On Sun, Oct 11, 2020 at 11:56:35PM -0700, Ira Weiny wrote:

quoted

And I still don't really understand.  After this patchset, there is still code
nearly identical to the above (doing a temporary mapping just for a memcpy) that
would still be using kmap_atomic().

I don't understand.  You mean there would be other call sites calling:

kmap_atomic()
memcpy()
kunmap_atomic()

Yes, there are tons of places that do this.  Try 'git grep -A6 kmap_atomic'
and look for memcpy().

Hence why I'm asking what will be the "recommended" way to do this...
kunmap_thread() or kmap_atomic()?

And since I don't know the call site details if there are kmap_thread() calls
which are better off as kmap_atomic() calls I think it is worth converting
them.  But I made the assumption that kmap users would already be calling
kmap_atomic() if they could (because it is more efficient).

Not necessarily.  In cases where either one is correct, people might not have
put much thought into which of kmap() and kmap_atomic() they are using.

- Eric