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93274f1dd6
Prior to "percpu: implement partial chunk depopulation",
pcpu_depopulate_chunk() was called only on the destruction path. This
meant the virtual address range was on its way back to vmalloc which
will handle flushing the tlbs for us.
However, with pcpu_reclaim_populated(), we are now calling
pcpu_depopulate_chunk() during the active lifecycle of a chunk.
Therefore, we need to flush the tlb as well otherwise we can end up
accessing the wrong page through an invalid tlb mapping as reported in
[1].
[1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/
Fixes: f183324133 ("percpu: implement partial chunk depopulation")
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
131 lines
3.2 KiB
C
131 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/percpu-km.c - kernel memory 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 allocated as a contiguous kernel memory using gfp
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* allocation. This is to be used on nommu architectures.
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*
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* To use percpu-km,
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*
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* - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
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*
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* - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
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* not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
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* fine.
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*
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* - NUMA is not supported. When setting up the first chunk,
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* @cpu_distance_fn should be NULL or report all CPUs to be nearer
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* than or at LOCAL_DISTANCE.
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*
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* - It's best if the chunk size is power of two multiple of
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* PAGE_SIZE. Because each chunk is allocated as a contiguous
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* kernel memory block using alloc_pages(), memory will be wasted if
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* chunk size is not aligned. percpu-km code will whine about it.
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*/
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#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
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#error "contiguous percpu allocation is incompatible with paged first chunk"
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#endif
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#include <linux/log2.h>
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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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/* nothing */
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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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return 0;
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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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/* nada */
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}
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static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
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{
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const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
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struct pcpu_chunk *chunk;
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struct page *pages;
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unsigned long flags;
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int i;
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chunk = pcpu_alloc_chunk(gfp);
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if (!chunk)
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return NULL;
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pages = alloc_pages(gfp, order_base_2(nr_pages));
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if (!pages) {
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pcpu_free_chunk(chunk);
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return NULL;
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}
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for (i = 0; i < nr_pages; i++)
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pcpu_set_page_chunk(nth_page(pages, i), chunk);
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chunk->data = pages;
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chunk->base_addr = page_address(pages);
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spin_lock_irqsave(&pcpu_lock, flags);
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pcpu_chunk_populated(chunk, 0, nr_pages);
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spin_unlock_irqrestore(&pcpu_lock, flags);
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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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const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
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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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__free_pages(chunk->data, order_base_2(nr_pages));
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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 virt_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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size_t nr_pages, alloc_pages;
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/* all units must be in a single group */
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if (ai->nr_groups != 1) {
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pr_crit("can't handle more than one group\n");
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return -EINVAL;
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}
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nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
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alloc_pages = roundup_pow_of_two(nr_pages);
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if (alloc_pages > nr_pages)
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pr_warn("wasting %zu pages per chunk\n",
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alloc_pages - nr_pages);
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return 0;
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}
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static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
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{
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return false;
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}
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