On Wed, Jul 13, 2022 at 02:13:14PM +0100, Richard W.M. Jones wrote:
On Wed, Jul 13, 2022 at 03:10:37PM +0200, Laszlo Ersek wrote:
On 07/13/22 13:27, Richard W.M. Jones wrote:
It's not 100% reproducible, but it seems to happen reasonably often. Unfortunately it only happens on ppc64le (so far). The error message lacks sufficient detail to tell what's going on.
nbdkit: backend.c:624: backend_pread: Assertion `backend_valid_range (c, offset, count)' failed. nbdkit: backend.c:624: backend_pread: Assertion `backend_valid_range (c, offset, count)' failed.
Full log attached.
"tests/disk" has size 105923072.
Considering all the count=... offset=... lines in the last section of the log, there isn't one line where backend_valid_range():
return count > 0 && offset <= c->exportsize && offset + count <= c->exportsize;
would return false.
I've printed a table, with offset, count, and offset+count colums, from the log entries, then sorted the table three times separately, each time by a different column. I got the following min and max elements:
offset count offset+count --------- --------- ----------- 0 105923072 105923072 (min by offset) 105906176 16896 105923072 (max by offset) 0 4096 4096 (min by count) 0 105923072 105923072 (max by count) 0 4096 4096 (min by end) 105906176 16896 105923072 (max by end)
All of these look valid... I think you'll have to look at the coredump with gdb.
Indeed - unfortunately the coredump is on a Fedora build system :-(
I'll reserve a POWER machine later (unless someone gets there first).
I can't reproduce this after a few hours. I'll leave it running overnight, but the bug seems peculiarly rare on this reserved system, versus Fedora Koji where I observed it quite frequently. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org