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[213.95.11.211]) by mx.google.com with ESMTPS id c23si3902679wmb.66.2019.08.09.07.36.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Aug 2019 07:36:26 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) client-ip=213.95.11.211; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de Received: by verein.lst.de (Postfix, from userid 2407) id E722868BFE; Fri, 9 Aug 2019 16:36:23 +0200 (CEST) Date: Fri, 9 Aug 2019 16:36:23 +0200 From: Christoph Hellwig To: Thomas Hellstrom Cc: Christoph Hellwig , Linus Torvalds , Andrew Morton , Jerome Glisse , Jason Gunthorpe , Steven Price , Linux-MM , Linux List Kernel Mailing Subject: Re: cleanup the walk_page_range interface Message-ID: <20190809143623.GA10269@lst.de> References: <20190808154240.9384-1-hch@lst.de> <20190808215632.GA12773@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) 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: On Fri, Aug 09, 2019 at 12:21:24AM +0200, Thomas Hellstrom wrote: > On 8/8/19 11:56 PM, Christoph Hellwig wrote: >> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote: >>>> Note that both Thomas and Steven have series touching this area pending, >>>> and there are a couple consumer in flux too - the hmm tree already >>>> conflicts with this series, and I have potential dma changes on top of >>>> the consumers in Thomas and Steven's series, so we'll probably need a >>>> git tree similar to the hmm one to synchronize these updates. >>> I'd be willing to just merge this now, if that helps. The conversion >>> is mechanical, and my only slight worry would be that at least for my >>> original patch I didn't build-test the (few) non-x86 >>> architecture-specific cases. But I did end up looking at them fairly >>> closely (basically using some grep/sed scripts to see that the >>> conversions I did matched the same patterns). And your changes look >>> like obvious improvements too where any mistake would have been caught >>> by the compiler. >> I did cross compile the s390 and powerpc bits, but I do not have an >> openrisc compiler. >> >>> So I'm not all that worried from a functionality standpoint, and if >>> this will help the next merge window, I'll happily pull now. >> That would help with this series vs the others, but not with the other >> series vs each other. > > Although my series doesn't touch the pagewalk code, it rather borrowed some > concepts from it and used for the apply_to_page_range() interface. > > The reason being that the pagewalk code requires the mmap_sem to be held > (mainly for trans-huge pages and reading the vma->vm_flags if I understand > the code correctly). That is fine when you scan the vmas of a process, but > the helpers I wrote need to instead scan all vmas pointing into a struct > address_space, and taking the mmap_sem for each vma will create lock > inversion problems. True. So you'll just need to apply the same lessons there, and we should probably fine with this series going into 5.3-rc.