On Wed, Apr 18, 2018 at 01:38:43PM -0700, Eric Dumazet wrote: > > > On 04/18/2018 10:55 AM, Michael S. Tsirkin wrote: > > > Imagine you want to pass some data to card. > > Natural thing is to just put it in a variable and start DMA. > > However DMA API disallows stack access nowdays, > > so it's natural to put this within struct device. > > > > See e.g. > > > > commit a725ee3e44e39dab1ec82cc745899a785d2a555e > > Author: Andy Lutomirski <l...@kernel.org> > > Date: Mon Jul 18 15:34:49 2016 -0700 > > > > virtio-net: Remove more stack DMA > > > > Andy just moved the problem to another one, since at that time we already > had vmalloc() fallback for at least 2 years. > > Note that my original patch had : > > p = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); > if (!p) > p = vzalloc(alloc_size); > > So really, normal (less than PAGE_SIZE) allocations would have > almost-zero-chance to end up to vmalloc(one_page)
Thanks Eric, I'll fix virtio. -- MST
