Messages in this thread | | | Subject | Re: [PATCH] net: don't use kvzalloc for DMA memory | From | Eric Dumazet <> | Date | Wed, 18 Apr 2018 13:38:43 -0700 |
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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 <luto@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)
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