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 --- mm/Kconfig | 2 -- 1 file changed, 2 deletions(-) (limited to 'mm') diff --git a/mm/Kconfig b/mm/Kconfig index c07776503708..520dae6e6ed0 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -651,8 +651,6 @@ config IDLE_PAGE_TRACKING config ZONE_DEVICE bool "Device memory (pmem, etc...) hotplug support" if EXPERT - default !ZONE_DMA - depends on !ZONE_DMA depends on MEMORY_HOTPLUG depends on MEMORY_HOTREMOVE depends on X86_64 #arch_add_memory() comprehends device memory -- cgit v1.2.3