Re: [PATCH 00/14] Fix memory region use-after-finalization

[Paolo Bonzini <pbonzini@redhat.com>]

On 9/17/25 12:32, Akihiko Odaki wrote:
> Based-on: <20250917-use-v3-0-72c2a6887c6c@rsg.ci.i.u-tokyo.ac.jp>
> ("[PATCH v3 0/7] Do not unparent in instance_finalize()")
> 
> This patch series was spun off from "[PATCH v2 00/15] Fix memory region
> leaks and use-after-finalization":
> https://lore.kernel.org/qemu-devel/20250915-use-v2-0-f4c7ff13bfe9@rsg.ci.i.u-tokyo.ac.jp/
> 
> When developing the next version of "[PATCH 00/16] memory: Stop
> piggybacking on memory region owners*", I faced multiple memory region
> leaks and use-after-finalization. This series extracts their fixes so
> that the number of Cc: won't explode.
> 
> Patch "qdev: Automatically delete memory subregions" and the succeeding
> patches are for refactoring, but patch "vfio-user: Do not delete the
> subregion" does fix use-after-finalization.
> 
> * https://lore.kernel.org/qemu-devel/20250901-mr-v1-0-dd7cb6b1480b@rsg.ci.i.u-tokyo.ac.jp/
> 
> Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>

This makes sense, but I think it is not bisectable, because of this in 
memory_region_del_subregion():

     assert(subregion->container == mr);
     subregion->container = NULL;

You would need to add a temporary

     if (subregion->container == NULL) {
         return;
     }

and undo it at the end of the series.  Do you agree?  With this change I 
can apply it.

Paolo