Re: [PATCH] mm: Fix memblock_free_late() when using deferred struct page

[Mike Rapoport <rppt@kernel.org>]

On Wed, Feb 11, 2026 at 10:23:06AM +1100, Benjamin Herrenschmidt wrote:
> On Tue, 2026-02-10 at 16:32 +0200, Mike Rapoport wrote:
> > Hi Ben,
> > 
> > On Tue, Feb 10, 2026 at 07:34:15PM +1100, Benjamin Herrenschmidt wrote:
> > > On Tue, 2026-02-10 at 17:17 +1100, Benjamin Herrenschmidt wrote:
> > > > 
> > > > So ... that was a backport to 6.12.68 and my original patch is
> > > > crashing
> > > > the same way ! (it was working last week interestingly enough,
> > > > something else got backported that gets in the way maybe ?).
> > > > 
> > > > I'm going to have to go back to digging :-(
> > > > 
> > > > I suspect the pages aren't reserved. I swear this was working :-)
> > > 
> > > So I rebuilt with a bit of extra debug prints, CONFIG_DEBUG_VM on, and
> > > memblock=debug ... it's not hitting the reserved check, but it's also
> > > not crashing the same way (still 6.12, I'll play with upstream again
> > > later):
> > > 
> > >   .../...
> > 
> > Do you mind sending the entire log?
> 
> I misplaced it, but give me a few days to dig see if I can find what's going on.

A log from any nano instance even without debug would be helpful. I'd like
to see what e820 table it has.

There always been some gap between e820 and memblock because historically
e820 does not consider some of the reserved memory as memory. 
If large enough parts of the boot services memory are E820_TYPE_RESERVED,
there might be no memory map for them at all.
 
> Cheers
> Ben.

-- 
Sincerely yours,
Mike.