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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id f14sm2400142qkk.89.2020.11.20.10.30.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Nov 2020 10:30:30 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kgBAz-008ujM-Ig; Fri, 20 Nov 2020 14:30:29 -0400 Date: Fri, 20 Nov 2020 14:30:29 -0400 From: Jason Gunthorpe To: Daniel Vetter Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, Daniel Vetter , Christoph Hellwig , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara Subject: Re: [PATCH v6 17/17] RFC: mm: add mmu_notifier argument to follow_pfn Message-ID: <20201120183029.GQ244516@ziepe.ca> References: <20201119144146.1045202-1-daniel.vetter@ffwll.ch> <20201119144146.1045202-18-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201119144146.1045202-18-daniel.vetter@ffwll.ch> 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 Thu, Nov 19, 2020 at 03:41:46PM +0100, Daniel Vetter wrote: > @@ -4805,21 +4824,15 @@ EXPORT_SYMBOL(follow_pte_pmd); > * Return: zero and the pfn at @pfn on success, -ve otherwise. > */ > int follow_pfn(struct vm_area_struct *vma, unsigned long address, > - unsigned long *pfn) > + unsigned long *pfn, struct mmu_notifier *subscription) > { > - int ret = -EINVAL; > - spinlock_t *ptl; > - pte_t *ptep; > + if (WARN_ON(!subscription->mm)) > + return -EINVAL; > > + if (WARN_ON(subscription->mm != vma->vm_mm)) > + return -EINVAL; These two things are redundant right? vma->vm_mm != NULL? BTW, why do we even have this for nommu? If the only caller is kvm, can you even compile kvm on nommu?? Jason