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[209.85.221.41]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7acad411d2sm422851666b.126.2024.07.28.13.32.04 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 28 Jul 2024 13:32:04 -0700 (PDT) Received: by mail-wr1-f41.google.com with SMTP id ffacd0b85a97d-36868fcb919so933471f8f.2 for ; Sun, 28 Jul 2024 13:32:04 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCUKMK0WWN1m40FyHbfJAiEugI9YggTcM8n+ROehuUC5QE4OZN7Ndb0p7GlLtPlu/5PZiuZ9+d80chg/HFpuzHioc1g= X-Received: by 2002:a05:6000:10cb:b0:367:8e53:7fd7 with SMTP id ffacd0b85a97d-36b5d0d10femr3393613f8f.28.1722198723859; Sun, 28 Jul 2024 13:32:03 -0700 (PDT) MIME-Version: 1.0 References: <402c3c617c29465c898b1af55e3c6095@AcuMS.aculab.com> <5cd3e11780df40b0b771da5548966ebd@AcuMS.aculab.com> In-Reply-To: From: Linus Torvalds Date: Sun, 28 Jul 2024 13:31:47 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/8] minmax: Put all the clamp() definitions together To: David Laight Cc: "linux-kernel@vger.kernel.org" , Jens Axboe , "Matthew Wilcox (Oracle)" , Christoph Hellwig , Andrew Morton , Andy Shevchenko , Dan Carpenter , Arnd Bergmann , "Jason@zx2c4.com" , "pedro.falcato@gmail.com" , Mateusz Guzik , "linux-mm@kvack.org" , Lorenzo Stoakes Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 45ue8woncq5djw3zqx6ab5ksw1ectzhd X-Rspam-User: X-Rspamd-Queue-Id: 03C811C0002 X-Rspamd-Server: rspam02 X-HE-Tag: 1722198726-384214 X-HE-Meta: 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 aex6pdyT cSpkoUT+mGK64c8EbhLYvLxPE78K5Y8cIme/KPb9Bx9L7zCj2r85uQjz1EHahqBg6u/f0KDbdByTmpkxg+lumqVk00E/kBdg6ZxqRc5pbWmfsSsn2XyXAtu069Ugsq7cV2Uztg7CnTub6MUuVc53tcXU/yKILnBU+sCQTXdDd2aQVkxUJUgEKsrzvEKAF75cESsbs/qNqJWTjaTeEZx/X35whHqDVVlAAXHnrJ4tcKDAsBPWwLQmxo8eGGguM6pRxpGgSYlezuMAUtY+Is0VyQcDR3Qk7qxWovyt3CGOHwV4hXDp00KH9k6EPB+q11A8jzVi9Yjb7xar8nAVH7G8sNceW2cQJ3vTYMPkgnpJVJeA95N8rN5VtypSKNTFGFA1UWA6Ho4YpKVSKSGX1mNNLoDoP4t4gvjjWBiEPV2QPB/6pRzzTde08+bOUlhOv+D8d9X/9s2Wp1+JI+HSz45LKYDTAjwa7G0E9pTbby6S7Kl/NIcM= 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 Sun, 28 Jul 2024 at 13:23, David Laight wrote: > > MIN() (and probably your MIN_T()) ought to have a check for > being a constant in order to stop misuse. No, we have a number of "runtime constants" that are basically "constants" set up at boot-time for the architecture,as pointed out by the powerpc people in private: Ie, we have arch/powerpc/include/asm/page.h: #define HPAGE_SHIFT hpage_shift and then #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) and then #define pageblock_order MIN_T(unsigned int, HUGETLB_PAGE_ORDER, MAX_PAGE_ORDER) and we really *REALLY* don't want to force the complicated "min_t()" (or, worse yet, "min()") functions here just because there's actually a variable involved. That variable gets initialized early in hugetlbpage_init_defaultsize(), so it's *effectively* a constant, but not as far as the compiler is concerned. Linus