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Tue, 20 Jan 2026 11:45:01 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface MIME-Version: 1.0 X-ThreadId: AWSx1lsrOtaB Date: Tue, 20 Jan 2026 17:44:29 +0100 From: "Arnd Bergmann" To: "Lorenzo Stoakes" Cc: "Jason Gunthorpe" , "Andrew Morton" , "Jarkko Sakkinen" , "Dave Hansen" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , x86@kernel.org, "H. Peter Anvin" , "Greg Kroah-Hartman" , "Dan Williams" , "Vishal Verma" , "Dave Jiang" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "Dave Airlie" , "Simona Vetter" , "Jani Nikula" , "Joonas Lahtinen" , "Rodrigo Vivi" , "Tvrtko Ursulin" , =?UTF-8?Q?Christian_K=C3=B6nig?= , "Huang Rui" , "Matthew Auld" , "Matthew Brost" , "Alexander Viro" , "Christian Brauner" , "Jan Kara" , "Benjamin LaHaise" , "Gao Xiang" , "Chao Yu" , "Yue Hu" , "Jeffle Xu" , "Sandeep Dhavale" , "Hongbo Li" , "Chunhai Guo" , "Theodore Ts'o" , "Andreas Dilger" , "Muchun Song" , "Oscar Salvador" , "David Hildenbrand (Red Hat)" , "Konstantin Komarov" , "Mike Marshall" , "Martin Brandenburg" , "Tony Luck" , "Reinette Chatre" , "Dave Martin" , "James Morse" , "Babu Moger" , "Carlos Maiolino" , "Damien Le Moal" , "Naohiro Aota" , "Johannes Thumshirn" , "Matthew Wilcox" , "Liam R. Howlett" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , "Hugh Dickins" , "Baolin Wang" , "Zi Yan" , "Nico Pache" , "Ryan Roberts" , "Dev Jain" , "Barry Song" , "Lance Yang" , "Jann Horn" , "Pedro Falcato" , "David Howells" , "Paul Moore" , "James Morris" , "Serge E. Hallyn" , "Yury Norov" , "Rasmus Villemoes" , linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, ntfs3@lists.linux.dev, devel@lists.orangefs.org, linux-xfs@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Message-Id: <9ff58468-a72d-4984-95f4-d0a60554705d@app.fastmail.com> In-Reply-To: <44461883-a75c-466b-a278-97c4ab46b461@lucifer.local> References: <20260119231403.GS1134360@nvidia.com> <36abc616-471b-4c7b-82f5-db87f324d708@lucifer.local> <20260120133619.GZ1134360@nvidia.com> <488a0fd8-5d64-4907-873b-60cefee96979@lucifer.local> <1617ac60-6261-483d-aeb5-13aba5f477af@app.fastmail.com> <44461883-a75c-466b-a278-97c4ab46b461@lucifer.local> Subject: Re: [PATCH RESEND 09/12] mm: make vm_area_desc utilise vma_flags_t only Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A7CBDC0008 X-Stat-Signature: dgcs7bi3xk8xjetsnx3omhrkwn7eobby X-Rspam-User: X-HE-Tag: 1768927506-469579 X-HE-Meta: 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 LZPoveid o2DEqIAdIbfmOSFaCfukKzY7pQ5LC7KQGsKwv9poxheL3GyuUIRbqxHCcwrPzVcdOsKTFPFDFBDMuUOYZg0fU+nnthRhFauiaWooCAhRKjMxDIDM/v/+aEN9/0Y++NNK3Xl6pQKd95ahV49ErE88Q4VeJBWaA1Hj3N+ERED461/v+nO4HmoBdVh9L/DAibCVcbK8SKpxH5u5i3Hz2/M0ahl6yePQxWwWuO2bzfqg7ds6ZdrMwQoTGp5Yj5tO8mxUsPPQZqbvjpL7DEXV2yz85n6YqdABi0qaR6w8Kpkh3+32oxWO2NxTCaCkIrKgYQinh2+jcCB9nPFHHkeOuU9Net1MGAQ== 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, Jan 20, 2026, at 17:22, Lorenzo Stoakes wrote: > On Tue, Jan 20, 2026 at 05:00:28PM +0100, Arnd Bergmann wrote: >> On Tue, Jan 20, 2026, at 16:10, Lorenzo Stoakes wrote: >> > >> > It strikes me that the key optimisation here is the inlining, now if the issue >> > is that ye olde compiler might choose not to inline very small functions (seems >> > unlikely) we could always throw in an __always_inline? >> >> I can think of three specific things going wrong with structures passed >> by value: > > I mean now you seem to be talking about it _in general_ which, _in theory_, > kills the whole concept of bitmap VMA flags _altogether_ really, or at > least any workable version of them. No, what I'm saying is "understand what the pitfalls are", not "don't do it". I think that is what Jason was also getting at. Arnd