Hi Geert,
Thank you for the patch.
On Friday, 20 July 2018 19:16:59 EEST Geert Uytterhoeven wrote:
> When attaching a device to an IOMMU group with
> CONFIG_DEBUG_ATOMIC_SLEEP=y:
>
> BUG: sleeping function called from invalid context at mm/slab.h:421
> in_atomic(): 1, irqs_disabled(): 128, pid: 61, name: kworker/1:1
> ...
> Call trace:
> ...
> arm_lpae_alloc_pgtable+0x114/0x184
> arm_64_lpae_alloc_pgtable_s1+0x2c/0x128
> arm_32_lpae_alloc_pgtable_s1+0x40/0x6c
> alloc_io_pgtable_ops+0x60/0x88
> ipmmu_attach_device+0x140/0x334
>
> ipmmu_attach_device() takes a spinlock, while arm_lpae_alloc_pgtable()
> allocates memory using GFP_KERNEL. Originally, the ipmmu-vmsa driver
> had its own custom page table allocation implementation using
> GFP_ATOMIC, hence the spinlock was fine.
>
> Fix this by replacing the spinlock by a mutex, like the arm-smmu driver
> does.
>
> Fixes: f20ed39f53145e45 ("iommu/ipmmu-vmsa: Use the ARM LPAE page table
> allocator") Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
> ---
> drivers/iommu/ipmmu-vmsa.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
> index 6a0e7142f41bf667..8f54f25404456035 100644
> --- a/drivers/iommu/ipmmu-vmsa.c
> +++ b/drivers/iommu/ipmmu-vmsa.c
> @@ -73,7 +73,7 @@ struct ipmmu_vmsa_domain {
> struct io_pgtable_ops *iop;
>
> unsigned int context_id;
> - spinlock_t lock; /* Protects mappings */
> + struct mutex mutex; /* Protects mappings */
> };
>
> static struct ipmmu_vmsa_domain *to_vmsa_domain(struct iommu_domain *dom)
> @@ -599,7 +599,7 @@ static struct iommu_domain
> *__ipmmu_domain_alloc(unsigned type) if (!domain)
> return NULL;
>
> - spin_lock_init(&domain->lock);
> + mutex_init(&domain->mutex);
>
> return &domain->io_domain;
> }
> @@ -645,7 +645,6 @@ static int ipmmu_attach_device(struct iommu_domain
> *io_domain, struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> struct ipmmu_vmsa_device *mmu = to_ipmmu(dev);
> struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);
> - unsigned long flags;
> unsigned int i;
> int ret = 0;
>
> @@ -654,7 +653,7 @@ static int ipmmu_attach_device(struct iommu_domain
> *io_domain, return -ENXIO;
> }
>
> - spin_lock_irqsave(&domain->lock, flags);
> + mutex_lock(&domain->mutex);
As the ipmmu_attach_device() function is called from a sleepable context this
should be fine.
Reviewed-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
>
> if (!domain->mmu) {
> /* The domain hasn't been used yet, initialize it. */
> @@ -678,7 +677,7 @@ static int ipmmu_attach_device(struct iommu_domain
> *io_domain, } else
> dev_info(dev, "Reusing IPMMU context %u\n", domain->context_id);
>
> - spin_unlock_irqrestore(&domain->lock, flags);
> + mutex_unlock(&domain->mutex);
>
> if (ret < 0)
> return ret;
--
Regards,
Laurent Pinchart
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