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Tue, 17 Feb 2026 13:22:37 -0800 (PST) MIME-Version: 1.0 References: <20260213123902.3466040-1-arnd@kernel.org> <20260213085842.0654f70a73ec05d88908ec25@linux-foundation.org> <20260213092336.c2b0f2d1be17f1e2e9856f11@linux-foundation.org> In-Reply-To: From: Axel Rasmussen Date: Tue, 17 Feb 2026 13:22:01 -0800 X-Gm-Features: AaiRm53jGHGlihc9EP71VWUyZmyeH6xw45cRbipAYaUZYoNsokuMw5tTjVunGt0 Message-ID: Subject: Re: [PATCH] mm/vmscan: avoid false-positive -Wuninitialized warning To: Yuanchu Xie Cc: Andrew Morton , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 9F3498000B X-Stat-Signature: fzw35kzgqt1ejtpbkdk5fpoe6u7qin53 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1771363359-919738 X-HE-Meta: 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 8Y53LGNc nRHgkHUPmXUBsbDTf0svIGl5P1JHWPEpG1ThlE4qoje6PRSn4T5zcwC5rqP6yFe8+j53n/0F+cmBtji8Q/0sT40yTReMzrkghQY2DQh7bYAzChkGhnNRv+yorWrgHoEZAuOEGOhhtkq3Tk4++Zl+lY7gprBx9yWoZdvlpUJXMs1D79NeuFf1BvRouZjW3G38ZeFdsSCeYebYJC5a+emYyVqj6YEHyDgVLqOkuA5sSskhN4+2xxoHyy6pd7ZB4xecDDUCcmZLTVshT9QLO6VhSTNQImtZNUApxEYbGQQSh7axVtffFTO/UG+/MgRp3Xf0cplhePIUao2gkr+FUkpcUk43v5A== 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, Feb 17, 2026 at 12:55=E2=80=AFPM Yuanchu Xie w= rote: > > Hi Andrew and Arnd, > > On Fri, Feb 13, 2026 at 11:23=E2=80=AFAM Andrew Morton > wrote: > > > > On Fri, 13 Feb 2026 18:07:04 +0100 "Arnd Bergmann" wrot= e: > > > > > On Fri, Feb 13, 2026, at 17:58, Andrew Morton wrote: > > > > On Fri, 13 Feb 2026 13:38:56 +0100 Arnd Bergmann = wrote: > > > > > > > >> From: Arnd Bergmann > > > >> > > > >> When the -fsanitize=3Dbounds sanitizer is enabled, > > > > > > > > Is this an option in current kernels? > > > > > > Yes, this is CONFIG_UBSAN_ARRAY_BOUNDS. The actual warning > > > only shows up in some configurations with that, so either there > > > is some other dependency, or an element of chance based on gcc > > > optimizations. > > > > OK, I'll put a cc:stable on this, as people will want to compile older > > kernels with gcc-16. > > > > Aiming for upstreaming into 7.1-rc1 unless it's more urgent than I > > think. > > > > > > Seems a large change just to squish a compiler warning. People mig= ht > > > > prefer a simple > > > > > > > > - struct ctrl_pos sp, pv; > > > > + struct ctrl_pos sp, pv =3D {}; > > > > > > Right, that would clearly also shut up the warning. > > > > > > To me this seems less intuitive without an extra comment, > > > since read_ctrl_pos() is meant to initialize the entire > > > struct, but please pick whichever you find most readable > > > here. > > > > 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 =3D {};` > 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, > Yuanchu