116 lines
4.5 KiB
Diff
116 lines
4.5 KiB
Diff
From: Dan Williams <dan.j.williams@intel.com>
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Date: Wed, 16 Mar 2016 14:16:26 +1100
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Subject: mm: exclude ZONE_DEVICE from GFP_ZONE_TABLE
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Origin: http://article.gmane.org/gmane.linux.kernel.mm/147399
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ZONE_DEVICE (merged in 4.3) and ZONE_CMA (proposed) are examples of new mm
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zones that are bumping up against the current maximum limit of 4 zones,
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i.e. 2 bits in page->flags for the GFP_ZONE_TABLE.
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The GFP_ZONE_TABLE poses an interesting constraint since
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include/linux/gfp.h gets included by the 32-bit portion of a 64-bit build.
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We need to be careful to only build the table for zones that have a
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corresponding gfp_t flag. GFP_ZONES_SHIFT is introduced for this purpose.
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This patch does not attempt to solve the problem of adding a new zone
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that also has a corresponding GFP_ flag.
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Vlastimil points out that ZONE_DEVICE, by depending on x86_64 and
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SPARSEMEM_VMEMMAP implies that SECTIONS_WIDTH is zero. In other words
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even though ZONE_DEVICE does not fit in GFP_ZONE_TABLE it is free to
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consume another bit in page->flags (expand ZONES_WIDTH) with room to
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spare.
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Link: https://bugzilla.kernel.org/show_bug.cgi?id=110931
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Fixes: 033fbae988fc ("mm: ZONE_DEVICE for "device memory"")
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Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Reported-by: Mark <markk@clara.co.uk>
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Reported-by: Vlastimil Babka <vbabka@suse.cz>
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Cc: Mel Gorman <mgorman@suse.de>
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Cc: Rik van Riel <riel@redhat.com>
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Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>
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Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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---
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include/linux/gfp.h | 33 ++++++++++++++++++++-------------
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include/linux/page-flags-layout.h | 2 ++
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mm/Kconfig | 2 --
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3 files changed, 22 insertions(+), 15 deletions(-)
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--- a/include/linux/gfp.h
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+++ b/include/linux/gfp.h
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@@ -329,22 +329,29 @@ static inline bool gfpflags_allow_blocki
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* 0xe => BAD (MOVABLE+DMA32+HIGHMEM)
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* 0xf => BAD (MOVABLE+DMA32+HIGHMEM+DMA)
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*
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- * ZONES_SHIFT must be <= 2 on 32 bit platforms.
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+ * GFP_ZONES_SHIFT must be <= 2 on 32 bit platforms.
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*/
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-#if 16 * ZONES_SHIFT > BITS_PER_LONG
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-#error ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
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+#if defined(CONFIG_ZONE_DEVICE) && (MAX_NR_ZONES-1) <= 4
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+/* ZONE_DEVICE is not a valid GFP zone specifier */
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+#define GFP_ZONES_SHIFT 2
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+#else
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+#define GFP_ZONES_SHIFT ZONES_SHIFT
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+#endif
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+
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+#if 16 * GFP_ZONES_SHIFT > BITS_PER_LONG
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+#error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
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#endif
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#define GFP_ZONE_TABLE ( \
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- (ZONE_NORMAL << 0 * ZONES_SHIFT) \
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- | (OPT_ZONE_DMA << ___GFP_DMA * ZONES_SHIFT) \
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- | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * ZONES_SHIFT) \
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- | (OPT_ZONE_DMA32 << ___GFP_DMA32 * ZONES_SHIFT) \
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- | (ZONE_NORMAL << ___GFP_MOVABLE * ZONES_SHIFT) \
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- | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * ZONES_SHIFT) \
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- | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * ZONES_SHIFT) \
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- | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * ZONES_SHIFT) \
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+ (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \
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+ | (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \
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+ | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \
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+ | (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \
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+ | (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \
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+ | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \
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+ | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\
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+ | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\
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)
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/*
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@@ -369,8 +376,8 @@ static inline enum zone_type gfp_zone(gf
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enum zone_type z;
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int bit = (__force int) (flags & GFP_ZONEMASK);
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- z = (GFP_ZONE_TABLE >> (bit * ZONES_SHIFT)) &
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- ((1 << ZONES_SHIFT) - 1);
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+ z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
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+ ((1 << GFP_ZONES_SHIFT) - 1);
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VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
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return z;
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}
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--- a/include/linux/page-flags-layout.h
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+++ b/include/linux/page-flags-layout.h
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@@ -17,6 +17,8 @@
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#define ZONES_SHIFT 1
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#elif MAX_NR_ZONES <= 4
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#define ZONES_SHIFT 2
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+#elif MAX_NR_ZONES <= 8
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+#define ZONES_SHIFT 3
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#else
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#error ZONES_SHIFT -- too many zones configured adjust calculation
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#endif
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--- a/mm/Kconfig
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+++ b/mm/Kconfig
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@@ -652,8 +652,6 @@ config IDLE_PAGE_TRACKING
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config ZONE_DEVICE
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bool "Device memory (pmem, etc...) hotplug support" if EXPERT
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- default !ZONE_DMA
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- depends on !ZONE_DMA
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depends on MEMORY_HOTPLUG
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depends on MEMORY_HOTREMOVE
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depends on SPARSEMEM_VMEMMAP
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