[Devel] [PATCH rh7] fs/fuse/dev: improve ->splice() with fragmented memory

[Andrey Ryabinin]

On 11/29/2017 05:31 PM, Vasily Averin wrote:
> Could you please elaborate, why it should help in reported case?
> It seems for me kvmalloc will push reclaimer first exactly like kmalloc does right now.
> 

Currently we try to allocate possibly high-order page with GFP_KERNEL flags. For order <= PAGE_ALLOC_COSTLY_ORDER
this will loop indefinitely until succeed.

kvmalloc set __GFP_NORETRY, so if high order page isn't available we bail out immediately and try vmalloc()
which will use 0-order pages.