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Subject[PATCH] iommu/ipmmu-vmsa: Fix allocation in atomic context
Date
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+renesas@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);

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;
--
2.17.1
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