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authorDan Williams <dan.j.williams@intel.com>2016-03-18 00:19:41 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-18 01:09:34 +0300
commitb11a7b94100cba5ec926a181894c2897a22651b9 (patch)
tree7fdc2dc46877f6b88ff13d6f71fbb06440796ce4 /include/linux/gfp.h
parentd334c9bcb4aebd0c3e89ee415cba86fa5f0253ee (diff)
downloadlinux-b11a7b94100cba5ec926a181894c2897a22651b9.tar.xz
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/gfp.h')
-rw-r--r--include/linux/gfp.h33
1 files changed, 20 insertions, 13 deletions
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 11d56c6e7ef2..570383a41853 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -331,22 +331,29 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
* 0xe => BAD (MOVABLE+DMA32+HIGHMEM)
* 0xf => BAD (MOVABLE+DMA32+HIGHMEM+DMA)
*
- * ZONES_SHIFT must be <= 2 on 32 bit platforms.
+ * GFP_ZONES_SHIFT must be <= 2 on 32 bit platforms.
*/
-#if 16 * ZONES_SHIFT > BITS_PER_LONG
-#error ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
+#if defined(CONFIG_ZONE_DEVICE) && (MAX_NR_ZONES-1) <= 4
+/* ZONE_DEVICE is not a valid GFP zone specifier */
+#define GFP_ZONES_SHIFT 2
+#else
+#define GFP_ZONES_SHIFT ZONES_SHIFT
+#endif
+
+#if 16 * GFP_ZONES_SHIFT > BITS_PER_LONG
+#error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
#endif
#define GFP_ZONE_TABLE ( \
- (ZONE_NORMAL << 0 * ZONES_SHIFT) \
- | (OPT_ZONE_DMA << ___GFP_DMA * ZONES_SHIFT) \
- | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * ZONES_SHIFT) \
- | (OPT_ZONE_DMA32 << ___GFP_DMA32 * ZONES_SHIFT) \
- | (ZONE_NORMAL << ___GFP_MOVABLE * ZONES_SHIFT) \
- | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * ZONES_SHIFT) \
- | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * ZONES_SHIFT) \
- | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * ZONES_SHIFT) \
+ (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \
+ | (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \
+ | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \
+ | (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \
+ | (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \
+ | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \
+ | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\
+ | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\
)
/*
@@ -371,8 +378,8 @@ static inline enum zone_type gfp_zone(gfp_t flags)
enum zone_type z;
int bit = (__force int) (flags & GFP_ZONEMASK);
- z = (GFP_ZONE_TABLE >> (bit * ZONES_SHIFT)) &
- ((1 << ZONES_SHIFT) - 1);
+ z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
+ ((1 << GFP_ZONES_SHIFT) - 1);
VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
return z;
}