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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id s55sm1154161qtb.92.2020.05.19.17.19.11 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 May 2020 17:19:11 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jbCRz-0003QX-AW; Tue, 19 May 2020 21:19:11 -0300 Date: Tue, 19 May 2020 21:19:11 -0300 From: Jason Gunthorpe To: Alex Williamson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, cohuck@redhat.com, peterx@redhat.com Subject: Re: [PATCH 1/2] vfio: Introduce bus driver to IOMMU invalidation interface Message-ID: <20200520001911.GB31189@ziepe.ca> References: <158947414729.12590.4345248265094886807.stgit@gimli.home> <158947511830.12590.15083888449284990563.stgit@gimli.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <158947511830.12590.15083888449284990563.stgit@gimli.home> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, May 14, 2020 at 10:51:58AM -0600, Alex Williamson wrote: > @@ -1450,6 +1467,10 @@ static int vfio_pci_zap_and_vma_lock(struct vfio_pci_device *vdev, bool try) > > zap_vma_ptes(vma, vma->vm_start, > vma->vm_end - vma->vm_start); > + mutex_unlock(&vdev->vma_lock); > + up_read(&mm->mmap_sem); > + vfio_invalidate_pfnmap_vma(vdev->group, vma); > + goto again; The vma pointer can't leave the read side of the mmap_sem > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 4a4cb7cd86b2..62ba6bd8a486 100644 > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -91,6 +91,7 @@ struct vfio_dma { > bool lock_cap; /* capable(CAP_IPC_LOCK) */ > struct task_struct *task; > struct rb_root pfn_list; /* Ex-user pinned pfn list */ > + struct vm_area_struct *pfnmap_vma; This is also confusing, how does it prevent pfnmap_vma from becoming freed? Jason