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![Roman Gushchin](/assets/img/avatar_default.png)
Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
379 lines
10 KiB
C
379 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/percpu-vm.c - vmalloc area based chunk allocation
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*
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* Copyright (C) 2010 SUSE Linux Products GmbH
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* Copyright (C) 2010 Tejun Heo <tj@kernel.org>
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*
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* Chunks are mapped into vmalloc areas and populated page by page.
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* This is the default chunk allocator.
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*/
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static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
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unsigned int cpu, int page_idx)
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{
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/* must not be used on pre-mapped chunk */
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WARN_ON(chunk->immutable);
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return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
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}
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/**
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* pcpu_get_pages - get temp pages array
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*
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* Returns pointer to array of pointers to struct page which can be indexed
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* with pcpu_page_idx(). Note that there is only one array and accesses
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* should be serialized by pcpu_alloc_mutex.
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*
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* RETURNS:
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* Pointer to temp pages array on success.
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*/
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static struct page **pcpu_get_pages(void)
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{
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static struct page **pages;
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size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
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lockdep_assert_held(&pcpu_alloc_mutex);
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if (!pages)
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pages = pcpu_mem_zalloc(pages_size, GFP_KERNEL);
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return pages;
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}
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/**
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* pcpu_free_pages - free pages which were allocated for @chunk
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* @chunk: chunk pages were allocated for
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* @pages: array of pages to be freed, indexed by pcpu_page_idx()
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* @page_start: page index of the first page to be freed
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* @page_end: page index of the last page to be freed + 1
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*
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* Free pages [@page_start and @page_end) in @pages for all units.
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* The pages were allocated for @chunk.
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*/
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static void pcpu_free_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu;
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int i;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page *page = pages[pcpu_page_idx(cpu, i)];
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if (page)
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__free_page(page);
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}
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}
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}
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/**
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* pcpu_alloc_pages - allocates pages for @chunk
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* @chunk: target chunk
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* @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
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* @page_start: page index of the first page to be allocated
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* @page_end: page index of the last page to be allocated + 1
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* @gfp: allocation flags passed to the underlying allocator
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*
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* Allocate pages [@page_start,@page_end) into @pages for all units.
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* The allocation is for @chunk. Percpu core doesn't care about the
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* content of @pages and will pass it verbatim to pcpu_map_pages().
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*/
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static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end,
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gfp_t gfp)
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{
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unsigned int cpu, tcpu;
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int i;
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gfp |= __GFP_HIGHMEM;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
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*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
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if (!*pagep)
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goto err;
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}
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}
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return 0;
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err:
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while (--i >= page_start)
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__free_page(pages[pcpu_page_idx(cpu, i)]);
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for_each_possible_cpu(tcpu) {
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if (tcpu == cpu)
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break;
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for (i = page_start; i < page_end; i++)
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__free_page(pages[pcpu_page_idx(tcpu, i)]);
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}
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return -ENOMEM;
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}
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/**
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* pcpu_pre_unmap_flush - flush cache prior to unmapping
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* @chunk: chunk the regions to be flushed belongs to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages in [@page_start,@page_end) of @chunk are about to be
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* unmapped. Flush cache. As each flushing trial can be very
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* expensive, issue flush on the whole region at once rather than
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* doing it for each cpu. This could be an overkill but is more
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* scalable.
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*/
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static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_cache_vunmap(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
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{
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unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
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}
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/**
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* pcpu_unmap_pages - unmap pages out of a pcpu_chunk
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* @chunk: chunk of interest
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* @pages: pages array which can be used to pass information to free
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* @page_start: page index of the first page to unmap
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* @page_end: page index of the last page to unmap + 1
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*
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* For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
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* Corresponding elements in @pages were cleared by the caller and can
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* be used to carry information to pcpu_free_pages() which will be
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* called after all unmaps are finished. The caller should call
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* proper pre/post flush functions.
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*/
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static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu;
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int i;
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for_each_possible_cpu(cpu) {
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for (i = page_start; i < page_end; i++) {
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struct page *page;
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page = pcpu_chunk_page(chunk, cpu, i);
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WARN_ON(!page);
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pages[pcpu_page_idx(cpu, i)] = page;
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}
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__pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
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page_end - page_start);
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}
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}
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/**
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* pcpu_post_unmap_tlb_flush - flush TLB after unmapping
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* @chunk: pcpu_chunk the regions to be flushed belong to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages [@page_start,@page_end) of @chunk have been unmapped. Flush
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* TLB for the regions. This can be skipped if the area is to be
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* returned to vmalloc as vmalloc will handle TLB flushing lazily.
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*
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* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
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* for the whole region.
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*/
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static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_tlb_kernel_range(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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static int __pcpu_map_pages(unsigned long addr, struct page **pages,
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int nr_pages)
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{
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return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
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PAGE_KERNEL, pages);
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}
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/**
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* pcpu_map_pages - map pages into a pcpu_chunk
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* @chunk: chunk of interest
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* @pages: pages array containing pages to be mapped
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* @page_start: page index of the first page to map
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* @page_end: page index of the last page to map + 1
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*
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* For each cpu, map pages [@page_start,@page_end) into @chunk. The
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* caller is responsible for calling pcpu_post_map_flush() after all
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* mappings are complete.
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*
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* This function is responsible for setting up whatever is necessary for
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* reverse lookup (addr -> chunk).
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*/
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static int pcpu_map_pages(struct pcpu_chunk *chunk,
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struct page **pages, int page_start, int page_end)
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{
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unsigned int cpu, tcpu;
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int i, err;
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for_each_possible_cpu(cpu) {
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err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
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&pages[pcpu_page_idx(cpu, page_start)],
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page_end - page_start);
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if (err < 0)
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goto err;
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for (i = page_start; i < page_end; i++)
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pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
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chunk);
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}
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return 0;
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err:
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for_each_possible_cpu(tcpu) {
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if (tcpu == cpu)
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break;
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__pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
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page_end - page_start);
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}
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pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
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return err;
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}
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/**
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* pcpu_post_map_flush - flush cache after mapping
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* @chunk: pcpu_chunk the regions to be flushed belong to
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* @page_start: page index of the first page to be flushed
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* @page_end: page index of the last page to be flushed + 1
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*
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* Pages [@page_start,@page_end) of @chunk have been mapped. Flush
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* cache.
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*
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* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
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* for the whole region.
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*/
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static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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flush_cache_vmap(
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pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
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pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
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}
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/**
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* pcpu_populate_chunk - populate and map an area of a pcpu_chunk
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* @chunk: chunk of interest
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* @page_start: the start page
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* @page_end: the end page
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* @gfp: allocation flags passed to the underlying memory allocator
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*
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* For each cpu, populate and map pages [@page_start,@page_end) into
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* @chunk.
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*
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* CONTEXT:
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* pcpu_alloc_mutex, does GFP_KERNEL allocation.
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*/
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static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
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int page_start, int page_end, gfp_t gfp)
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{
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struct page **pages;
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pages = pcpu_get_pages();
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if (!pages)
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return -ENOMEM;
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if (pcpu_alloc_pages(chunk, pages, page_start, page_end, gfp))
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return -ENOMEM;
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if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
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pcpu_free_pages(chunk, pages, page_start, page_end);
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return -ENOMEM;
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}
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pcpu_post_map_flush(chunk, page_start, page_end);
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return 0;
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}
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/**
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* pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
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* @chunk: chunk to depopulate
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* @page_start: the start page
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* @page_end: the end page
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*
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* For each cpu, depopulate and unmap pages [@page_start,@page_end)
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* from @chunk.
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*
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* CONTEXT:
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* pcpu_alloc_mutex.
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*/
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static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
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int page_start, int page_end)
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{
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struct page **pages;
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/*
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* If control reaches here, there must have been at least one
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* successful population attempt so the temp pages array must
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* be available now.
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*/
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pages = pcpu_get_pages();
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BUG_ON(!pages);
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/* unmap and free */
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pcpu_pre_unmap_flush(chunk, page_start, page_end);
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pcpu_unmap_pages(chunk, pages, page_start, page_end);
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/* no need to flush tlb, vmalloc will handle it lazily */
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pcpu_free_pages(chunk, pages, page_start, page_end);
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}
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static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
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gfp_t gfp)
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{
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struct pcpu_chunk *chunk;
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struct vm_struct **vms;
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chunk = pcpu_alloc_chunk(type, gfp);
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if (!chunk)
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return NULL;
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vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
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pcpu_nr_groups, pcpu_atom_size);
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if (!vms) {
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pcpu_free_chunk(chunk);
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return NULL;
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}
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chunk->data = vms;
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chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
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pcpu_stats_chunk_alloc();
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trace_percpu_create_chunk(chunk->base_addr);
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return chunk;
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}
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static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
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{
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if (!chunk)
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return;
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pcpu_stats_chunk_dealloc();
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trace_percpu_destroy_chunk(chunk->base_addr);
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if (chunk->data)
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pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
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pcpu_free_chunk(chunk);
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}
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static struct page *pcpu_addr_to_page(void *addr)
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{
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return vmalloc_to_page(addr);
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}
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static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
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{
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/* no extra restriction */
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return 0;
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}
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