From b11a7b94100cba5ec926a181894c2897a22651b9 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 17 Mar 2016 14:19:41 -0700 Subject: mm: exclude ZONE_DEVICE from GFP_ZONE_TABLE ZONE_DEVICE (merged in 4.3) and ZONE_CMA (proposed) are examples of new mm zones that are bumping up against the current maximum limit of 4 zones, i.e. 2 bits in page->flags for the GFP_ZONE_TABLE. The GFP_ZONE_TABLE poses an interesting constraint since include/linux/gfp.h gets included by the 32-bit portion of a 64-bit build. We need to be careful to only build the table for zones that have a corresponding gfp_t flag. GFP_ZONES_SHIFT is introduced for this purpose. This patch does not attempt to solve the problem of adding a new zone that also has a corresponding GFP_ flag. Vlastimil points out that ZONE_DEVICE, by depending on x86_64 and SPARSEMEM_VMEMMAP implies that SECTIONS_WIDTH is zero. In other words even though ZONE_DEVICE does not fit in GFP_ZONE_TABLE it is free to consume another bit in page->flags (expand ZONES_WIDTH) with room to spare. Link: https://bugzilla.kernel.org/show_bug.cgi?id=110931 Fixes: 033fbae988fc ("mm: ZONE_DEVICE for "device memory"") Signed-off-by: Dan Williams Reported-by: Mark Reported-by: Vlastimil Babka Cc: Mel Gorman Cc: Rik van Riel Cc: Joonsoo Kim Cc: Dave Hansen Cc: Sudip Mukherjee Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page-flags-layout.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/page-flags-layout.h') diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h index da523661500a..77b078c103b2 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -17,6 +17,8 @@ #define ZONES_SHIFT 1 #elif MAX_NR_ZONES <= 4 #define ZONES_SHIFT 2 +#elif MAX_NR_ZONES <= 8 +#define ZONES_SHIFT 3 #else #error ZONES_SHIFT -- too many zones configured adjust calculation #endif -- cgit v1.2.3