Re: [PATCH v7 1/2] memory: Update inline documentation

[Peter Xu]

On Tue, Jan 14, 2025 at 05:43:09PM +0900, Akihiko Odaki wrote:
> memory_region_finalize() is not a function to tell the owner is leaving, but
> the memory region itself is being destroyed.

It is when the lifecycle of the MR is the same as the owner.  That holds
true I suppose if without this patch, and that's why I don't prefer this
patch because it makes that part more complicated.

> It should not happen when a container is still referencing it. That is
> also why it has memory_region_ref(subregion) in
> memory_region_update_container_subregions() and assert(!mr->container) in
> memory_region_finalize().

Again, the line I added was sololy for what you said "automation" elsewhere
and only should work within MR-links within the same owner.  Otherwise
anyone referencing the MR would hold the owner ref then this finalize()
will never happen.

Now, if I could go back to your original purpose of this work, quotting
from your cover letter:

> I saw various sanitizer errors when running check-qtest-ppc64. While
> I could just turn off sanitizers, I decided to tackle them this time.
> 
> Unfortunately, GLib versions older than 2.81.0 do not free test data in
> some cases so some sanitizer errors remain. All sanitizer errors will be
> gone with this patch series combined with the following change for GLib:
> https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4120

Is check-qtest-ppc64 the only one that will trigger this issue?  Does it
mean that most of the devices will do proper removal of device-owned
subregions (hence, not prone to circular reference of owner refcount)
except some devices in ppc64?

-- 
Peter Xu