rtorrent 0.9.8/0.13.8 crash on Rasberry PI4

[MetalKnight]

rtorrent version 0.9.8/0.13.8
raspberry PI4 kernel version: 6.1.21-v8+ aarch64 GNU/Linux

rtorrent runs on a Raspberry PI 4 with storage configured to ext4 HDD.
was running fine for ages, I've updated the PI4 to the latest update yesterday and now rtorrent crashes after downloading some data from a torrent.
restarting the process makes it crash the sameway after the file chcksum has been completed

Caught SIGBUS, dumping stack:
rtorrent() [0x1fdf0]
/lib/arm-linux-gnueabihf/libc.so.6(__default_rt_sa_restorer+0) [0xf7493910]
/usr/lib/arm-linux-gnueabihf/libtorrent.so.21(+0xd3af4) [0xf792aaf4]
/usr/lib/arm-linux-gnueabihf/libtorrent.so.21(_ZN7torrent9PollEPoll7performEv+0xe0) [0xf7894984]
/usr/lib/arm-linux-gnueabihf/libtorrent.so.21(_ZN7torrent9PollEPoll7do_pollExi+0x78) [0xf7894adc]
/usr/lib/arm-linux-gnueabihf/libtorrent.so.21(_ZN7torrent11thread_base10event_loopEPS0_+0x174) [0xf78d189c]
rtorrent() [0x1e660]
/lib/arm-linux-gnueabihf/libc.so.6(__libc_start_main+0x114) [0xf747b740]

Error: Success
Signal code '1': Invalid address alignment.
Fault address: 0x110946d
The fault address is not part of any chunk.

[MetalKnight]

this is the backtrace taken with gdb

(gdb) thread apply all backtrace

Thread 3 (Thread 0xf5dff200 (LWP 1536) "rtorrent scgi"):
#0  0xf7a7a1dc in epoll_wait (epfd=13, events=0x1f6750, maxevents=1024, timeout=600001) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
#1  0xf7dce898 in torrent::PollEPoll::poll(int) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#2  0xf7dceac8 in torrent::PollEPoll::do_poll(long long, int) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#3  0xf7e0b89c in torrent::thread_base::event_loop(torrent::thread_base*) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#4  0xf7af8310 in start_thread (arg=0xf5dff200) at pthread_create.c:477
#5  0xf7a79da8 in ?? () at ../sysdeps/unix/sysv/linux/arm/clone.S:73 from /lib/arm-linux-gnueabihf/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 2 (Thread 0xf6770200 (LWP 1535) "rtorrent disk"):
#0  0xf7a7a1dc in epoll_wait (epfd=10, events=0x1f01b8, maxevents=1024, timeout=10001) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
#1  0xf7dce898 in torrent::PollEPoll::poll(int) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#2  0xf7dceac8 in torrent::PollEPoll::do_poll(long long, int) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#3  0xf7e0b89c in torrent::thread_base::event_loop(torrent::thread_base*) () fro--Type <RET> for more, q to quit, c to continue without paging--
m /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#4  0xf7af8310 in start_thread (arg=0xf6770200) at pthread_create.c:477
#5  0xf7a79da8 in ?? () at ../sysdeps/unix/sysv/linux/arm/clone.S:73 from /lib/arm-linux-gnueabihf/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 1 (Thread 0xf6c2b040 (LWP 1531) "rtorrent main"):
#0  0xf7e64af4 in ?? () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#1  0xf7dce984 in torrent::PollEPoll::perform() () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#2  0xf7dceadc in torrent::PollEPoll::do_poll(long long, int) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#3  0xf7e0b89c in torrent::thread_base::event_loop(torrent::thread_base*) () from /usr/lib/arm-linux-gnueabihf/libtorrent.so.21
#4  0x0001e660 in ?? ()
#5  0xf79b5740 in __libc_start_main (main=0xfffef6e4, argc=-139534336, argv=0xf79b5740 <__libc_start_main+276>, init=<optimized out>, fini=0x170f98, rtld_fini=0xf7fcd510 <_dl_fini>, stack_end=0xfffef6e4) at libc-start.c:308
#6  0x0001f2c0 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

[MetalKnight]

seems similar to epics-base/pvDataCPP#84, at least in concept (unaligned access).
is there a way to have the debug symbols without recompiling from sources?

[MetalKnight]

I've also opened an issue to lib torrent
arvidn/libtorrent#7470

[kannibalox]

rTorrent uses a different libtorrent (https://github.com/rakshasa/libtorrent), but there's no need to have two identical tickets. If the raspi's package provider doesn't have the debug symbols, you'll probably have to compile from source.

[MetalKnight]

@kannibalox thanks for getting back.
so basically I need to clone this repo on my raspberry pi 4, have it run the same config file and provide backlog here?
Would that enough for you?

[MetalKnight]

@kannibalox I will open a new issue into the correct libtorrent and close this one if that's ok with you.

[MetalKnight]

@kannibalox I've opened rakshasa/libtorrent#244, we can move the discussion there

[MetalKnight]

I found a workaround:

launching rakshasa/libtorrent's configure with option --enable-aligned fixed the issue.
of course I had to manually build the rtorrent binary as well against the previous library
I also had to manually install: libssl-dev, libncurses5-dev, libncursesw5-dev, autoconf-archive, libcurl-dev.
I can revert to the old binary anytime if you still need me to help with debug the unaligned issue.