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Date: Tue, 19 Aug 2025 13:39:15 +0300
From: Mike Rapoport <rppt@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: David Hildenbrand <david@redhat.com>, linux-mm@kvack.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Bill Wendling <morbo@google.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	Justin Stitt <justinstitt@google.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Miguel Ojeda <ojeda@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH 3/4] mm/mm_init: drop deferred_init_maxorder()
Message-ID: <aKRUUzq48xW5qPOp@kernel.org>
References: <20250818064615.505641-1-rppt@kernel.org>
 <20250818064615.505641-4-rppt@kernel.org>
 <408d7eaa-5aea-4490-9fd0-978c4eb94d32@redhat.com>
 <20250819092254.cddlg6npwl75fvbn@master>
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In-Reply-To: <20250819092254.cddlg6npwl75fvbn@master>

On Tue, Aug 19, 2025 at 09:22:54AM +0000, Wei Yang wrote:
> On Tue, Aug 19, 2025 at 09:54:22AM +0200, David Hildenbrand wrote:
> >> -static unsigned long __init
> >> -deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
> >> -			   struct zone *zone)
> >> -{
> >> -	unsigned long nr_pages = 0;
> >> -	unsigned long spfn, epfn;
> >> -	u64 i = 0;
> >> +		while (spfn < epfn) {
> >> +			unsigned long mo_pfn = ALIGN(spfn + 1, MAX_ORDER_NR_PAGES);
> >> +			unsigned long chunk_end = min(mo_pfn, epfn);
> >> -	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);
> >> +			nr_pages += deferred_init_pages(zone, spfn, chunk_end);
> >> +			deferred_free_pages(spfn, chunk_end - spfn);
> >
> >
> >I assume the expectation is that all PFNs in the start_pfn -> end_pfn range
> >will go to this zone, correct?
> 
> I think so.
> 
> defer_init only apply to the highest zone in one node.

Right, we defer initialization of last zone in every node and there is a
thread per node that does the initialization.

-- 
Sincerely yours,
Mike.