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b=w7Hi+7qArGNlgHXSRxaBfya7B2i7/oIuumZ/fcLv67qj7g4tbFZfOUR+D2UFlmcw0 wzywJ+r5MtK6tJjDFLxdZarWoa32yHo+ZmKlbM6s+rsNIr+FLHrPJD0FK57Ie/Kr7S 5jkStq8ANjWIPVfCLVbP9Yvt5MsY70yTZ/RwI+PQ= Date: Thu, 26 Mar 2026 19:15:10 -0700 From: Andrew Morton To: Axel Rasmussen Cc: Yuanchu Xie , Arnd Bergmann , Arnd Bergmann , Johannes Weiner , Wei Xu , "David Hildenbrand (Red Hat)" , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Baolin Wang , Kairui Song , Davidlohr Bueso , Koichiro Den , Jiayuan Chen , Bertrand Wlodarczyk , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/vmscan: avoid false-positive -Wuninitialized warning Message-Id: <20260326191510.31210c752099a708fe445d80@linux-foundation.org> In-Reply-To: References: <20260213123902.3466040-1-arnd@kernel.org> <20260213085842.0654f70a73ec05d88908ec25@linux-foundation.org> <20260213092336.c2b0f2d1be17f1e2e9856f11@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Stat-Signature: wfypdtmy77iz643hgt56x74isq884pxs X-Rspamd-Queue-Id: B0DB3140004 X-Rspam-User: X-HE-Tag: 1774577712-84760 X-HE-Meta: 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 jiq1+ScP ry7Xe0X/b/0hLNqW+Ge/5ILk7SozZOjE5CQZML0293PgZT1SPXMiybvoAeU4rzkrhhhylA/XiLPJr+Ak/bvFAVh4KXYG+HNk02Rb4L50qiT3uQCxLqVkLHuKd2u0yjvCYI4x136Qb4FNaaGevOgUlNFERz7e/QNmC8n4IhtN3jHAD2MBTDjM1fIK9BenyVkqtwg5ypFar3GNqmr6ONwvqzaSJA4E1VvNCq68h4e3o1Y17NKRzlMFs0Lj4uCtYDXCsseJVI1BtspFffkWnumY3+lPnFA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 17 Feb 2026 13:22:01 -0800 Axel Rasmussen wrote: > > > Let's see what the MGLRU maintainers have to say. > > > > I went over the various cases of read_ctrl_pos and couldn't find > > anything wrong (let me know if I'm mistaken), so this seems like a > > mild compiler bug we're trying to work around. Given it's one single > > version of gcc, I'm a fan of the simple `struct ctrl_pos sp, pv = {};` > > with a comment. > > Agreed, that simpler change with a comment seems better to me. > > I don't necessarily hate the refactor to split up the single / > aggregate cases, but if we were going to do that I'd probably have > aggregate_ctrl_pos call read_ctrl_pos to avoid duplicating the code, > and I'd want to consider marking read_ctrl_pos inline. > > But, it does seem like a large delta just to work around a false > positive warning. The simpler change would be easier to backport to > stable too for example. So on balance I'd prefer that. Thanks. Did anyone send a v2? If so, I misplaced it!