Re: [PATCH 0/5] migration: Fix migration state reference counting

[Peter Xu]

On Fri, Jan 19, 2024 at 08:39:17PM -0300, Fabiano Rosas wrote:
> We currently have a bug when running migration code in bottom
> halves. The issue has already been reported in Gitlab[1] and it
> started happening very frequently on my machine for some reason.
> 
> The issue is that we're dropping the last reference to the
> MigrationState object while the cleanup bottom half is still running
> and it leads to an use after free. More details on the commit message.
> 
> This series fixes the issue and does a refactoring around the
> migration BH scheduling aiming to consolidate some code so that it is
> less error prone.
> 
> 1- https://gitlab.com/qemu-project/qemu/-/issues/1969
> 
> CI run: https://gitlab.com/farosas/qemu/-/pipelines/1144927625
> 
> Fabiano Rosas (5):
>   migration: Fix use-after-free of migration state object
>   migration: Take reference to migration state around
>     bg_migration_vm_start_bh
>   migration: Reference migration state around
>     loadvm_postcopy_handle_run_bh
>   migration: Add a wrapper to qemu_bh_schedule
>   migration: Centralize BH creation and dispatch
> 
>  migration/migration.c | 82 +++++++++++++++++++++++++------------------
>  migration/migration.h |  5 +--
>  migration/savevm.c    |  5 +--
>  3 files changed, 49 insertions(+), 43 deletions(-)

Looks all good now, queued.  I'll amend the "Resolve:" line in patch 1.

-- 
Peter Xu