tests/acceptance/multiprocess.py test failure

[Cleber Rosa <crosa@redhat.com>]

Hi everyone,

The tests/acceptance/multiprocess.py:Multiprocess.test_multiprocess_x86_64
is currently failing (as of a9649a719a44894b81f38dc1c5c1888ee684acef).
Unfortunately CI was unable to catch this issue earlier, because tests
that require KVM are not yet running (but this should change soon).
The relevant part of the test logs is:

VM launch command: './qemu-system-x86_64 -display none -vga none
-chardev socket,id=mon,path=/var/tmp/avo_qemu_sock_5g22rvrp/qemu-427815-monitor.sock
-mon chardev=mon,mode=control -chardev
socket,id=console,path=/var/tmp/avo_qemu_sock_5g22rvrp/qemu-427815-console.sock,server=on,wait=off
-serial chardev:console -machine pc -accel kvm -cpu host -object
memory-backend-memfd,id=sysmem-file,size=2G --numa
node,memdev=sysmem-file -m 2048 -kernel
/home/cleber/avocado/data/cache/by_location/b4c64f15a75b083966d39d9246dd8db177736bb4/vmlinuz
-initrd /home/cleber/avocado/data/cache/by_location/b4c64f15a75b083966d39d9246dd8db177736bb4/initrd.img
-append printk.time=0 console=ttyS0 rdinit=/bin/bash -device
x-pci-proxy-dev,id=lsi1,fd=16'
>>> {'execute': 'qmp_capabilities'}

The test remains stuck here for as long as the test is allowed to run.
Because there's currently no timeout in the test, it can remain stuck
forever.  But, with a timeout, we end up getting:

Error launching VM
Command: './qemu-system-x86_64 -display none -vga none -chardev
socket,id=mon,path=/var/tmp/avo_qemu_sock_5g22rvrp/qemu-427815-monitor.sock
-mon chardev=mon,mode=control -chardev
socket,id=console,path=/var/tmp/avo_qemu_sock_5g22rvrp/qemu-427815-console.sock,server=on,wait=off
-serial chardev:console -machine pc -accel kvm -cpu host -object
memory-backend-memfd,id=sysmem-file,size=2G --numa
node,memdev=sysmem-file -m 2048 -kernel
/home/cleber/avocado/data/cache/by_location/b4c64f15a75b083966d39d9246dd8db177736bb4/vmlinuz
-initrd /home/cleber/avocado/data/cache/by_location/b4c64f15a75b083966d39d9246dd8db177736bb4/initrd.img
-append printk.time=0 console=ttyS0 rdinit=/bin/bash -device
x-pci-proxy-dev,id=lsi1,fd=16'
Output: "qemu-system-x86_64: ../../src/qemu/softmmu/physmem.c:2055:
qemu_ram_alloc_from_fd: Assertion `(ram_flags & ~(RAM_SHARED |
RAM_PMEM | RAM_NORESERVE)) == 0' failed.\n"

I've bisected it to:

---

d5015b80134047013eeec10000df5ce2014ee114 is the first bad commit
commit d5015b80134047013eeec10000df5ce2014ee114
Author: David Hildenbrand <david@redhat.com>
Date:   Mon May 10 13:43:17 2021 +0200

    softmmu/memory: Pass ram_flags to qemu_ram_alloc_from_fd()

    Let's pass in ram flags just like we do with qemu_ram_alloc_from_file(),
    to clean up and prepare for more flags.

    Simplify the documentation of passed ram flags: Looking at our
    documentation of RAM_SHARED and RAM_PMEM is sufficient, no need to be
    repetitive.

    Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
    Reviewed-by: Peter Xu <peterx@redhat.com>
    Acked-by: Eduardo Habkost <ehabkost@redhat.com> for memory backend
and machine core
    Signed-off-by: David Hildenbrand <david@redhat.com>
    Message-Id: <20210510114328.21835-5-david@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

 backends/hostmem-memfd.c | 7 ++++---
 hw/misc/ivshmem.c        | 5 ++---
 include/exec/memory.h    | 9 +++------
 include/exec/ram_addr.h  | 6 +-----
 softmmu/memory.c         | 7 +++----
 5 files changed, 13 insertions(+), 21 deletions(-)

---

To reproduce it:

1. configure --target-list=x86_64-softmmu
2. meson compile
3. make check-venv
4. ./tests/venv/bin/avocado --show=test run --job-timeout=20s
tests/acceptance/multiprocess.py:Multiprocess.test_multiprocess_x86_64

It'd be helpful to know if anyone else is experiencing the same failure.

Thanks,
- Cleber.