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b=EoqRzVoPlrwY3Nev52tdMLwdD+AXArV8TgWwFCzDQcEecTZZe3pkuipRM6vRVG+tq DZVXwLgpxLSH1ZYQOXNDtpBhXx3bQsxyAjeIZ8BYjqyt965SwIjphmEpkj+/cpuTU1 ujUIKHDTQC+M087iAcdOgDqmlnCOmNI1DnePcCxmGUOa2P2VQnQyW1d1R+7nA9HwOT cCe/wx4N9CJW0NzVDG8ual/d+FHPGcOr9rgWdbAZbRGSoi4uNX6oVQT83T1WkNyNh+ E0cquw3bDTSnS62hyuCHmpUQ50cDHFy5dvHDvPZbExw5LzVCRK3Q5eBY+xG8jAlUdR mZ+IW64+Vrkdw== From: SeongJae Park To: kernel test robot Cc: SeongJae Park , Jiayuan Chen , oe-kbuild-all@lists.linux.dev, David Hildenbrand , Andrew Morton , Linux Memory Management List , mm-commits@vger.kernel.org, damon@lists.linux.dev Subject: Re: [akpm-mm:mm-new 222/223] include/linux/damon.h:869 damon_rand() warn: always true condition '(span <= (~0)) => (0-u32max <= u32max)' Date: Sat, 9 May 2026 09:22:01 -0700 Message-ID: <20260509162202.114645-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <202605092036.9mdDJbEZ-lkp@intel.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 335AC180004 X-Stat-Signature: 1scowwtxwmahx3mmo317jx7xchsx7pi8 X-Rspam-User: X-HE-Tag: 1778343745-317027 X-HE-Meta: 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 cGAgPUEf /ulPxo8anIJXsnOt2myhet/eAHfsqprmwuTpR7blhFC47PbNJS+Qq5bPcdDBGsWztVYn4jrlQxBX0oesH+raqNONglpPx8jnw0HSw+Kz6f+0vY2iXNlQ9uchyjeFtwrbTaBNzhowXGMafuKe2m7bX1y/31FNOXHtP3ehIzrAKTAQM6jHChwQA+dflTBRwYXaDnsYpOgFQbWpeAOCOvss/Fe1YWOu+zi8lFCNdmlx2gG8QVr8n0msw4CRf9Pr7z5wpT01oXkrPJvGVvFti2z9pPrxGK+BOK5h0TofHBvNRk/s1gKxLtgXxwE3zkNX1bS3+A5MZ5v2CVUWTZVPXYZFCm3+cJ8XpGo9qXaEv+o8d6SjpEoj3zTMJinZ4DXnEZObh13oOh/wHuaW7MhU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 09 May 2026 20:44:33 +0800 kernel test robot wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-new > head: 7505bb13a9bb1f214310915ccc06643119fdafc9 > commit: 8b7c38eb9621c71d288eca45c8dd4dc92357dc07 [222/223] mm/damon: replace damon_rand() with a per-ctx lockless PRNG > config: riscv-randconfig-r071-20260509 (https://download.01.org/0day-ci/archive/20260509/202605092036.9mdDJbEZ-lkp@intel.com/config) > compiler: riscv32-linux-gcc (GCC) 8.5.0 > smatch: v0.5.0-9065-ge9cc34fd > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-kbuild-all/202605092036.9mdDJbEZ-lkp@intel.com/ > > smatch warnings: > include/linux/damon.h:869 damon_rand() warn: always true condition '(span <= (~0)) => (0-u32max <= u32max)' > > vim +869 include/linux/damon.h > > 861 > 862 /* Get a random number in [@l, @r) using @ctx's lockless PRNG. */ > 863 static inline unsigned long damon_rand(struct damon_ctx *ctx, > 864 unsigned long l, unsigned long r) > 865 { > 866 unsigned long span = r - l; > 867 u64 rnd; > 868 > > 869 if (span <= U32_MAX) { > 870 rnd = prandom_u32_state(&ctx->rnd_state); > 871 return l + (unsigned long)((rnd * span) >> 32); > 872 } > 873 rnd = ((u64)prandom_u32_state(&ctx->rnd_state) << 32) | > 874 prandom_u32_state(&ctx->rnd_state); > 875 return l + mul_u64_u64_shr(rnd, span, 64); > 876 } > 877 The check is for 64bit systems. I think this warning is ok to be ignored. Please let me know if I'm missing something. Thanks, SJ [...]