From: Marc Orr <marcorr@google.com> To: 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 Cc: Marc Orr <marcorr@google.com>, stable@vger.kernel.org Subject: [PATCH] nvme: fix handling mapping failure Date: Tue, 19 Jan 2021 09:53:36 -0800 [thread overview] Message-ID: <20210119175336.4016923-1-marcorr@google.com> (raw) 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. Tested-by: Marc Orr <marcorr@google.com> Cc: stable@vger.kernel.org Signed-off-by: Marc Orr <marcorr@google.com> --- drivers/nvme/host/pci.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 9b1fc8633cfe..8b504ed08321 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -543,11 +543,14 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req) WARN_ON_ONCE(!iod->nents); - 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)); + if (!dma_mapping_error(dev->dev, iod->first_dma)) { + 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)); + } if (iod->npages == 0) @@ -836,8 +839,11 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, else nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN); - if (!nr_mapped) + if (!nr_mapped) { + iod->first_dma = DMA_MAPPING_ERROR; + iod->npages = -1; goto out; + } iod->use_sgl = nvme_pci_use_sgls(dev, req); if (iod->use_sgl) -- 2.30.0.284.gd98b1dd5eaa7-goog
WARNING: multiple messages have this Message-ID (diff)
From: Marc Orr <marcorr@google.com> To: 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 Cc: Marc Orr <marcorr@google.com>, stable@vger.kernel.org Subject: [PATCH] nvme: fix handling mapping failure Date: Tue, 19 Jan 2021 09:53:36 -0800 [thread overview] Message-ID: <20210119175336.4016923-1-marcorr@google.com> (raw) 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. Tested-by: Marc Orr <marcorr@google.com> Cc: stable@vger.kernel.org Signed-off-by: Marc Orr <marcorr@google.com> --- drivers/nvme/host/pci.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 9b1fc8633cfe..8b504ed08321 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -543,11 +543,14 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req) WARN_ON_ONCE(!iod->nents); - 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)); + if (!dma_mapping_error(dev->dev, iod->first_dma)) { + 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)); + } if (iod->npages == 0) @@ -836,8 +839,11 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req, else nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN); - if (!nr_mapped) + if (!nr_mapped) { + iod->first_dma = DMA_MAPPING_ERROR; + iod->npages = -1; goto out; + } iod->use_sgl = nvme_pci_use_sgls(dev, req); if (iod->use_sgl) -- 2.30.0.284.gd98b1dd5eaa7-goog _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme
next reply other threads:[~2021-01-19 19:04 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-19 17:53 Marc Orr [this message] 2021-01-19 17:53 ` [PATCH] nvme: fix handling mapping failure Marc Orr 2021-01-19 18:00 ` Christoph Hellwig 2021-01-19 18:00 ` Christoph Hellwig 2021-01-19 23:12 ` Marc Orr 2021-01-19 23:12 ` Marc Orr
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