On Fri, Oct 13, 2017 at 05:00:12PM -0700, Nitin Gupta wrote: > On Fri, Sep 29, 2017 at 7:08 AM, Kirill A. Shutemov > <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > With boot-time switching between paging mode we will have variable > > MAX_PHYSMEM_BITS. > > > > Let's use the maximum variable possible for CONFIG_X86_5LEVEL=y > > configuration to define zsmalloc data structures. > > > > The patch introduces MAX_POSSIBLE_PHYSMEM_BITS to cover such case. > > It also suits well to handle PAE special case. > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > > Cc: Minchan Kim <minchan@xxxxxxxxxx> > > Cc: Nitin Gupta <ngupta@xxxxxxxxxx> > > Cc: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx> > > --- > > arch/x86/include/asm/pgtable-3level_types.h | 1 + > > arch/x86/include/asm/pgtable_64_types.h | 2 ++ > > mm/zsmalloc.c | 13 +++++++------ > > 3 files changed, 10 insertions(+), 6 deletions(-) > > > > diff --git a/arch/x86/include/asm/pgtable-3level_types.h b/arch/x86/include/asm/pgtable-3level_types.h > > index b8a4341faafa..3fe1d107a875 100644 > > --- a/arch/x86/include/asm/pgtable-3level_types.h > > +++ b/arch/x86/include/asm/pgtable-3level_types.h > > @@ -43,5 +43,6 @@ typedef union { > > */ > > #define PTRS_PER_PTE 512 > > > > +#define MAX_POSSIBLE_PHYSMEM_BITS 36 > > > > #endif /* _ASM_X86_PGTABLE_3LEVEL_DEFS_H */ > > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > > index 06470da156ba..39075df30b8a 100644 > > --- a/arch/x86/include/asm/pgtable_64_types.h > > +++ b/arch/x86/include/asm/pgtable_64_types.h > > @@ -39,6 +39,8 @@ typedef struct { pteval_t pte; } pte_t; > > #define P4D_SIZE (_AC(1, UL) << P4D_SHIFT) > > #define P4D_MASK (~(P4D_SIZE - 1)) > > > > +#define MAX_POSSIBLE_PHYSMEM_BITS 52 > > + > > #else /* CONFIG_X86_5LEVEL */ > > > > /* > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > > index 7c38e850a8fc..7bde01c55c90 100644 > > --- a/mm/zsmalloc.c > > +++ b/mm/zsmalloc.c > > @@ -82,18 +82,19 @@ > > * This is made more complicated by various memory models and PAE. > > */ > > > > -#ifndef MAX_PHYSMEM_BITS > > -#ifdef CONFIG_HIGHMEM64G > > -#define MAX_PHYSMEM_BITS 36 > > -#else /* !CONFIG_HIGHMEM64G */ > > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS > > +#ifdef MAX_PHYSMEM_BITS > > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS > > +#else > > /* > > * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just > > * be PAGE_SHIFT > > */ > > -#define MAX_PHYSMEM_BITS BITS_PER_LONG > > +#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG > > #endif > > #endif > > -#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT) > > + > > +#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > > > > > I think we can avoid using this new constant in zsmalloc. > > The reason for trying to save on MAX_PHYSMEM_BITS is just to gain more > bits for OBJ_INDEX_BITS which would reduce ZS_MIN_ALLOC_SIZE. However, > for all practical values of ZS_MAX_PAGES_PER_ZSPAGE, this min size > would remain 32 bytes. > > So, we can unconditionally use MAX_PHYSMEM_BITS = BITS_PER_LONG and > thus OBJ_INDEX_BITS = PAGE_SHIFT. As you understand the topic better than me, could you prepare the patch? -- Kirill A. Shutemov -- 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>