On Mon, 20 Jul 2020 13:56:15 +0900 js1304@gmail.com wrote:
Currently, preventing cma area in page allocation is implemented by using current_gfp_context(). However, there are two problems of this implementation.
First, this doesn't work for allocation fastpath. In the fastpath, original gfp_mask is used since current_gfp_context() is introduced in order to control reclaim and it is on slowpath. Second, clearing __GFP_MOVABLE has a side effect to exclude the memory on the ZONE_MOVABLE for allocation target.
To fix these problems, this patch changes the implementation to exclude cma area in page allocation. Main point of this change is using the alloc_flags. alloc_flags is mainly used to control allocation so it fits for excluding cma area in allocation.
What are the end user visible runtime effects of this change?
This is pretty much essential information when proposing a -stable backport.