Re: [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY

[Yajun Deng]

On 2023/10/12 17:19, Mike Rapoport wrote:
> On Thu, Oct 05, 2023 at 10:04:28PM +0800, Yajun Deng wrote:
> > > > > > > > That 'if' breaks the invariant that __free_pages_core is
> > > > > > > > always called for pages with initialized page count. Adding
> > > > > > > > it may lead to subtle bugs and random memory corruption so we
> > > > > > > > don't want to add it at the first place.
> > > > > > > As long as we have to special-case memory hotplug, we know that
> > > > > > > we are always coming via generic_online_page() in that case. We
> > > > > > > could either move some logic over there, or let
> > > > > > > __free_pages_core() know what it should do.
> > > > > > Looks like the patch rather special cases MEMINIT_EARLY, although
> > > > > > I didn't check throughfully other code paths.  Anyway, relying on
> > > > > > page_count() to be correct in different ways for different
> > > > > > callers of __free_pages_core() does not sound right to me.
> > > > > Absolutely agreed.
> > > > I already sent v5  a few days ago. Comments, please...
> > > Does it address all the feedback from this thread?
> > Except hotplug.
> Please reread carefully the last comments from me and from David above.

I replied in another thread about that 'if' statement. David just 
replied to me, let's discuss in another thread.