On 10/21/13 1:35 PM, Milan Kocian wrote:
hi,
sorry for writing it directly to you but I didn't find better recipient.
Does exist some mailing-list about lkvm?
I found the crash in virtio-net-rx thread (I can reproduce it every time
by 'aptitude update' in VM):
traps: virtio-net-rx[28933] general protection ip:7f00dda3d107 sp:7f00c58f4de8
error:0 in libc-2.17.so[7f00dd90f000+1a2000]
gdb backtrace:
(gdb) bt
#0 0x00007fb6a548e107 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x000000000041259c in memcpy_toiovecend (iov=0x7fb68d346ea0,
iov@entry=0x7fb68d345e90,
kdata=<optimized out>, kdata@entry=0x7fb68d346e90 "", offset=<optimized out>,
len=<optimized out>)
at util/iovec.c:70
#2 0x000000000040c66d in virtio_net_rx_thread (p=0x23688a0) at virtio/net.c:117
#3 0x00007fb6a5b2ee0e in start_thread () from
/lib/x86_64-linux-gnu/libpthread.so.0
#4 0x00007fb6a54489ed in clone () from /lib/x86_64-linux-gnu/libc.so.6
I tried to add some printf to diagnose it but it isn't clear to me:
virtio_net_rx_thread: before memcpy_toiovecend; copied: 0, len: 18890, iovsize:
4096, realiovsize: 4096
memcpy_toiovecend: offset: 0, len: 4096
memcpy_toiovecend: iov_len: 4096, len: 4096
virtio_net_rx_thread: before memcpy_toiovecend; copied: 4096, len: 18890,
iovsize: 4096, realiovsize: 4096
memcpy_toiovecend: offset: 4096, len: 4096
memcpy_toiovecend: iov_len: 4096, len: 4096
memcpy_toiovecend: iov_len: 0, len: 4096
memcpy_toiovecend: iov_len: 0, len: 4096
.
N x memcpy_toiovecend: iov_len: 0, len: 4096
.
memcpy_toiovecend: iov_len: 0, len: 4096
memcpy_toiovecend: iov_len: 0, len: 4096
memcpy_toiovecend: iov_len: 1519143547641528320, len: 4096
memcpy_toiovecend: iov_len: 193827583623176, len: 4096
./runlkvm.sh: line 2: 16090 Segmentation fault
IMHO problem come when received len size is bigger than maximum
of the dst iovec (realiovsize). Only iovec size is copied and in the next
run isn't place to copy the rest of len size.
So solution may be increase dst iovec size or send data in dst iovec
to user (but i don't know how, I am not virtio expert :-)).
I'm CC'ing Asias, Sasha and others.
Pekka
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