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b=XrOBsbtw/XYB5npPaSynS4CV4AMBE2tY55tK5rZrPjTRu1Ksi+UU4XhlDi22CE3Lh 7tBaBeRWmxegG5MC/sLM8ADqsy9h6jyPyZft5mRFvka/pPpPov08ffOJV/IX2oU9m4 Fow9Q5ZBHE07MmhCD/rVrE8InQjUJnoTCzLLXRas= Date: Thu, 11 Dec 2025 12:04:48 -0800 From: Andrew Morton To: Yankai Xu <815559068@qq.com> Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/gfp: cast GFP_ZONE_TABLE entries to long to avoid shift overflow Message-Id: <20251211120448.817a352350813ae84cb600b3@linux-foundation.org> In-Reply-To: References: 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-Queue-Id: 8D099C0016 X-Stat-Signature: zx3k7puc6updchfxktf43dekdaw1my56 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1765483490-31565 X-HE-Meta: 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 qn29IGDn stKq4 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 Thu, 11 Dec 2025 18:24:05 +0800 Yankai Xu <815559068@qq.com> wrote: > > When a new zone is added to enum zone_type in mmzone.h, the existing > GFP_ZONE_TABLE macro causes a compile-time shift overflow. Thanks. Please quote the compiler warning messages and describe how to reproduce this. Please include this info in the patch changelog and maintain it. > This happens > because enum zone_type is of type int. The shift is logically > valid because it has been checked by 16 * GFP_ZONES_SHIFT > BITS_PER_LONG previously. > > Fixed this by casting each value in GFP_ZONE_TABLE to type long. > > ... > > #define GFP_ZONE_TABLE ( \ > - (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ > + ((long)ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ It would be nice to find something nicer than this. Perhaps a type of something was poorly chosen.