On Tue 07-03-17 10:57:48, Matthew Wilcox wrote: > On Tue, Mar 07, 2017 at 10:28:41AM -0800, Matthew Wilcox wrote: > > On Tue, Mar 07, 2017 at 03:10:20PM +0100, Michal Hocko wrote: > > > This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to > > > be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM > > > are simplified and drop the flag. > > btw, I had another idea for GFP_HIGHMEM -- remove it when CONFIG_HIGHMEM > isn't enabled. Saves 26 bytes of .text and 64 bytes of .data on my > laptop's kernel build. What do you think? I wouldn't be opposed. The downside would be a slight confusion when printing gfp flags but we already have this for ___GFP_NOLOCKDEP ;) > Also, I suspect the layout of bits is suboptimal from an assembly > language perspective. I still mostly care about x86 which doesn't > benefit, so I'm not inclined to do the work, but certainly ARM, PA-RISC, > SPARC and Itanium would all benefit from having frequently-used bits > (ie those used in GFP_KERNEL and GFP_ATOMIC) placed in the low 8 bits. be careful that there is some elaborate logic around low gfp bits to map to proper zones and ALLOC_ constants. > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 0fe0b6295ab5..d88cb532d7c8 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -16,7 +16,11 @@ struct vm_area_struct; > > /* Plain integer GFP bitmasks. Do not use this directly. */ > #define ___GFP_DMA 0x01u > +#ifdef CONFIG_HIGHMEM > #define ___GFP_HIGHMEM 0x02u > +#else > +#define ___GFP_HIGHMEM 0x0u > +#endif > #define ___GFP_DMA32 0x04u > #define ___GFP_MOVABLE 0x08u > #define ___GFP_RECLAIMABLE 0x10u Anyway, thanks for your review! -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
