Re: Migration issues in qemu.git

[Avi Kivity <avi@redhat.com>]

  On 08/02/2010 12:06 PM, Avi Kivity wrote:
>  I'm hitting some migration issues merging qemu.git into qemu-kvm.git:
>
> 1. Crash in mig_cancel test:
>
> (gdb) bt
> #0  0x0000003a91c83dbb in memcpy () from /lib64/libc.so.6
> #1  0x000000000049c2ff in qemu_get_buffer (f=0x302d870, buf=<value 
> optimized out>, size1=4096) at /usr/include/bits/string3.h:52
> #2  0x0000000000409464 in ram_load (f=0x302d870, opaque=<value 
> optimized out>, version_id=4) at 
> /build/home/tlv/akivity/qemu-kvm/arch_init.c:407
> #3  0x000000000049cb4c in qemu_loadvm_state (f=0x302d870) at 
> savevm.c:1708
> #4  0x0000000000494169 in process_incoming_migration (f=<value 
> optimized out>) at migration.c:63
> #5  0x0000000000494517 in tcp_accept_incoming_migration (opaque=<value 
> optimized out>) at migration-tcp.c:163
> #6  0x000000000041b67e in main_loop_wait (nonblocking=<value optimized 
> out>) at /build/home/tlv/akivity/qemu-kvm/vl.c:1300
> #7  0x00000000004314e7 in kvm_main_loop () at 
> /build/home/tlv/akivity/qemu-kvm/qemu-kvm.c:1710
> #8  0x000000000041c67f in main_loop (argc=<value optimized out>, 
> argv=<value optimized out>, envp=<value optimized out>)
>     at /build/home/tlv/akivity/qemu-kvm/vl.c:1340
> #9  main (argc=<value optimized out>, argv=<value optimized out>, 
> envp=<value optimized out>) at /build/home/tlv/akivity/qemu-kvm/vl.c:3069
>
> This is on the incoming side so the test completes successfully, only 
> leaving a core dump to fill my disks.


This appears to be

> static inline void *host_from_stream_offset(QEMUFile *f,
>                                             ram_addr_t offset,
>                                             int flags)
> {
>     static RAMBlock *block = NULL;
>     char id[256];
>     uint8_t len;
>
>     if (flags & RAM_SAVE_FLAG_CONTINUE) {
>         if (!block) {
>             fprintf(stderr, "Ack, bad migration stream!\n");
>             return NULL;
>         }
>
>         return block->host + offset;
>     }

with block == NULL, if my gdb-fu got a static variable in an inlined 
function examined correctly.

I don't see any special reason for block to be NULL on a cancelled 
migration.  Though perhaps the incoming stream was terminated without us 
noticing, and we're migrating from some random buffer and confusing the 
code?

-- 
error compiling committee.c: too many arguments to function