Re: [PATCH net-next 1/2] tcp: add TCP_ZEROCOPY_RECEIVE support for zerocopy receive

On 04/25/2018 09:04 AM, Matthew Wilcox wrote:

If you don't zap the page range, any of the CPUs in the system where
any thread in this task have ever run may have a TLB entry pointing to
this page ... if the page is being recycled into the page allocator,
then that page might end up as a slab page or page table or page cache
while the other CPU still have access to it.

Yes, this makes sense.

You could hang onto the page until you've built up a sufficiently large
batch, then bulk-invalidate all of the TLB entries, but we start to get
into weirdnesses on different CPU architectures.

zap_page_range() is already doing a bulk-invalidate,
so maybe vm_replace_page() wont bring serious improvement if we end-up doing same dance.

Thanks.