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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-87d02d890ffsm71384816d6.54.2025.10.21.09.03.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Oct 2025 09:03:41 -0700 (PDT) Date: Tue, 21 Oct 2025 12:03:39 -0400 From: Gregory Price To: Wei Yang Cc: Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, David Hildenbrand Subject: Re: [RFC PATCH v2] page_alloc: allow migration of smaller hugepages during contig_alloc Message-ID: References: <20251020210816.1089910-1-gourry@gourry.net> <20251021012533.56rdl6v76plkw4nl@master> <20251021091443.5ggfmvl5jwyknjnv@master> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251021091443.5ggfmvl5jwyknjnv@master> On Tue, Oct 21, 2025 at 09:14:43AM +0000, Wei Yang wrote: > > The above code is expanded to: > > page = _compound_head(page); > order = compound_order(page); > folio = page; > test_bit(PG_head, &folio->flags.f); > return folio_large_order(folio); > > If we use > > order = folio_order(page_folio(page)) > > It is expanded to: > > folio = _compound_head(page); > folio_test_large(folio) > folio_test_head(folio) > test_bit(PG_head, &folio->flags.f) > return folio_large_order(folio); > > These two seems expanded to the same code. > folio_test_large drops into const_folio_flags which does a VM_BUG_ON_PGFLAGS, so not the same logic here. > Maybe we can use folio_order() here? >