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Tue, 28 Sep 2021 13:05:07 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mVJLe-007GuE-T8; Tue, 28 Sep 2021 17:05:06 -0300 Date: Tue, 28 Sep 2021 17:05:06 -0300 From: Jason Gunthorpe To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , Christian =?utf-8?B?S8O2bmln?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni Subject: Re: [PATCH v3 19/20] PCI/P2PDMA: introduce pci_mmap_p2pmem() Message-ID: <20210928200506.GX3544071@ziepe.ca> References: <20210916234100.122368-1-logang@deltatee.com> <20210916234100.122368-20-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210916234100.122368-20-logang@deltatee.com> Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b="mXg4nC/0"; spf=pass (imf08.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.219.47 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3B11730000AA X-Stat-Signature: qqcj5wwu1a6jh791hkgkosfo359emrr8 X-HE-Tag: 1632859509-427459 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, Sep 16, 2021 at 05:40:59PM -0600, Logan Gunthorpe wrote: > +static void pci_p2pdma_unmap_mappings(void *data) > +{ > + struct pci_dev *pdev = data; > + struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); > + > + p2pdma->active = false; > + synchronize_rcu(); > + unmap_mapping_range(p2pdma->inode->i_mapping, 0, 0, 1); > + pci_p2pdma_free_mappings(p2pdma->inode->i_mapping); > +} If this is going to rely on unmap_mapping_range then GUP should also reject this memory for FOLL_LONGTERM.. What along this control flow: > + error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings, > + pdev); Waits for all the page refcounts to go to zero? Jason