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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251021091443.5ggfmvl5jwyknjnv@master> X-Stat-Signature: 1ukmohjs7ek4dmy516yfcjnsh6843yho X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D113F40012 X-HE-Tag: 1761062622-287579 X-HE-Meta: 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 krQc4H0W yaglizo5vkpYknTMCGWHjHQHgfkKGJDjVxvkjygHBD5RmaGy/GlezLJOQdNOcbXbz3TrH1nYH4Ax2xeoPsTzPqtbn3/cwdjYpEWd1WK9KSCgl4a7pLiPOaZKKQroze44cz8gg/StzxRwRfSR4FpzG3n62Rx06s1u8BdG/E93YCUdIs2hCvx/gDvggGgBhkKhQoKHERSdp5xirmh3pGeSewihze6eiiW47+/dcl14zP/IpinnX/eehFCPXLC29BL8WKvR52cwAq+zVX97mrpFkzhTVsx/RojSbmHCi9apKdpst2AXKjY2NcIaASUPI5qL6S2GD3vxH3ipe0us7D7lJKM/Qg7jpthtzAQnIriXznO4f/xaS4OfRxqyruGfv8zk3tT/JVLH+/IfsZv5zaAixFTROpJpi9GBGZGxqxVJbY70yjem71pWoLbQ1pNUz7ZNv2H+E X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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? >