174 lines
6.5 KiB
Diff
174 lines
6.5 KiB
Diff
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From 8b368e8e961944105945fbe36f3f264252bfd19a Mon Sep 17 00:00:00 2001
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From: Dan Williams <dan.j.williams@intel.com>
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Date: Thu, 25 Feb 2016 01:02:30 +0000
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Subject: [PATCH] mm: CONFIG_NR_ZONES_EXTENDED
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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. When adding a zone this equation still needs
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to be satisified:
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SECTIONS_WIDTH + ZONES_WIDTH + NODES_SHIFT + LAST_CPUPID_SHIFT
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<= BITS_PER_LONG - NR_PAGEFLAGS
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ZONE_DEVICE currently tries to satisfy this equation by requiring that
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ZONE_DMA be disabled, but this is untenable given generic kernels want to
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support ZONE_DEVICE and ZONE_DMA simultaneously. ZONE_CMA would like to
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increase the amount of memory covered per section, but that limits the
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minimum granularity at which consecutive memory ranges can be added via
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devm_memremap_pages().
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The trade-off of what is acceptable to sacrifice depends heavily on the
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platform. For example, ZONE_CMA is targeted for 32-bit platforms where
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page->flags is constrained, but those platforms likely do not care about
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the minimum granularity of memory hotplug. A big iron machine with 1024
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numa nodes can likely sacrifice ZONE_DMA where a general purpose
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distribution kernel can not.
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CONFIG_NR_ZONES_EXTENDED is a configuration symbol that gets selected when
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the number of configured zones exceeds 4. It documents the configuration
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symbols and definitions that get modified when ZONES_WIDTH is greater than
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2.
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For now, it steals a bit from NODES_SHIFT. Later on it can be used to
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document the definitions that get modified when a 32-bit configuration
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wants more zone bits.
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Note that 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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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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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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arch/x86/Kconfig | 6 ++++--
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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 | 7 +++++--
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4 files changed, 31 insertions(+), 17 deletions(-)
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diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
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index 3fef519..b94704a 100644
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -1409,8 +1409,10 @@ config NUMA_EMU
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config NODES_SHIFT
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int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
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- range 1 10
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- default "10" if MAXSMP
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+ range 1 10 if !NR_ZONES_EXTENDED
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+ range 1 9 if NR_ZONES_EXTENDED
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+ default "10" if MAXSMP && !NR_ZONES_EXTENDED
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+ default "9" if MAXSMP && NR_ZONES_EXTENDED
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default "6" if X86_64
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default "3"
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depends on NEED_MULTIPLE_NODES
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diff --git a/include/linux/gfp.h b/include/linux/gfp.h
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index af1f2b2..d201d8a 100644
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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_blocking(const gfp_t gfp_flags)
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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(gfp_t flags)
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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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diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
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index da52366..77b078c 100644
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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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diff --git a/mm/Kconfig b/mm/Kconfig
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index 031a329..7826216 100644
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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"
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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 X86_64 #arch_add_memory() comprehends device memory
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@@ -667,5 +665,10 @@ config ZONE_DEVICE
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If FS_DAX is enabled, then say Y.
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+config NR_ZONES_EXTENDED
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+ bool
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+ default n if !64BIT
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+ default y if ZONE_DEVICE && ZONE_DMA && ZONE_DMA32
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+
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config FRAME_VECTOR
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bool
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--
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2.5.0
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