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| author | Dan Williams <dan.j.williams@intel.com> | 2016-03-17 14:19:41 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-17 15:09:34 -0700 |
| commit | b11a7b94100cba5ec926a181894c2897a22651b9 (patch) | |
| tree | 7fdc2dc46877f6b88ff13d6f71fbb06440796ce4 /mm/Kconfig | |
| parent | d334c9bcb4aebd0c3e89ee415cba86fa5f0253ee (diff) | |
| download | lwn-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/Kconfig | 2 |
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 |