Re: [PATCH -v2] mm: Don't use radix tree writeback tags for pages in swap cache

[Andi Kleen]

Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> writes:
>
> __GFP_BITS_SHIFT + 5 (AS_NO_WRITEBACK_TAGS) = 31
>
> mapping->flags is a combination of AS and GFP flags so increasing
> __GFP_BITS_SHIFT overflows mapping->flags on 32-bit as gfp_t is an
> unsigned int.

Couldn't we just split mapping->flags into two fields?
I'm sure more GFP bits will be needed eventually.

-Andi