From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 572EB1B142B; Thu, 1 Aug 2024 15:22:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722525776; cv=none; b=fMHvfeMbWUqKZWPOSp9bAwWgQnxhopG42yG5na8mrpwQQ7MlJ7M0otQX0G+qpWKZo3cdlb+O9PYcR8A0cVuD7u2sI31C+b+VfSIvzUJ++Y1/BEwxoiZeLI1mEpqclxks6zjgl0SsVxZYYY/2YzBn7r+OnGfbU5fpPwRde4RlYTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722525776; c=relaxed/simple; bh=MCfSDdIjcHZQ9l663dFR3qY6umGQeR97WyGmOHY9GQc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t2ARvRB8W5dPC2GeYLbCa8gVZnyrkEF01ukx8XFYLlAPL5juwv6j87D7aQgOIUx9WCXRAthunC626oMxkhOJbhebB+8Rrea4vsBNY0mRVT6k3RXRBTKXv7RadICBRsVrWdvVhgukBDWNeqD6siLbiblRMBJwPjCOGn0rRcugbXQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Knkt0BM+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Knkt0BM+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E072FC32786; Thu, 1 Aug 2024 15:22:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722525775; bh=MCfSDdIjcHZQ9l663dFR3qY6umGQeR97WyGmOHY9GQc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Knkt0BM+MQksHfY/hnZ5m9c3nrY9foJmh8e9BoyHVve6RRLlCuddPDzrCGNCt/ftL mJF1PBOEm4zuxZ3M4vi/Iql7r+0kclcoSgV9S9lPeNHT6ZcMEgXBv/31FWDFXpO9Qb LgXolyyLaYGMKNhDuoXGyMRYwXifC+krPUjWBUsvb83wmz1H14Vz5okPqc/h8Ia081 +3ol8UNGML6OUyf9IM8ssrnducmo4Qp4OTOssdyBMF37pqAa9Wv7R9XPFa7QB9+a9l 4HzHa7PCR4h177R7pzQ5I1b5muNgo5WbJxJ4fv7jpaXCsxPzGrcizXKCx38obDNCND nUpMq3yjdLwOw== Date: Thu, 1 Aug 2024 08:22:53 -0700 From: Nathan Chancellor To: Christoph Hellwig Cc: kernel test robot , Baruch Siach , Marek Szyprowski , Catalin Marinas , Will Deacon , llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev, linux-s390@vger.kernel.org, Ramon Fried , Petr =?utf-8?B?VGVzYcWZw61r?= , Robin Murphy , linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Elad Nachman , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 2/3] dma-mapping: replace zone_dma_bits by zone_dma_limit Message-ID: <20240801152253.GA122261@thelio-3990X> References: <053fa4806a2c63efcde80caca473a8b670a2701c.1722249878.git.baruch@tkos.co.il> <202407300338.oaUo6jtB-lkp@intel.com> <20240730021208.GA8272@thelio-3990X> <20240730153450.GA30021@lst.de> <20240801012424.GA1640480@thelio-3990X> <20240801134454.GB2245@lst.de> Precedence: bulk X-Mailing-List: linux-s390@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: <20240801134454.GB2245@lst.de> On Thu, Aug 01, 2024 at 03:44:54PM +0200, Christoph Hellwig wrote: > On Wed, Jul 31, 2024 at 06:24:24PM -0700, Nathan Chancellor wrote: > > Unfortunately, I am not sure either... I do not see anything obviously, > > so perhaps it could just be avoided with the __diag() infrastructure? > > > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > > index 3dbc0b89d6fb..b58e7eb9c8f1 100644 > > --- a/kernel/dma/direct.c > > +++ b/kernel/dma/direct.c > > @@ -20,7 +20,12 @@ > > * it for entirely different regions. In that case the arch code needs to > > * override the variable below for dma-direct to work properly. > > */ > > +__diag_push(); > > +__diag_ignore(clang, 13, "-Wconstant-conversion", > > + "Clang incorrectly thinks the n == 64 case in DMA_BIT_MASK() can happen here," > > + "which would truncate with a 32-bit phys_addr_t"); > > phys_addr_t zone_dma_limit __ro_after_init = DMA_BIT_MASK(24); > > So.. The code above is clearly wrong, as DMA_BIT_MASK always returns a > u64, and phys_addr_t can be smaller than that. So at least in this case > the warning seems perfectly valid and the code has issues because it is > mixing different concepts. Sure, that seems like a reasonable way to look at things even if the warning itself is a false positive. > Where do you see warnings like this upstream? I don't see this upstream, this is from patch 2 of this series: https://lore.kernel.org/053fa4806a2c63efcde80caca473a8b670a2701c.1722249878.git.baruch@tkos.co.il/ Cheers, Nathan