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b3d40a2b6d
Some places in the kernel don't really expect pageblock_order >= MAX_ORDER, and it looks like this is only possible in corner cases: 1) CONFIG_DEFERRED_STRUCT_PAGE_INIT we'll end up freeing pageblock_order pages via __free_pages_core(), which cannot possibly work. 2) find_zone_movable_pfns_for_nodes() will roundup the ZONE_MOVABLE start PFN to MAX_ORDER_NR_PAGES. Consequently with a bigger pageblock_order, we could have a single pageblock partially managed by two zones. 3) compaction code runs into __fragmentation_index() with order >= MAX_ORDER, when checking WARN_ON_ONCE(order >= MAX_ORDER). [1] 4) mm/page_reporting.c won't be reporting any pages with default page_reporting_order == pageblock_order, as we'll be skipping the reporting loop inside page_reporting_process_zone(). 5) __rmqueue_fallback() will never be able to steal with ALLOC_NOFRAGMENT. pageblock_order >= MAX_ORDER is weird either way: it's a pure optimization for making alloc_contig_range(), as used for allcoation of gigantic pages, a little more reliable to succeed. However, if there is demand for somewhat reliable allocation of gigantic pages, affected setups should be using CMA or boottime allocations instead. So let's make sure that pageblock_order < MAX_ORDER and simplify. [1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com Link: https://lkml.kernel.org/r/20220214174132.219303-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Frank Rowand <frowand.list@gmail.com> Cc: John Garry via iommu <iommu@lists.linux-foundation.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __CMA_H__
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#define __CMA_H__
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/numa.h>
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/*
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* There is always at least global CMA area and a few optional
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* areas configured in kernel .config.
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*/
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#ifdef CONFIG_CMA_AREAS
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#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS)
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#else
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#define MAX_CMA_AREAS (0)
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#endif
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#define CMA_MAX_NAME 64
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/*
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* TODO: once the buddy -- especially pageblock merging and alloc_contig_range()
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* -- can deal with only some pageblocks of a higher-order page being
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* MIGRATE_CMA, we can use pageblock_nr_pages.
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*/
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#define CMA_MIN_ALIGNMENT_PAGES MAX_ORDER_NR_PAGES
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#define CMA_MIN_ALIGNMENT_BYTES (PAGE_SIZE * CMA_MIN_ALIGNMENT_PAGES)
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struct cma;
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extern unsigned long totalcma_pages;
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extern phys_addr_t cma_get_base(const struct cma *cma);
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extern unsigned long cma_get_size(const struct cma *cma);
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extern const char *cma_get_name(const struct cma *cma);
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extern int __init cma_declare_contiguous_nid(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, const char *name, struct cma **res_cma,
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int nid);
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static inline 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, const char *name, struct cma **res_cma)
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{
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return cma_declare_contiguous_nid(base, size, limit, alignment,
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order_per_bit, fixed, name, res_cma, NUMA_NO_NODE);
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}
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extern int 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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const char *name,
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struct cma **res_cma);
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extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align,
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bool no_warn);
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extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count);
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extern bool cma_release(struct cma *cma, const struct page *pages, unsigned long count);
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extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data);
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#endif
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