From: Christoph Hellwig <hch@lst.de> To: Marc Orr <marcorr@google.com> Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de, sagi@grimberg.me, jxgao@google.com, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] nvme: fix handling mapping failure Date: Tue, 19 Jan 2021 19:00:24 +0100 [thread overview] Message-ID: <20210119180024.GA28024@lst.de> (raw) In-Reply-To: <20210119175336.4016923-1-marcorr@google.com> On Tue, Jan 19, 2021 at 09:53:36AM -0800, Marc Orr wrote: > This patch ensures that when `nvme_map_data()` fails to map the > addresses in a scatter/gather list: > > * The addresses are not incorrectly unmapped. The underlying > scatter/gather code unmaps the addresses after detecting a failure. > Thus, unmapping them again in the driver is a bug. > * The DMA pool allocations are not deallocated when they were never > allocated. > > The bug that motivated this patch was the following sequence, which > occurred within the NVMe driver, with the kernel flag `swiotlb=force`. > > * NVMe driver calls dma_direct_map_sg() > * dma_direct_map_sg() fails part way through the scatter gather/list > * dma_direct_map_sg() calls dma_direct_unmap_sg() to unmap any entries > succeeded. > * NVMe driver calls dma_direct_unmap_sg(), redundantly, leading to a > double unmap, which is a bug. > > Before this patch, I observed intermittent application- and VM-level > failures when running a benchmark, fio, in an AMD SEV guest. This patch > resolves the failures. I think the right way to fix this is to just do a proper unwind insted of calling a catchall function. Can you try this patch? diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 25456d02eddb8c..47d7075053b6b2 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -842,7 +842,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, sg_init_table(iod->sg, blk_rq_nr_phys_segments(req)); iod->nents = blk_rq_map_sg(req->q, req, iod->sg); if (!iod->nents) - goto out; + goto out_free_sg; if (is_pci_p2pdma_page(sg_page(iod->sg))) nr_mapped = pci_p2pdma_map_sg_attrs(dev->dev, iod->sg, @@ -851,16 +851,25 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN); if (!nr_mapped) - goto out; + goto out_free_sg; iod->use_sgl = nvme_pci_use_sgls(dev, req); if (iod->use_sgl) ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped); else ret = nvme_pci_setup_prps(dev, req, &cmnd->rw); -out: if (ret != BLK_STS_OK) - nvme_unmap_data(dev, req); + goto out_dma_unmap; + return BLK_STS_OK; + +out_dma_unmap: + if (is_pci_p2pdma_page(sg_page(iod->sg))) + pci_p2pdma_unmap_sg(dev->dev, iod->sg, iod->nents, + rq_dma_dir(req)); + else + dma_unmap_sg(dev->dev, iod->sg, iod->nents, rq_dma_dir(req)); +out_free_sg: + mempool_free(iod->sg, dev->iod_mempool); return ret; }
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de> To: Marc Orr <marcorr@google.com> Cc: sagi@grimberg.me, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, axboe@fb.com, stable@vger.kernel.org, kbusch@kernel.org, hch@lst.de, jxgao@google.com Subject: Re: [PATCH] nvme: fix handling mapping failure Date: Tue, 19 Jan 2021 19:00:24 +0100 [thread overview] Message-ID: <20210119180024.GA28024@lst.de> (raw) In-Reply-To: <20210119175336.4016923-1-marcorr@google.com> On Tue, Jan 19, 2021 at 09:53:36AM -0800, Marc Orr wrote: > This patch ensures that when `nvme_map_data()` fails to map the > addresses in a scatter/gather list: > > * The addresses are not incorrectly unmapped. The underlying > scatter/gather code unmaps the addresses after detecting a failure. > Thus, unmapping them again in the driver is a bug. > * The DMA pool allocations are not deallocated when they were never > allocated. > > The bug that motivated this patch was the following sequence, which > occurred within the NVMe driver, with the kernel flag `swiotlb=force`. > > * NVMe driver calls dma_direct_map_sg() > * dma_direct_map_sg() fails part way through the scatter gather/list > * dma_direct_map_sg() calls dma_direct_unmap_sg() to unmap any entries > succeeded. > * NVMe driver calls dma_direct_unmap_sg(), redundantly, leading to a > double unmap, which is a bug. > > Before this patch, I observed intermittent application- and VM-level > failures when running a benchmark, fio, in an AMD SEV guest. This patch > resolves the failures. I think the right way to fix this is to just do a proper unwind insted of calling a catchall function. Can you try this patch? diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 25456d02eddb8c..47d7075053b6b2 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -842,7 +842,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, sg_init_table(iod->sg, blk_rq_nr_phys_segments(req)); iod->nents = blk_rq_map_sg(req->q, req, iod->sg); if (!iod->nents) - goto out; + goto out_free_sg; if (is_pci_p2pdma_page(sg_page(iod->sg))) nr_mapped = pci_p2pdma_map_sg_attrs(dev->dev, iod->sg, @@ -851,16 +851,25 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN); if (!nr_mapped) - goto out; + goto out_free_sg; iod->use_sgl = nvme_pci_use_sgls(dev, req); if (iod->use_sgl) ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped); else ret = nvme_pci_setup_prps(dev, req, &cmnd->rw); -out: if (ret != BLK_STS_OK) - nvme_unmap_data(dev, req); + goto out_dma_unmap; + return BLK_STS_OK; + +out_dma_unmap: + if (is_pci_p2pdma_page(sg_page(iod->sg))) + pci_p2pdma_unmap_sg(dev->dev, iod->sg, iod->nents, + rq_dma_dir(req)); + else + dma_unmap_sg(dev->dev, iod->sg, iod->nents, rq_dma_dir(req)); +out_free_sg: + mempool_free(iod->sg, dev->iod_mempool); return ret; } _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme
next prev parent reply other threads:[~2021-01-19 20:14 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-19 17:53 [PATCH] nvme: fix handling mapping failure Marc Orr 2021-01-19 17:53 ` Marc Orr 2021-01-19 18:00 ` Christoph Hellwig [this message] 2021-01-19 18:00 ` Christoph Hellwig 2021-01-19 23:12 ` Marc Orr 2021-01-19 23:12 ` Marc Orr
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20210119180024.GA28024@lst.de \ --to=hch@lst.de \ --cc=axboe@fb.com \ --cc=jxgao@google.com \ --cc=kbusch@kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-nvme@lists.infradead.org \ --cc=marcorr@google.com \ --cc=sagi@grimberg.me \ --cc=stable@vger.kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.