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authorDan Williams <dan.j.williams@intel.com>2016-03-17 14:19:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-17 15:09:34 -0700
commitb11a7b94100cba5ec926a181894c2897a22651b9 (patch)
tree7fdc2dc46877f6b88ff13d6f71fbb06440796ce4 /mm/Kconfig
parentd334c9bcb4aebd0c3e89ee415cba86fa5f0253ee (diff)
downloadlwn-b11a7b94100cba5ec926a181894c2897a22651b9.tar.gz
lwn-b11a7b94100cba5ec926a181894c2897a22651b9.zip
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 <dan.j.williams@intel.com> Reported-by: Mark <markk@clara.co.uk> Reported-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig2
1 files changed, 0 insertions, 2 deletions
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