Re: [Linaro-mm-sig] [PATCH 04/18] dma-fence: prime lockdep annotations

Jason Gunthorpe
2020-06-19T19:51:53Z

On Fri, Jun 19, 2020 at 03:30:32PM -0400, Felix Kuehling wrote:
> We have a potential problem with CPU updating page tables while the GPU
> is retrying on page table entries because 64 bit CPU transactions don't
> arrive in device memory atomically.

Except for 32 bit platforms atomicity is guarenteed if you use uncached
writeq() to aligned addresses..

The linux driver model breaks of the writeX() stuff is not atomic.

Jason