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Tue, 13 Jan 2026 04:56:35 -0800 (PST) Date: Tue, 13 Jan 2026 15:56:30 +0300 From: Dan Carpenter To: Jan Kara Cc: oe-kbuild@lists.linux.dev, Roman Gushchin , lkp@intel.com, oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, Andrew Morton , Linux Memory Management List , Dev Jain Subject: Re: mm/filemap.c:3307 do_sync_mmap_readahead() warn: assigning (-12) to unsigned variable 'ra->order' Message-ID: References: <202601131311.g3lyUAks-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jan 13, 2026 at 01:24:20PM +0100, Jan Kara wrote: > On Tue 13-01-26 14:12:28, Dan Carpenter wrote: > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > head: b71e635feefc852405b14620a7fc58c4c80c0f73 > > commit: 9f1edf1aedac1b287355f63f768ba4275de72dca mm: readahead: make thp readahead conditional to mmap_miss logic > > config: x86_64-randconfig-161-20260113 (https://download.01.org/0day-ci/archive/20260113/202601131311.g3lyUAks-lkp@intel.com/config) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261) > > smatch version: v0.5.0-8985-g2614ff1a > > > > 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 > > | Reported-by: Dan Carpenter > > | Closes: https://lore.kernel.org/r/202601131311.g3lyUAks-lkp@intel.com/ > > > > smatch warnings: > > mm/filemap.c:3307 do_sync_mmap_readahead() warn: assigning (-12) to unsigned variable 'ra->order' > ... > > 9f1edf1aedac1b2 Roman Gushchin 2025-10-06 3306 ra->async_size = HPAGE_PMD_NR; > > 9f1edf1aedac1b2 Roman Gushchin 2025-10-06 @3307 ra->order = HPAGE_PMD_ORDER; > > > > HPAGE_PMD_SHIFT is zero in this config? > > ra->order is a u16. > > What's the config exactly? I suppose CONFIG_TRANSPARENT_HUGEPAGE is > disabled in this case, isn't it? In that case force_thp_readahead will > never be true and thus the branch with the assignment can never be reached > AFAICT... > Ah, yes. You are right. force_thp_readahead is false in this config. The truth is, I could easily disable these kinds of warnings in smatch because this is marked as an impossible path. if (is_impossible_path()) return... I've done that on a case by case basis in the past but maybe I should just do it globally. regards, dan carpenter