names:

1 MEM_guarded_mallocN mallocn_guarded_impl.c 440 0x136d57ed 
2 WM_init             wm_init_exit.cc        223 0x137a242c 
3 main                creator.cc             537 0xef8a7b6

**System Information** Operating system: Linux (gcc 13) Graphics card: NA **Blender Version** Broken: current master Worked: ? **Short description of error** After enabling `DEBUG_BACKTRACE` in `mallocn_guarded_impl.c`, the produced bactrace is essentially useless, since the call to `backtrace_symbols` in `print_memhead_backtrace` cannot resolve any of the return addresses in Blender code. **Exact steps for others to reproduce the error** 1. Apply this trivial patch (enables the backtrace feature and generates a dummy memleak): ```Diff diff --git a/intern/guardedalloc/intern/mallocn_guarded_impl.c b/intern/guardedalloc/intern/mallocn_guarded_impl.c index 35fe07e22a7..6d856b4d0e4 100644 --- a/intern/guardedalloc/intern/mallocn_guarded_impl.c +++ b/intern/guardedalloc/intern/mallocn_guarded_impl.c @@ -44,7 +44,7 @@ * memory block was allocated and print this trace for all * unfreed blocks. */ -//#define DEBUG_BACKTRACE +#define DEBUG_BACKTRACE #ifdef DEBUG_BACKTRACE # define BACKTRACE_SIZE 100 diff --git a/source/blender/windowmanager/intern/wm_init_exit.cc b/source/blender/windowmanager/intern/wm_init_exit.cc index 9b0641ceeb1..7d88e2b8f37 100644 --- a/source/blender/windowmanager/intern/wm_init_exit.cc +++ b/source/blender/windowmanager/intern/wm_init_exit.cc @@ -220,6 +220,8 @@ void WM_init(bContext *C, int argc, const char **argv) BKE_sound_jack_sync_callback_set(sound_jack_sync_callback); } + MEM_mallocN(1024, __func__); + GHOST_CreateSystemPaths(); BKE_addon_pref_type_init(); ``` 2. Run Blender from the console, with `--debug-memory` option. Result will be something like that in the console: ``` Error: Not freed memory blocks: 1, total unfreed memory 0.000977 MB WM_init len: 1024 0x61c0000133e0 /lib/x86_64-linux-gnu/libasan.so.8(+0x68e81) [0x7ff162c68e81] /home/guest/blender/build_main_debug/bin/blender() [0x136d4dfa] /home/guest/blender/build_main_debug/bin/blender() [0x136d5440] /home/guest/blender/build_main_debug/bin/blender() [0x136d583e] /home/guest/blender/build_main_debug/bin/blender() [0x137a242c] /home/guest/blender/build_main_debug/bin/blender() [0xef8a7b6] /lib/x86_64-linux-gnu/libc.so.6(+0x276ca) [0x7ff1500456ca] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85) [0x7ff150045785] /home/guest/blender/build_main_debug/bin/blender() [0xef89aa1] ``` Note that GDB does have access to the function names: ``` 1 MEM_guarded_mallocN mallocn_guarded_impl.c 440 0x136d57ed 2 WM_init wm_init_exit.cc 223 0x137a242c 3 main creator.cc 537 0xef8a7b6 ```

Bastien Montagne added the

labels 2023-08-09 17:51:14 +02:00

Bastien Montagne commented

2023-08-09 18:12:53 +02:00

Note from an afternoon of investigations:

Could this be a GCC issue? I have the feeling I used this feature successfully a few months ago, however could not get it to work even in 4000 old commit on main.
Explored the web quite extensively, this post is the most interesting I found so far.
** Adding options like -rdynamic or -export-dynamic to the linker or compiler flags did not change anything.
** Explicitly enabling CMAKE_EXECUTABLE_ENABLE_EXPORTS did not help either.
** Explicitly building debug builds with -O0 flag did not solve it either.

Wondering whether we should not rather try to port guardedalloc to C++, and then try to use boost::stacktrace e.g. instead?

Note from an afternoon of investigations: * Could this be a GCC issue? I have the feeling I used this feature successfully a few months ago, however could not get it to work even in 4000 old commit on main. * Explored the web quite extensively, [this post](https://stackoverflow.com/questions/3899870/print-call-stack-in-c-or-c/69384663#69384663) is the most interesting I found so far. ** Adding options like `-rdynamic` or `-export-dynamic` to the linker or compiler flags did not change anything. ** Explicitly enabling [`CMAKE_EXECUTABLE_ENABLE_EXPORTS`](https://cmake.org/cmake/help/latest/variable/CMAKE_EXECUTABLE_ENABLE_EXPORTS.html#variable:CMAKE_EXECUTABLE_ENABLE_EXPORTS) did not help either. ** Explicitly building debug builds with `-O0` flag did not solve it either. ---------------- Wondering whether we should not rather try to port guardedalloc to C++, and then try to use boost::stacktrace e.g. instead?

Bastien Montagne added

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DEBUG_BACKTRACE from MEM_guarded_alloc cannot resolve functions anymore in linux builds. #110971

`DEBUG_BACKTRACE` from MEM_guarded_alloc cannot resolve functions anymore in linux builds. #110971