[Libguestfs] Rare nbdkit crash on RISC-V

[Richard W.M. Jones]

I should add that these tests are run with MALLOC_CHECK_=1
MALLOC_PERTURB_=<random> which is probably why malloc_check appears in
the stack trace.

I commented out MALLOC_CHECK_ and ran the test a few more times, and
it still crashed (again, it's rare).  The new stack trace is below.
I've omitted threads which were waiting on pthread_mutex_lock.

Thread 4 (Thread 0x3fd2b876b0 (LWP 77382)):
#0  0x0000003fd300f978 in poll () from /lib64/lp64d/libc.so.6
#1  0x0000002ad4c60e18 in poll (__timeout=-1, __nfds=2, __fds=<optimized out>) at /usr/include/bits/poll2.h:46
#2  check_sockets_and_quit_fd (socks=0x3fffe43d78) at sockets.c:466
#3  accept_incoming_connections (socks=0x3fffe43d78) at sockets.c:540
#4  0x0000002ad4c58c6e in start_serving () at main.c:975
#5  main (argc=<optimized out>, argv=<optimized out>) at main.c:736

Thread 3 (Thread 0x3fd1382e50 (LWP 77404)):
#0  0x0000003fd30a4426 in read () from /lib64/lp64d/libpthread.so.0
#1  0x0000002ad4c5a1d6 in read (__nbytes=28, __buf=0x3fd13824a8, __fd=8) at /usr/include/bits/unistd.h:46
#2  raw_recv (vbuf=<optimized out>, len=28) at connections.c:459
#3  0x0000002ad4c6293e in protocol_recv_request_send_reply.isra.0 () at protocol.c:636
#4  0x0000002ad4c5c600 in connection_worker (data=0x3fcc0017e0) at connections.c:127
#5  0x0000003fd309c606 in start_thread () from /lib64/lp64d/libpthread.so.0
#6  0x0000003fd3016546 in __thread_start () from /lib64/lp64d/libc.so.6

Thread 2 (Thread 0x3fd2b85e50 (LWP 77391)):
#0  0x0000003fd309d650 in __pthread_clockjoin_ex () from /lib64/lp64d/libpthread.so.0
#1  0x0000002ad4c5e9a8 in handle_single_connection (sockin=<optimized out>, sockout=<optimized out>) at connections.c:221
#2  0x0000002ad4c6248a in start_thread (datav=0x2af1f2a160) at sockets.c:354
#3  0x0000003fd309c606 in start_thread () from /lib64/lp64d/libpthread.so.0
#4  0x0000003fd3016546 in __thread_start () from /lib64/lp64d/libc.so.6

Thread 1 (Thread 0x3fd1b83e50 (LWP 77403)):
#0  0x0000003fd2fd4a7e in __malloc_fork_lock_parent () from /lib64/lp64d/libc.so.6
#1  0x0000003fd2ff47ec in fork () from /lib64/lp64d/libc.so.6
#2  0x0000003fd326a50e in call3 (wbuf=wbuf at entry=0x0, wbuflen=wbuflen at entry=0, rbuf=rbuf at entry=0x3fd1b83260, rbuflen=rbuflen at entry=0x3fd1b83258, ebuf=ebuf at entry=0x3fd1b831f0, ebuflen=ebuflen at entry=0x3fd1b831e8, argv=argv at entry=0x3fd1b832e0) at call.c:214
#3  0x0000003fd326b4a8 in call_read (rbuf=rbuf at entry=0x3fd1b83260, rbuflen=rbuflen at entry=0x3fd1b83258, argv=argv at entry=0x3fd1b832e0) at call.c:521
#4  0x0000003fd326c678 in sh_extents (handle=<optimized out>, count=<optimized out>, offset=32768, flags=<optimized out>, extents=0x3fc8000bc0) at methods.c:1046
#5  0x0000002ad4c5e294 in plugin_extents (c=<optimized out>, count=<optimized out>, offset=<optimized out>, flags=<optimized out>, extents=0x3fc8000bc0, err=0x3fd1b83490) at plugins.c:761
#6  0x0000002ad4c5dedc in backend_extents (c=0x3fcc001040, count=<optimized out>, offset=32768, flags=<optimized out>, extents=0x3fc8000bc0, err=0x3fd1b83490) at backend.c:703
#7  0x0000002ad4c62ff2 in handle_request (extents=0x3fc8000bc0, buf=0x0, count=<optimized out>, offset=<optimized out>, flags=<optimized out>, cmd=<optimized out>) at protocol.c:285
#8  protocol_recv_request_send_reply.isra.0 () at protocol.c:716
--Type <RET> for more, q to quit, c to continue without paging--
#9  0x0000002ad4c5c600 in connection_worker (data=0x3fcc001650) at connections.c:127
#10 0x0000003fd309c606 in start_thread () from /lib64/lp64d/libpthread.so.0
#11 0x0000003fd3016546 in __thread_start () from /lib64/lp64d/libc.so.6

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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