kernel spew from nouveau/ swiotlb

From: Mike Galbraith
Date: Thu May 10 2018 - 05:10:54 EST


Greetings,

When box is earning its keep, nouveau/swiotlb grumble.. a LOT. The
below is from master.today.

[12594.640959] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12594.693000] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12594.713787] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12594.743413] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12594.796740] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12607.000774] swiotlb_tbl_map_single: 54 callbacks suppressed
[12607.000776] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12607.347941] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
[12608.677038] nouveau 0000:01:00.0: swiotlb buffer is full (sz: 2097152 bytes)
homer:/novell/ssh # dmesg|grep 'swiotlb buffer is full'|wc -l
2052
homer:/novell/ssh # dmesg|grep 'callbacks suppressed'|wc -l
171

lib/swiotlb.c:
573 not_found:
574         spin_unlock_irqrestore(&io_tlb_lock, flags);
575         if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
576                 dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);

Does nouveau perhaps want one of those DMA_ATTR_NO_WARN thingies?

-Mike