First, having a single qcow2 file open for read-write access by more
than one process in unsupported.
Second, this version of qemu/kvm is too old to be supported upstream,
it's a few years old already and there has been *lots* of changes since
that version.
** Changed in: qemu
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1179219
Title:
segfault in alloc_refcount_block
Status in QEMU:
Invalid
Bug description:
On CentOS-6.4.latest, I am trying to run several KVM VMs with
snapshots of a single qcow2 image. Randomly some VMs will crash
though. There's a downstream bug report at
http://bugs.centos.org/view.php?id=6441 and included in that is an
"abrt" crash report that contains the full stack trace as well as
disassembly etc. That report is at
http://bugs.centos.org/file_download.php?file_id=1486&type=bug
For convenience I will paste the segfaulting thread's stack trace
here:
:#0 0x00007f0d4d9fadd5 in alloc_refcount_block (bs=0x7f0d4fc38010,
offset=864752701576067072, length=<value optimized out>, addend=-1) at
/usr/src/debug/qemu-kvm-0.12.1.2/block/qcow2-refcount.c:335
: refcount_table_index = 402681856
: new_block = 131072
: table_size = <value optimized out>
: new_table = <value optimized out>
: old_table_offset = <value optimized out>
: old_free_cluster_index = <value optimized out>
: last_table_size = <value optimized out>
: refcount_block_clusters = <value optimized out>
: meta_offset = 2147483648
: table_offset = 2147614720
: s = 0x10000
: blocks_used = 1
: old_table_size = <value optimized out>
: ret = <value optimized out>
: new_blocks = 0x7f0d504babd0
: i = <value optimized out>
: table_clusters = <value optimized out>
: data = "\000\000\000\000\000\000\000\000e\240Y\003"
: blocks_clusters = <value optimized out>
: block = <value optimized out>
:#1 update_refcount (bs=0x7f0d4fc38010, offset=864752701576067072,
length=<value optimized out>, addend=-1) at
/usr/src/debug/qemu-kvm-0.12.1.2/block/qcow2-refcount.c:460
: block_index = <value optimized out>
: refcount = <value optimized out>
: cluster_index = 13195079064576
: table_index = 402681856
: s = 0x7f0d4fc35770
: start = 864752701576052736
: last = 864752701576118272
: cluster_offset = 864752701576052736
: refcount_block = 0x0
: old_table_index = <value optimized out>
: ret = <value optimized out>
:#2 0x00007f0d4d9fb710 in qcow2_free_clusters (bs=0x7f0d4fc38010,
offset=864752701576067072, size=65536) at
/usr/src/debug/qemu-kvm-0.12.1.2/block/qcow2-refcount.c:640
: ret = <value optimized out>
:#3 0x00007f0d4d9fd03e in qcow2_alloc_cluster_link_l2 (bs=0x7f0d4fc38010,
m=<value optimized out>) at
/usr/src/debug/qemu-kvm-0.12.1.2/block/qcow2-cluster.c:674
: s = <value optimized out>
: i = <value optimized out>
: j = <value optimized out>
: l2_index = 2032
: ret = <value optimized out>
: old_cluster = 0x7f0d4fd2b5e0
: start_sect = <value optimized out>
: l2_offset = 145358848
: l2_table = 0x0
: cluster_offset = <value optimized out>
: cow = <value optimized out>
:#4 0x00007f0d4d9f7d39 in qcow2_co_writev (bs=0x7f0d4fc38010,
sector_num=<value optimized out>, remaining_sectors=216, qiov=0x7f0d40051b40)
at /usr/src/debug/qemu-kvm-0.12.1.2/block/qcow2.c:632
: s = 0x7f0d4fc35770
: index_in_cluster = 120
: n_end = <value optimized out>
: ret = <value optimized out>
: cur_nr_sectors = 8
: cluster_offset = 274333696
: hd_qiov = {iov = 0x7f0d4001bcb0, niov = 1, nalloc = 26, size = 4096}
: bytes_done = <value optimized out>
: cluster_data = 0x0
: l2meta = {offset = 2817585152, cluster_offset = 274333696, n_start =
120, nb_available = 128, nb_clusters = 1, depends_on = 0x0, dependent_requests
= {entries = {tqh_first = 0x0, tqh_last = 0x7f0cf43dde78}}, next_in_flight =
{le_next = 0x0, le_prev = 0x7f0cefffee88}}
: __PRETTY_FUNCTION__ = "qcow2_co_writev"
:#5 0x00007f0d4d9e20b9 in bdrv_co_do_writev (bs=0x7f0d4fc38010,
sector_num=5503096, nb_sectors=216, qiov=0x7f0d40051b40, flags=<value optimized
out>) at /usr/src/debug/qemu-kvm-0.12.1.2/block.c:2081
: drv = 0x7f0d4de96f80
: req = {bs = 0x7f0d4fc38010, sector_num = 5503096, nb_sectors = 216,
is_write = true, list = {le_next = 0x0, le_prev = 0x7f0cefffef28}, co =
0x7f0d40002af0, wait_queue = {entries = {tqh_first = 0x0, tqh_last =
0x7f0cf43ddf40}}}
: ret = <value optimized out>
:#6 0x00007f0d4d9e2161 in bdrv_co_do_rw (opaque=0x7f0d4003ced0) at
/usr/src/debug/qemu-kvm-0.12.1.2/block.c:3497
: acb = 0x7f0d4003ced0
: bs = <value optimized out>
:#7 0x00007f0d4d9e7eeb in coroutine_trampoline (i0=<value optimized out>,
i1=<value optimized out>) at
/usr/src/debug/qemu-kvm-0.12.1.2/coroutine-ucontext.c:129
: self = 0x7f0d40002af0
: co = 0x7f0d40002af0
:#8 0x00007f0d4b31bb70 in ?? () from /lib64/libc-2.12.so
:No symbol table info available.
:#9 0x00007f0d44c0eed0 in ?? ()
:No symbol table info available.
:#10 0x0000000000000000 in ?? ()
It would appear, according to RPM at least that I am using 0.12.1.2 of
qemu/kvm on this machine.
I'm happy to provide any additional information test patches, etc.
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