On Tue, 10 Apr 2018 20:10:20 +0200, Christoph Hellwig wrote: > > On Tue, Apr 10, 2018 at 06:50:04PM +0100, Robin Murphy wrote: > > In the first one, the machine appears to have enough RAM that most of it is > > beyond the device's 36-bit DMA mask, thus it's fairly likely for the > > initial direct alloc to come back with something unsuitable. > > But we should try a GFP_DMA32 allocation first, so this is a bit > surprising.
Hm, do we really try that? Through a quick glance, dma_alloc_coherent_gfp_flags() gives GFP_DMA32 only when coherent mask <= DMA_BIT_MASK(32); in the case of iwlwifi, it's 36bit, so GFP_DMA isn't set. We had a fallback allocation with GFP_DMA32 in the past, but this seems gone long time ago along with cleanups (commit c647c3bb2d16). But I haven't followed about this topic for long time, so I might have missed obviously... thanks, Takashi _______________________________________________ iommu mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/iommu