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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id t6sm5001434qkd.60.2020.03.24.08.47.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 24 Mar 2020 08:47:09 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jGllk-0004Yc-Jf; Tue, 24 Mar 2020 12:47:08 -0300 Date: Tue, 24 Mar 2020 12:47:08 -0300 From: Jason Gunthorpe To: Christoph Hellwig Cc: Jerome Glisse , Ralph Campbell , Felix.Kuehling@amd.com, linux-mm@kvack.org, John Hubbard , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Philip Yang Subject: Re: [PATCH v2 hmm 7/9] mm/hmm: do not unconditionally set pfns when returning EBUSY Message-ID: <20200324154708.GA14119@ziepe.ca> References: <20200324011457.2817-1-jgg@ziepe.ca> <20200324011457.2817-8-jgg@ziepe.ca> <20200324073746.GF23447@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200324073746.GF23447@lst.de> User-Agent: Mutt/1.9.4 (2018-02-28) 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 Tue, Mar 24, 2020 at 08:37:46AM +0100, Christoph Hellwig wrote: > On Mon, Mar 23, 2020 at 10:14:55PM -0300, Jason Gunthorpe wrote: > > if (pte_none(pte)) { > > required_fault = hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0); > > if (required_fault) > > goto fault; > > + *pfn = range->values[HMM_PFN_NONE]; > > return 0; > > } > > > > @@ -274,8 +274,10 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, > > } > > > > required_fault = hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0); > > - if (!required_fault) > > + if (!required_fault) { > > + *pfn = range->values[HMM_PFN_NONE]; > > return 0; > > + } > > Maybe throw in a goto hole to consolidaste the set PFN and return > 0 cases? Then we have goto fault and goto none both ending in returns. I generally prefer the goto labels to have a single return The pte_unmap() before faulting makes this routine twisty and I haven't thought of a good way to untwist it Thanks, Jason