This prevents flooding the logs with 'iommu_alloc failed' messages
while I/O is performed (normally) to very fast devices (e.g. NVMe).
That error is not necessarily a problem; device drivers can retry
later / reschedule the requests for which the allocation failed,
and handle things gracefully for the caller stack on top of them.
This helps at least with NVMe devices without "64-bit"/direct DMA
window scenarios (e.g., systems with more than a few terabytes of
memory, on which DDW cannot be enabled, currently), where just an
'dd' command can trigger errors.
# dd if=/dev/zero of=/dev/nvme0n1p1 bs=64k count=512k
<...>
# echo $?
0
# dmesg
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c000000151c90000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c000000151c90000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c000000151c90000 npages 16
<...>
ppc_iommu_map_sg: 8186 callbacks suppressed
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c0000000fa5c0000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c000000100440000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c000000100440000 npages 16
<...>
ppc_iommu_map_sg: 5707 callbacks suppressed
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c0000000b5f50000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c0000000b5c60000 npages 16
nvme 0000:00:06.0: iommu_alloc failed, tbl c0000001fa67c520 vaddr
c0000000b4b30000 npages 16
<...>
Tested on next-20160609.
Signed-off-by: Mauricio Faria de Oliveira <mauri...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/iommu.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index a8e3490..b585bdc 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -479,10 +479,9 @@ int ppc_iommu_map_sg(struct device *dev, struct
iommu_table *tbl,
/* Handle failure */
if (unlikely(entry == DMA_ERROR_CODE)) {
- if (printk_ratelimit())
- dev_info(dev, "iommu_alloc failed, tbl %p "
- "vaddr %lx npages %lu\n", tbl, vaddr,
- npages);
+ dev_dbg_ratelimited(dev, "iommu_alloc failed, tbl %p "
+ "vaddr %lx npages %lu\n", tbl, vaddr,
+ npages);
goto failure;
}
@@ -776,11 +775,9 @@ dma_addr_t iommu_map_page(struct device *dev, struct
iommu_table *tbl,
mask >> tbl->it_page_shift, align,
attrs);
if (dma_handle == DMA_ERROR_CODE) {
- if (printk_ratelimit()) {
- dev_info(dev, "iommu_alloc failed, tbl %p "
- "vaddr %p npages %d\n", tbl, vaddr,
- npages);
- }
+ dev_dbg_ratelimited(dev, "iommu_alloc failed, tbl %p "
+ "vaddr %p npages %d\n", tbl, vaddr,
+ npages);
} else
dma_handle |= (uaddr & ~IOMMU_PAGE_MASK(tbl));
}
--
1.8.3.1
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