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b=xpU+yrOeNxAR9I+1erV0Pgmk3bNumU3mewZqDbRyPdKN+qAo+ckyErP6eqyL+outRKlvz747wZGx5Xi13W9HaGvM44rYWqEmIwQ0TcGOAHJrLvzON9Ilf6O7x1a6RBYQjdN2sBvIi4Pb27apK5mXYm0tWCtYLUP8G7Ug/POs/jk= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from CY8PR12MB7170.namprd12.prod.outlook.com (2603:10b6:930:5a::18) by BL4PR12MB9505.namprd12.prod.outlook.com (2603:10b6:208:591::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.202.18; Mon, 13 Jul 2026 10:13:33 +0000 Received: from CY8PR12MB7170.namprd12.prod.outlook.com ([fe80::7565:bdd3:383a:de5f]) by CY8PR12MB7170.namprd12.prod.outlook.com ([fe80::7565:bdd3:383a:de5f%4]) with mapi id 15.21.0202.018; Mon, 13 Jul 2026 10:13:33 +0000 Message-ID: <5538f1c3-a665-42c9-ae96-89e2867ab470@amd.com> Date: Mon, 13 Jul 2026 18:13:27 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] iommu/dma: simplify dma_iova_destroy() and drop the free_iova helper To: Marek Szyprowski Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Ray.Huang@amd.com, robin.murphy@arm.com, joro@8bytes.org, will@kernel.org, leonro@nvidia.com References: <20260703033729.455358-1-honghuan@amd.com> <8c254797-a349-47a0-be4a-86a8ad09cf56@samsung.com> Content-Language: en-US From: "Huang, Honglei" In-Reply-To: <8c254797-a349-47a0-be4a-86a8ad09cf56@samsung.com> Content-Type: text/plain; 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And it frees using the unmapped @mapped_len, which for a >> partially linked reservation is smaller than the reserved size. This >> results in a benign waste as pointed out by Robin, not a leak. So this is >> a cleanup, not a fix. >> >> Drop the duplicated free path. Fold __iommu_dma_iova_unlink into >> dma_iova_unlink and remove the free_iova parameter so it only unmaps. >> dma_iova_destroy then unlinks the mapped range if mapped_len is set and >> unconditionally calls dma_iova_free, which frees the whole reservation >> via dma_iova_size. The freed size now always matches the reserved size, >> and destroy reads as unlink then free. >> >> Note that dma_iova_destroy() no longer routes the free through the flush >> queue; teardown now unmaps synchronously and frees directly, matching >> dma_iova_free(). >> >> No functional change intended for callers. >> >> Suggested-by: Leon Romanovsky >> Signed-off-by: Honglei Huang > > > Applied to dma-mapping-for-next. Thanks! Thanks for the merging! Regards, Honglei > > >> --- >> Changes since v1: >> - Reframed from an IOVA-leak fix into a cleanup; dropped Fixes:/Cc: stable. >> - Fold the free_iova helper into dma_iova_unlink() according to Leon's >> diff, so destroy is unlink + dma_iova_free(). Added Suggested-by: Leon. >> >> drivers/iommu/dma-iommu.c | 57 +++++++++++++++------------------------ >> 1 file changed, 22 insertions(+), 35 deletions(-) >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index 9abaec0703e..5598ed4bff7 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -2068,10 +2068,20 @@ static void iommu_dma_iova_unlink_range_slow(struct device *dev, >> arch_sync_dma_flush(); >> } >> >> -static void __iommu_dma_iova_unlink(struct device *dev, >> - struct dma_iova_state *state, size_t offset, size_t size, >> - enum dma_data_direction dir, unsigned long attrs, >> - bool free_iova) >> +/** >> + * dma_iova_unlink - Unlink a range of IOVA space >> + * @dev: DMA device >> + * @state: IOVA state >> + * @offset: offset into the IOVA state to unlink >> + * @size: size of the buffer >> + * @dir: DMA direction >> + * @attrs: attributes of mapping properties >> + * >> + * Unlink a range of IOVA space for the given IOVA state. >> + */ >> +void dma_iova_unlink(struct device *dev, struct dma_iova_state *state, >> + size_t offset, size_t size, enum dma_data_direction dir, >> + unsigned long attrs) >> { >> struct iommu_domain *domain = iommu_get_dma_domain(dev); >> struct iommu_dma_cookie *cookie = domain->iova_cookie; >> @@ -2087,35 +2097,13 @@ static void __iommu_dma_iova_unlink(struct device *dev, >> iommu_dma_iova_unlink_range_slow(dev, addr, size, dir, attrs); >> >> iommu_iotlb_gather_init(&iotlb_gather); >> - iotlb_gather.queued = free_iova && READ_ONCE(cookie->fq_domain); >> >> size = iova_align(iovad, size + iova_start_pad); >> addr -= iova_start_pad; >> unmapped = iommu_unmap_fast(domain, addr, size, &iotlb_gather); >> WARN_ON(unmapped != size); >> >> - if (!iotlb_gather.queued) >> - iommu_iotlb_sync(domain, &iotlb_gather); >> - if (free_iova) >> - iommu_dma_free_iova(domain, addr, size, &iotlb_gather); >> -} >> - >> -/** >> - * dma_iova_unlink - Unlink a range of IOVA space >> - * @dev: DMA device >> - * @state: IOVA state >> - * @offset: offset into the IOVA state to unlink >> - * @size: size of the buffer >> - * @dir: DMA direction >> - * @attrs: attributes of mapping properties >> - * >> - * Unlink a range of IOVA space for the given IOVA state. >> - */ >> -void dma_iova_unlink(struct device *dev, struct dma_iova_state *state, >> - size_t offset, size_t size, enum dma_data_direction dir, >> - unsigned long attrs) >> -{ >> - __iommu_dma_iova_unlink(dev, state, offset, size, dir, attrs, false); >> + iommu_iotlb_sync(domain, &iotlb_gather); >> } >> EXPORT_SYMBOL_GPL(dma_iova_unlink); >> >> @@ -2136,14 +2124,13 @@ void dma_iova_destroy(struct device *dev, struct dma_iova_state *state, >> unsigned long attrs) >> { >> if (mapped_len) >> - __iommu_dma_iova_unlink(dev, state, 0, mapped_len, dir, attrs, >> - true); >> - else >> - /* >> - * We can be here if first call to dma_iova_link() failed and >> - * there is nothing to unlink, so let's be more clear. >> - */ >> - dma_iova_free(dev, state); >> + dma_iova_unlink(dev, state, 0, mapped_len, dir, attrs); >> + >> + /* >> + * We can be here if the first call to dma_iova_link() failed and >> + * there is nothing to unlink, so let's be more clear. >> + */ >> + dma_iova_free(dev, state); >> } >> EXPORT_SYMBOL_GPL(dma_iova_destroy); >> >> >> base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 > > Best regards