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h=Date:From:To:Cc:Subject:In-Reply-To:References; b=eGNs2RSLhL2M9yMOdSs2XidbN91Dw5xcUl+25yjc7oNiTyl1FxuKKCr0l0KnLFyL8 eqvcJlGuLtAJ2RIqSbSJTk+f9VaY5nUZj6UVutP/hCQJceL4Z29aJIIoAqUoE3h7HC E3UfrBJbrA0MK4b9A81cH+8VPc5auKzDxJEXGJ+0= Date: Wed, 16 Sep 2026 16:08:19 -0700 From: Andrew Morton To: Arnd Bergmann Cc: Johannes Weiner , Arnd Bergmann , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , Ridong Chen , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/vmscan: avoid false-positive -Wuninitialized warning, again Message-Id: <20260916160819.a93fba485ffafe5b0e63b5f0@linux-foundation.org> In-Reply-To: <20260916083456.4136132-1-arnd@kernel.org> References: <20260916083456.4136132-1-arnd@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (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: rspam10 X-Rspamd-Queue-Id: 5917520007 X-Stat-Signature: 9mgpda5uzuxx7s6ga9wf7kf6xxegddxw X-Rspam-User: X-HE-Tag: 1789600101-320234 X-HE-Meta: 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 GvcMSqf2 /DFmdo10OAcCe9iqAJGXsJIVXVzMvLvoXkW+46Tcz+OLiWkrKlBcCER6te/GuCoTwVw6j+CGqwz8GCw5faPU21uWhUKz+GNPSCWdy3lu06+MJVb5Qr3sTBHWkB3L4k4dGcaHzZtRbn7a8piN6ZnPnarOHyPvrseij0HCYD18FS9DaPJEp1BWsYz7GiVHK1WdxZYGmM5LzAvKClLDE4klPT9OQRpcCKXAvrql9NIYlueav2r1l5IW4+iG98HHFa0dmVnYeozYyC4cXvrcdKaUxSxci1g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 16 Sep 2026 10:34:46 +0200 Arnd Bergmann wrote: > From: Arnd Bergmann > > I previously worked around a false-postive gcc-16 warning in the > get_tier_idx() function, by adding a fake initializer. This happens with > the -fsanitize=bounds sanitizer when the compiler creates a specialized > variant of isolate_folios(): > > In function 'get_tier_idx', > inlined from 'isolate_folios.constprop' at mm/vmscan.c:4982:9: > mm/vmscan.c:4934:9: error: 'sp.refaulted' is used uninitialized [-Werror=uninitialized] > 4934 | read_ctrl_pos(lruvec, type, LRU_TIER_MIN, LRU_TIER_MIN, 2, &sp); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > mm/vmscan.c: In function 'isolate_folios.constprop': > mm/vmscan.c:4946:25: note: 'sp.refaulted' was declared here > 4946 | struct ctrl_pos sp, pv = {}; > | ^~ > > Adding another "= {}" would solve the problem as well, but to prevent > this from happening again after the next code refactoring, try instead to > prevent this by forbidding interprocedural optimizations on this function. > > Link: https://lore.kernel.org/all/20260213123902.3466040-1-arnd@kernel.org/ > Fixes: 3de705a43a46 ("mm/vmscan: avoid false-positive -Wuninitialized warning") I believe we want older kernel to compile properly with gcc-16, so I'm suggesting this be backported? Perhaps we should have done that with 3de705a43a46 also.