Is there anything else I can provide to help getting this issue fixed?
The main issue is that snd_pcm_area_copy() gets called with overlapping source and destination buffers, which triggers this assertion before a memcpy:
http://git.alsa-project.org/?p=alsa-lib.git;a=blob;f=src/pcm/pcm.c;h=0d0d093...
This happens when the system is really loaded (CPU-wise).
Do you think the problem is likely to come from an incorrect API usage from the application? Knowing this would significantly narrow down the search, because the problem could also come from within alsa itself.
The callling code from the application is quite complex, see here:
https://github.com/savoirfairelinux/ring-daemon/blob/master/src/media/audio/...
In particular, the assertion is triggered by the call to snd_pcm_avail_update() at line 694 (see the stack trace below).
Thanks, Baptiste
On Wed, Jun 15, 2016 at 12:39:39AM +0200, Baptiste Jonglez wrote:
On Tue, Jun 14, 2016 at 11:02:21PM +0200, Baptiste Jonglez wrote:
Hi,
On Tue, Jun 07, 2016 at 07:29:35PM +0200, Baptiste Jonglez wrote:
When using Ring [1], an audio-video application, it sometimes crashes because of an assertion in libasound.so:
pcm.c:2758: snd_pcm_area_copy: Assertion `dst < src || dst >= src + bytes' failed.The complete upstream bug report is at [2]. The (not-so-useful) stack trace is the following:
<snip>
The next time it crashes, I will have debug symbols in dring. I can also recompile alsa-lib with debug symbols, what is the best way to do that?
As promised, here is a new stack trace with debug symbols:
<snip>
Sorry, this stack trace still had some arguments optimised out. Here is the stack trace without optimisation:
#0 0x00007f42a8696295 in raise () from /usr/lib/libc.so.6 #1 0x00007f42a86976da in abort () from /usr/lib/libc.so.6 #2 0x00007f42a868f297 in __assert_fail_base () from /usr/lib/libc.so.6 #3 0x00007f42a868f342 in __assert_fail () from /usr/lib/libc.so.6 #4 0x00007f42ad7463da in snd_pcm_area_copy (dst_area=0x7f4290ced250, dst_offset=144, src_area=0x7f4290ced260, src_offset=0, samples=0, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2758 #5 0x00007f42ad746918 in snd_pcm_areas_copy (dst_areas=0x7f427c000e90, dst_offset=72, src_areas=0x7f427c000e90, src_offset=0, channels=2, frames=1904, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2904 #6 0x00007f42ad79cb66 in softvol_convert_stereo_vol (svol=0x7f427c02f500, dst_areas=0x7f427c000e70, dst_offset=72, src_areas=0x7f427c000e70, src_offset=0, channels=2, frames=1904) at pcm_softvol.c:291 #7 0x00007f42ad79e081 in snd_pcm_softvol_read_areas (pcm=0x7f427c031080, areas=0x7f427c000e70, offset=72, size=1904, slave_areas=0x7f427c000e70, slave_offset=0, slave_sizep=0x7f4290ced408) at pcm_softvol.c:630 #8 0x00007f42ad75e367 in snd_pcm_plugin_avail_update (pcm=0x7f427c031080) at pcm_plugin.c:490 #9 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c031080) at pcm.c:2508 #10 0x00007f42ad75e214 in snd_pcm_plugin_avail_update (pcm=0x7f427c02fc70) at pcm_plugin.c:460 #11 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c02faa0) at pcm.c:2508 #12 0x00000000005486d4 in ring::AlsaLayer::capture (this=0x1978220) at alsalayer.cpp:694 #13 0x0000000000545de4 in ring::AlsaThread::run (this=0x19706f0) at alsalayer.cpp:137
Attached is a full stack trace with local variables. I can provide the core dump privately.
Also note that this happens when the application is under high CPU pressure (for instance other programs with higher priority are using all available CPU cores).
The calling code into the lib is here, when capturing from a device:
https://github.com/savoirfairelinux/ring-daemon/blob/master/src/media/audio/...
Baptiste
Is there anything in there that could explain the assertion failure? Perhaps a wrong API usage?
Thanks, Baptiste
Looking around, it seems other projects have run into the same issue:
https://aur.archlinux.org/packages/ultrastardx-git/?comments=all#comment-435458 https://aur.archlinux.org/packages/zoom/#comment-544696 http://ubuntuforums.org/showthread.php?t=2248373 https://github.com/js-platform/node-webrtc/issues/110 https://fedorahosted.org/fldigi/ticket/70The output of the alsa-info.sh script on my system is at [3]. What else can I provide to debug this issue further?
Thanks, Baptiste
[1] https://ring.cx [2] https://tuleap.ring.cx/plugins/tracker/?aid=502 [3] http://www.alsa-project.org/db/?f=0dd2ba1021b3d535f30f07c55dc18e2ef60db26d
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d7463da in snd_pcm_area_copy (dst_area=0x7f4290ced250, dst_offset=144, src_area=0x7f4290ced260, src_offset=0, samples=0, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2758 bytes = 15232 src = 0x7f427c0316b0 "" dst = 0x7f427c0318f0 "" width = 32 src_step = 32578 dst_step = -1865493936 __PRETTY_FUNCTION__ = "snd_pcm_area_copy" __FUNCTION__ = "snd_pcm_area_copy" #5 0x00007f42ad746918 in snd_pcm_areas_copy (dst_areas=0x7f427c000e90, dst_offset=72, src_areas=0x7f427c000e90, src_offset=0, channels=2, frames=1904, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2904 s = {addr = 0x7f427c0316b0, first = 0, step = 32} d = {addr = 0x7f427c0316b0, first = 0, step = 32} step = 64 src_addr = 0x7f427c0316b0 src_start = 0x7f427c000e70 channels1 = 0 chns = 2 dst_addr = 0x7f427c0316b0 dst_start = 0x7f427c000e70 width = 32 __PRETTY_FUNCTION__ = "snd_pcm_areas_copy" __FUNCTION__ = "snd_pcm_areas_copy" #6 0x00007f42ad79cb66 in softvol_convert_stereo_vol (svol=0x7f427c02f500, dst_areas=0x7f427c000e70, dst_offset=72, src_areas=0x7f427c000e70, src_offset=0, channels=2, frames=1904) at pcm_softvol.c:291 dst_area = 0x7f427c02f560 src_area = 0x7f427c031380 src_step = 32578 dst_step = 2909997239 vol_scale = 32578 vol = {2429473552, 1} vol_c = 2080568576 #7 0x00007f42ad79e081 in snd_pcm_softvol_read_areas (pcm=0x7f427c031080, areas=0x7f427c000e70, offset=72, size=1904, slave_areas=0x7f427c000e70, slave_offset=0, slave_sizep=0x7f4290ced408) at pcm_softvol.c:630 svol = 0x7f427c02f500 #8 0x00007f42ad75e367 in snd_pcm_plugin_avail_update (pcm=0x7f427c031080) at pcm_plugin.c:490 frames = 1904 cont = 1976 slave_frames = 2048 err = 0 slave_areas = 0x7f427c000e70 slave_offset = 0 result = 72 areas = 0x7f427c000e70 xfer = 144 hw_offset = 72 size = 1904 plugin = 0x7f427c02f500 slave = 0x7f427c030640 slave_size = 2472 #9 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c031080) at pcm.c:2508 No locals. #10 0x00007f42ad75e214 in snd_pcm_plugin_avail_update (pcm=0x7f427c02fc70) at pcm_plugin.c:460 plugin = 0x7f427c031310 slave = 0x7f427c031080 slave_size = 9255600 #11 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c02faa0) at pcm.c:2508 No locals. #12 0x00000000005486d4 in ring::AlsaLayer::capture (this=0x1978220) at alsalayer.cpp:694 mainBufferFormat = {sample_rate = 48000, nb_channels = 2, static DEFAULT_SAMPLE_RATE = 48000} toGetFrames = 32578 framesPerBufferAlsa = 5540553 #13 0x0000000000545de4 in ring::AlsaThread::run (this=0x19706f0) at alsalayer.cpp:137 No locals. d7463da in snd_pcm_area_copy (dst_area=0x7f4290ced250, dst_offset=144, src_area=0x7f4290ced260, src_offset=0, samples=0, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2758 bytes = 15232 src = 0x7f427c0316b0 "" dst = 0x7f427c0318f0 "" width = 32 src_step = 32578 dst_step = -1865493936 __PRETTY_FUNCTION__ = "snd_pcm_area_copy" __FUNCTION__ = "snd_pcm_area_copy" #5 0x00007f42ad746918 in snd_pcm_areas_copy (dst_areas=0x7f427c000e90, dst_offset=72, src_areas=0x7f427c000e90, src_offset=0, channels=2, frames=1904, format=SND_PCM_FORMAT_S32_LE) at pcm.c:2904 s = {addr = 0x7f427c0316b0, first = 0, step = 32} d = {addr = 0x7f427c0316b0, first = 0, step = 32} step = 64 src_addr = 0x7f427c0316b0 src_start = 0x7f427c000e70 channels1 = 0 chns = 2 dst_addr = 0x7f427c0316b0 dst_start = 0x7f427c000e70 width = 32 __PRETTY_FUNCTION__ = "snd_pcm_areas_copy" __FUNCTION__ = "snd_pcm_areas_copy" #6 0x00007f42ad79cb66 in softvol_convert_stereo_vol (svol=0x7f427c02f500, dst_areas=0x7f427c000e70, dst_offset=72, src_areas=0x7f427c000e70, src_offset=0, channels=2, frames=1904) at pcm_softvol.c:291 dst_area = 0x7f427c02f560 src_area = 0x7f427c031380 src_step = 32578 dst_step = 2909997239 vol_scale = 32578 vol = {2429473552, 1} vol_c = 2080568576 #7 0x00007f42ad79e081 in snd_pcm_softvol_read_areas (pcm=0x7f427c031080, areas=0x7f427c000e70, offset=72, size=1904, slave_areas=0x7f427c000e70, slave_offset=0, slave_sizep=0x7f4290ced408) at pcm_softvol.c:630 svol = 0x7f427c02f500 #8 0x00007f42ad75e367 in snd_pcm_plugin_avail_update (pcm=0x7f427c031080) at pcm_plugin.c:490 frames = 1904 cont = 1976 slave_frames = 2048 err = 0 slave_areas = 0x7f427c000e70 slave_offset = 0 result = 72 areas = 0x7f427c000e70 xfer = 144 hw_offset = 72 size = 1904 plugin = 0x7f427c02f500 slave = 0x7f427c030640 slave_size = 2472 #9 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c031080) at pcm.c:2508 No locals. #10 0x00007f42ad75e214 in snd_pcm_plugin_avail_update (pcm=0x7f427c02fc70) at pcm_plugin.c:460 plugin = 0x7f427c031310 slave = 0x7f427c031080 slave_size = 9255600 #11 0x00007f42ad745c3e in snd_pcm_avail_update (pcm=0x7f427c02faa0) at pcm.c:2508 No locals. #12 0x00000000005486d4 in ring::AlsaLayer::capture (this=0x1978220) at alsalayer.cpp:694 mainBufferFormat = {sample_rate = 48000, nb_channels = 2, static DEFAULT_SAMPLE_RATE = 48000} toGetFrames = 32578 framesPerBufferAlsa = 5540553 #13 0x0000000000545de4 in ring::AlsaThread::run (this=0x19706f0) at alsalayer.cpp:137 No locals.
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