6.14-stable review patch. If anyone has any objections, please let me know.
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From: Nicolin Chen nicolinc@nvidia.com
commit 767e22001dfce64cc03b7def1562338591ab6031 upstream.
Two WARNINGs are observed when SMMU driver rolls back upon failure: arm-smmu-v3.9.auto: Failed to register iommu arm-smmu-v3.9.auto: probe with driver arm-smmu-v3 failed with error -22 ------------[ cut here ]------------ WARNING: CPU: 5 PID: 1 at kernel/dma/mapping.c:74 dmam_free_coherent+0xc0/0xd8 Call trace: dmam_free_coherent+0xc0/0xd8 (P) tegra241_vintf_free_lvcmdq+0x74/0x188 tegra241_cmdqv_remove_vintf+0x60/0x148 tegra241_cmdqv_remove+0x48/0xc8 arm_smmu_impl_remove+0x28/0x60 devm_action_release+0x1c/0x40 ------------[ cut here ]------------ 128 pages are still in use! WARNING: CPU: 16 PID: 1 at mm/page_alloc.c:6902 free_contig_range+0x18c/0x1c8 Call trace: free_contig_range+0x18c/0x1c8 (P) cma_release+0x154/0x2f0 dma_free_contiguous+0x38/0xa0 dma_direct_free+0x10c/0x248 dma_free_attrs+0x100/0x290 dmam_free_coherent+0x78/0xd8 tegra241_vintf_free_lvcmdq+0x74/0x160 tegra241_cmdqv_remove+0x98/0x198 arm_smmu_impl_remove+0x28/0x60 devm_action_release+0x1c/0x40
This is because the LVCMDQ queue memory are managed by devres, while that dmam_free_coherent() is called in the context of devm_action_release().
Jason pointed out that "arm_smmu_impl_probe() has mis-ordered the devres callbacks if ops->device_remove() is going to be manually freeing things that probe allocated": https://lore.kernel.org/linux-iommu/20250407174408.GB1722458@nvidia.com/
In fact, tegra241_cmdqv_init_structures() only allocates memory resources which means any failure that it generates would be similar to -ENOMEM, so there is no point in having that "falling back to standard SMMU" routine, as the standard SMMU would likely fail to allocate memory too.
Remove the unwind part in tegra241_cmdqv_init_structures(), and return a proper error code to ask SMMU driver to call tegra241_cmdqv_remove() via impl_ops->device_remove(). Then, drop tegra241_vintf_free_lvcmdq() since devres will take care of that.
Fixes: 483e0bd8883a ("iommu/tegra241-cmdqv: Do not allocate vcmdq until dma_set_mask_and_coherent") Cc: stable@vger.kernel.org Suggested-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Link: https://lore.kernel.org/r/20250407201908.172225-1-nicolinc@nvidia.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 32 +++---------------------- 1 file changed, 5 insertions(+), 27 deletions(-)
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c +++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c @@ -487,17 +487,6 @@ static int tegra241_cmdqv_hw_reset(struc
/* VCMDQ Resource Helpers */
-static void tegra241_vcmdq_free_smmu_cmdq(struct tegra241_vcmdq *vcmdq) -{ - struct arm_smmu_queue *q = &vcmdq->cmdq.q; - size_t nents = 1 << q->llq.max_n_shift; - size_t qsz = nents << CMDQ_ENT_SZ_SHIFT; - - if (!q->base) - return; - dmam_free_coherent(vcmdq->cmdqv->smmu.dev, qsz, q->base, q->base_dma); -} - static int tegra241_vcmdq_alloc_smmu_cmdq(struct tegra241_vcmdq *vcmdq) { struct arm_smmu_device *smmu = &vcmdq->cmdqv->smmu; @@ -560,7 +549,8 @@ static void tegra241_vintf_free_lvcmdq(s struct tegra241_vcmdq *vcmdq = vintf->lvcmdqs[lidx]; char header[64];
- tegra241_vcmdq_free_smmu_cmdq(vcmdq); + /* Note that the lvcmdq queue memory space is managed by devres */ + tegra241_vintf_deinit_lvcmdq(vintf, lidx);
dev_dbg(vintf->cmdqv->dev, @@ -768,13 +758,13 @@ static int tegra241_cmdqv_init_structure
vintf = kzalloc(sizeof(*vintf), GFP_KERNEL); if (!vintf) - goto out_fallback; + return -ENOMEM;
/* Init VINTF0 for in-kernel use */ ret = tegra241_cmdqv_init_vintf(cmdqv, 0, vintf); if (ret) { dev_err(cmdqv->dev, "failed to init vintf0: %d\n", ret); - goto free_vintf; + return ret; }
/* Preallocate logical VCMDQs to VINTF0 */ @@ -783,24 +773,12 @@ static int tegra241_cmdqv_init_structure
vcmdq = tegra241_vintf_alloc_lvcmdq(vintf, lidx); if (IS_ERR(vcmdq)) - goto free_lvcmdq; + return PTR_ERR(vcmdq); }
/* Now, we are ready to run all the impl ops */ smmu->impl_ops = &tegra241_cmdqv_impl_ops; return 0; - -free_lvcmdq: - for (lidx--; lidx >= 0; lidx--) - tegra241_vintf_free_lvcmdq(vintf, lidx); - tegra241_cmdqv_deinit_vintf(cmdqv, vintf->idx); -free_vintf: - kfree(vintf); -out_fallback: - dev_info(smmu->impl_dev, "Falling back to standard SMMU CMDQ\n"); - smmu->options &= ~ARM_SMMU_OPT_TEGRA241_CMDQV; - tegra241_cmdqv_remove(smmu); - return 0; }
#ifdef CONFIG_IOMMU_DEBUGFS