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![Tony Luck](/assets/img/avatar_default.png)
Some high end Intel Xeon systems report uncorrectable memory errors as a recoverable machine check. Linux has included code for some time to process these and just signal the affected processes (or even recover completely if the error was in a read only page that can be replaced by reading from disk). But we have no recovery path for errors encountered during kernel code execution. Except for some very specific cases were are unlikely to ever be able to recover. Enter memory mirroring. Actually 3rd generation of memory mirroing. Gen1: All memory is mirrored Pro: No s/w enabling - h/w just gets good data from other side of the mirror Con: Halves effective memory capacity available to OS/applications Gen2: Partial memory mirror - just mirror memory begind some memory controllers Pro: Keep more of the capacity Con: Nightmare to enable. Have to choose between allocating from mirrored memory for safety vs. NUMA local memory for performance Gen3: Address range partial memory mirror - some mirror on each memory controller Pro: Can tune the amount of mirror and keep NUMA performance Con: I have to write memory management code to implement The current plan is just to use mirrored memory for kernel allocations. This has been broken into two phases: 1) This patch series - find the mirrored memory, use it for boot time allocations 2) Wade into mm/page_alloc.c and define a ZONE_MIRROR to pick up the unused mirrored memory from mm/memblock.c and only give it out to select kernel allocations (this is still being scoped because page_alloc.c is scary). This patch (of 3): Add extra "flags" to memblock to allow selection of memory based on attribute. No functional changes Signed-off-by: Tony Luck <tony.luck@intel.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Hanjun Guo <guohanjun@huawei.com> Cc: Xiexiuqi <xiexiuqi@huawei.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
458 lines
12 KiB
C
458 lines
12 KiB
C
/*
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* Contiguous Memory Allocator
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*
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* Copyright (c) 2010-2011 by Samsung Electronics.
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* Copyright IBM Corporation, 2013
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* Copyright LG Electronics Inc., 2014
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* Written by:
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* Marek Szyprowski <m.szyprowski@samsung.com>
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* Michal Nazarewicz <mina86@mina86.com>
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* Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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* Joonsoo Kim <iamjoonsoo.kim@lge.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License or (at your optional) any later version of the license.
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*/
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#define pr_fmt(fmt) "cma: " fmt
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#ifdef CONFIG_CMA_DEBUG
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#ifndef DEBUG
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# define DEBUG
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#endif
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#endif
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#define CREATE_TRACE_POINTS
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#include <linux/memblock.h>
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#include <linux/err.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/sizes.h>
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#include <linux/slab.h>
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#include <linux/log2.h>
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#include <linux/cma.h>
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#include <linux/highmem.h>
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#include <linux/io.h>
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#include <trace/events/cma.h>
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#include "cma.h"
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struct cma cma_areas[MAX_CMA_AREAS];
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unsigned cma_area_count;
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static DEFINE_MUTEX(cma_mutex);
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phys_addr_t cma_get_base(const struct cma *cma)
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{
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return PFN_PHYS(cma->base_pfn);
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}
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unsigned long cma_get_size(const struct cma *cma)
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{
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return cma->count << PAGE_SHIFT;
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}
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static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
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int align_order)
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{
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if (align_order <= cma->order_per_bit)
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return 0;
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return (1UL << (align_order - cma->order_per_bit)) - 1;
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}
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/*
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* Find a PFN aligned to the specified order and return an offset represented in
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* order_per_bits.
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*/
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static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
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int align_order)
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{
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if (align_order <= cma->order_per_bit)
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return 0;
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return (ALIGN(cma->base_pfn, (1UL << align_order))
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- cma->base_pfn) >> cma->order_per_bit;
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}
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static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
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unsigned long pages)
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{
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return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
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}
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static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
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unsigned int count)
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{
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unsigned long bitmap_no, bitmap_count;
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bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
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bitmap_count = cma_bitmap_pages_to_bits(cma, count);
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mutex_lock(&cma->lock);
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bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
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mutex_unlock(&cma->lock);
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}
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static int __init cma_activate_area(struct cma *cma)
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{
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int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
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unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
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unsigned i = cma->count >> pageblock_order;
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struct zone *zone;
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cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
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if (!cma->bitmap)
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return -ENOMEM;
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WARN_ON_ONCE(!pfn_valid(pfn));
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zone = page_zone(pfn_to_page(pfn));
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do {
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unsigned j;
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base_pfn = pfn;
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for (j = pageblock_nr_pages; j; --j, pfn++) {
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WARN_ON_ONCE(!pfn_valid(pfn));
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/*
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* alloc_contig_range requires the pfn range
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* specified to be in the same zone. Make this
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* simple by forcing the entire CMA resv range
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* to be in the same zone.
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*/
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if (page_zone(pfn_to_page(pfn)) != zone)
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goto err;
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}
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init_cma_reserved_pageblock(pfn_to_page(base_pfn));
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} while (--i);
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mutex_init(&cma->lock);
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#ifdef CONFIG_CMA_DEBUGFS
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INIT_HLIST_HEAD(&cma->mem_head);
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spin_lock_init(&cma->mem_head_lock);
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#endif
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return 0;
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err:
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kfree(cma->bitmap);
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cma->count = 0;
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return -EINVAL;
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}
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static int __init cma_init_reserved_areas(void)
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{
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int i;
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for (i = 0; i < cma_area_count; i++) {
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int ret = cma_activate_area(&cma_areas[i]);
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if (ret)
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return ret;
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}
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return 0;
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}
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core_initcall(cma_init_reserved_areas);
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/**
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* cma_init_reserved_mem() - create custom contiguous area from reserved memory
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* @base: Base address of the reserved area
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* @size: Size of the reserved area (in bytes),
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* @order_per_bit: Order of pages represented by one bit on bitmap.
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* @res_cma: Pointer to store the created cma region.
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*
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* This function creates custom contiguous area from already reserved memory.
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*/
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int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
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unsigned int order_per_bit,
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struct cma **res_cma)
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{
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struct cma *cma;
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phys_addr_t alignment;
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/* Sanity checks */
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if (cma_area_count == ARRAY_SIZE(cma_areas)) {
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pr_err("Not enough slots for CMA reserved regions!\n");
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return -ENOSPC;
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}
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if (!size || !memblock_is_region_reserved(base, size))
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return -EINVAL;
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/* ensure minimal alignment required by mm core */
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alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
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/* alignment should be aligned with order_per_bit */
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if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
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return -EINVAL;
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if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
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return -EINVAL;
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/*
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* Each reserved area must be initialised later, when more kernel
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* subsystems (like slab allocator) are available.
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*/
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cma = &cma_areas[cma_area_count];
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cma->base_pfn = PFN_DOWN(base);
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cma->count = size >> PAGE_SHIFT;
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cma->order_per_bit = order_per_bit;
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*res_cma = cma;
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cma_area_count++;
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totalcma_pages += (size / PAGE_SIZE);
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return 0;
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}
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/**
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* cma_declare_contiguous() - reserve custom contiguous area
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* @base: Base address of the reserved area optional, use 0 for any
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* @size: Size of the reserved area (in bytes),
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* @limit: End address of the reserved memory (optional, 0 for any).
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* @alignment: Alignment for the CMA area, should be power of 2 or zero
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* @order_per_bit: Order of pages represented by one bit on bitmap.
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* @fixed: hint about where to place the reserved area
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* @res_cma: Pointer to store the created cma region.
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*
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* This function reserves memory from early allocator. It should be
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* called by arch specific code once the early allocator (memblock or bootmem)
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* has been activated and all other subsystems have already allocated/reserved
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* memory. This function allows to create custom reserved areas.
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*
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* If @fixed is true, reserve contiguous area at exactly @base. If false,
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* reserve in range from @base to @limit.
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*/
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int __init cma_declare_contiguous(phys_addr_t base,
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phys_addr_t size, phys_addr_t limit,
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phys_addr_t alignment, unsigned int order_per_bit,
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bool fixed, struct cma **res_cma)
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{
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phys_addr_t memblock_end = memblock_end_of_DRAM();
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phys_addr_t highmem_start;
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int ret = 0;
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#ifdef CONFIG_X86
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/*
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* high_memory isn't direct mapped memory so retrieving its physical
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* address isn't appropriate. But it would be useful to check the
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* physical address of the highmem boundary so it's justifiable to get
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* the physical address from it. On x86 there is a validation check for
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* this case, so the following workaround is needed to avoid it.
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*/
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highmem_start = __pa_nodebug(high_memory);
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#else
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highmem_start = __pa(high_memory);
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#endif
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pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
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__func__, &size, &base, &limit, &alignment);
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if (cma_area_count == ARRAY_SIZE(cma_areas)) {
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pr_err("Not enough slots for CMA reserved regions!\n");
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return -ENOSPC;
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}
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if (!size)
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return -EINVAL;
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if (alignment && !is_power_of_2(alignment))
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return -EINVAL;
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/*
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* Sanitise input arguments.
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* Pages both ends in CMA area could be merged into adjacent unmovable
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* migratetype page by page allocator's buddy algorithm. In the case,
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* you couldn't get a contiguous memory, which is not what we want.
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*/
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alignment = max(alignment,
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(phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
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base = ALIGN(base, alignment);
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size = ALIGN(size, alignment);
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limit &= ~(alignment - 1);
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if (!base)
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fixed = false;
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/* size should be aligned with order_per_bit */
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if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
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return -EINVAL;
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/*
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* If allocating at a fixed base the request region must not cross the
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* low/high memory boundary.
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*/
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if (fixed && base < highmem_start && base + size > highmem_start) {
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ret = -EINVAL;
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pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
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&base, &highmem_start);
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goto err;
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}
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/*
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* If the limit is unspecified or above the memblock end, its effective
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* value will be the memblock end. Set it explicitly to simplify further
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* checks.
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*/
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if (limit == 0 || limit > memblock_end)
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limit = memblock_end;
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/* Reserve memory */
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if (fixed) {
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if (memblock_is_region_reserved(base, size) ||
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memblock_reserve(base, size) < 0) {
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ret = -EBUSY;
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goto err;
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}
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} else {
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phys_addr_t addr = 0;
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/*
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* All pages in the reserved area must come from the same zone.
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* If the requested region crosses the low/high memory boundary,
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* try allocating from high memory first and fall back to low
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* memory in case of failure.
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*/
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if (base < highmem_start && limit > highmem_start) {
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addr = memblock_alloc_range(size, alignment,
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highmem_start, limit,
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MEMBLOCK_NONE);
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limit = highmem_start;
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}
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if (!addr) {
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addr = memblock_alloc_range(size, alignment, base,
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limit,
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MEMBLOCK_NONE);
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if (!addr) {
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ret = -ENOMEM;
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goto err;
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}
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}
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/*
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* kmemleak scans/reads tracked objects for pointers to other
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* objects but this address isn't mapped and accessible
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*/
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kmemleak_ignore(phys_to_virt(addr));
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base = addr;
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}
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ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
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if (ret)
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goto err;
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pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
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&base);
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return 0;
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err:
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pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
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return ret;
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}
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/**
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* cma_alloc() - allocate pages from contiguous area
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* @cma: Contiguous memory region for which the allocation is performed.
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* @count: Requested number of pages.
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* @align: Requested alignment of pages (in PAGE_SIZE order).
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*
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* This function allocates part of contiguous memory on specific
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* contiguous memory area.
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*/
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struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align)
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{
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unsigned long mask, offset, pfn, start = 0;
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unsigned long bitmap_maxno, bitmap_no, bitmap_count;
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struct page *page = NULL;
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int ret;
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if (!cma || !cma->count)
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return NULL;
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pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
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count, align);
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if (!count)
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return NULL;
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mask = cma_bitmap_aligned_mask(cma, align);
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offset = cma_bitmap_aligned_offset(cma, align);
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bitmap_maxno = cma_bitmap_maxno(cma);
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bitmap_count = cma_bitmap_pages_to_bits(cma, count);
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for (;;) {
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mutex_lock(&cma->lock);
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bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
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bitmap_maxno, start, bitmap_count, mask,
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offset);
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if (bitmap_no >= bitmap_maxno) {
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mutex_unlock(&cma->lock);
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break;
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}
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bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
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/*
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* It's safe to drop the lock here. We've marked this region for
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* our exclusive use. If the migration fails we will take the
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* lock again and unmark it.
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*/
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mutex_unlock(&cma->lock);
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pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
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mutex_lock(&cma_mutex);
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ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
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mutex_unlock(&cma_mutex);
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if (ret == 0) {
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page = pfn_to_page(pfn);
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break;
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}
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cma_clear_bitmap(cma, pfn, count);
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if (ret != -EBUSY)
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break;
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pr_debug("%s(): memory range at %p is busy, retrying\n",
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__func__, pfn_to_page(pfn));
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/* try again with a bit different memory target */
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start = bitmap_no + mask + 1;
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}
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trace_cma_alloc(page ? pfn : -1UL, page, count, align);
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pr_debug("%s(): returned %p\n", __func__, page);
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return page;
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}
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/**
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* cma_release() - release allocated pages
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* @cma: Contiguous memory region for which the allocation is performed.
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* @pages: Allocated pages.
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* @count: Number of allocated pages.
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*
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* This function releases memory allocated by alloc_cma().
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* It returns false when provided pages do not belong to contiguous area and
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* true otherwise.
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*/
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bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
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{
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unsigned long pfn;
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if (!cma || !pages)
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return false;
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pr_debug("%s(page %p)\n", __func__, (void *)pages);
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pfn = page_to_pfn(pages);
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if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
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return false;
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VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
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free_contig_range(pfn, count);
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cma_clear_bitmap(cma, pfn, count);
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trace_cma_release(pfn, pages, count);
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return true;
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}
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