Comment 2 for bug 1839428

This issue is very hard to reproduce.

It sometimes crashes, so I could mark few commits 'bad' while bisecting, but since it is not reliable, I'm not sure a commit is 'good' when there is no crash.

For now after hours of testing I could reduce Xujun Ma's range to qemu-v3.1.0..1d31f1872b:

commit 1d31f1872b337e4acac5bf6b3c2a45b66e43b494 (refs/bisect/bad)
Merge: 20b084c4b1 88c869198a
Author: Peter Maydell <email address hidden>
Date: Mon Mar 4 11:04:31 2019 +0000

    Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

    pci, pc, virtio: fixes, cleanups, tests

    Lots of work on tests: BiosTablesTest UEFI app,
    vhost-user testing for non-Linux hosts.
    Misc cleanups and fixes all over the place

    Signed-off-by: Michael S. Tsirkin <email address hidden>

    * remotes/mst/tags/for_upstream: (26 commits)
      pci: Sanity test minimum downstream LNKSTA
      hw/smbios: fix offset of type 3 sku field
      pci: Move NVIDIA vendor id to the rest of ids
      virtio-balloon: Safely handle BALLOON_PAGE_SIZE < host page size
      virtio-balloon: Use ram_block_discard_range() instead of raw madvise()
      virtio-balloon: Rework ballon_page() interface
      virtio-balloon: Corrections to address verification
      virtio-balloon: Remove unnecessary MADV_WILLNEED on deflate
      i386/kvm: ignore masked irqs when update msi routes
      contrib/vhost-user-blk: fix the compilation issue
      Revert "contrib/vhost-user-blk: fix the compilation issue"
      pc-dimm: use same mechanism for [get|set]_addr
      tests/data: introduce "uefi-boot-images" with the "bios-tables-test" ISOs
      tests/uefi-test-tools: add build scripts
      tests: introduce "uefi-test-tools" with the BiosTablesTest UEFI app
      roms: build the EfiRom utility from the roms/edk2 submodule
      roms: add the edk2 project as a git submodule
      vhost-user-test: create a temporary directory per TestServer
      vhost-user-test: small changes to init_hugepagefs
      vhost-user-test: create a main loop per TestServer
      ...