diff options
| 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 /include/linux/page-flags-layout.h | |
| parent | d334c9bcb4aebd0c3e89ee415cba86fa5f0253ee (diff) | |
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 'include/linux/page-flags-layout.h')
| -rw-r--r-- | include/linux/page-flags-layout.h | 2 |
1 files changed, 2 insertions, 0 deletions
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 |