Merge branch 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
Pull percpu fixes from Tejun Heo: "While adding GFP_ATOMIC support to the percpu allocator, the synchronization for the fast-path which doesn't require external allocations was separated into pcpu_lock. Unfortunately, it incorrectly decoupled async paths and percpu chunks could get destroyed while still being operated on. This contains two patches to fix the bug" * 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: fix synchronization between synchronous map extension and chunk destruction percpu: fix synchronization between chunk->map_extend_work and chunk destruction
This commit is contained in:
Linus Torvalds
Коммит
db06d759d6
73
mm/percpu.c
73
mm/percpu.c
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@ -112,7 +112,7 @@ struct pcpu_chunk {
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int map_used; /* # of map entries used before the sentry */
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int map_alloc; /* # of map entries allocated */
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int *map; /* allocation map */
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struct work_struct map_extend_work;/* async ->map[] extension */
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struct list_head map_extend_list;/* on pcpu_map_extend_chunks */
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void *data; /* chunk data */
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int first_free; /* no free below this */
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@ -162,10 +162,13 @@ static struct pcpu_chunk *pcpu_reserved_chunk;
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static int pcpu_reserved_chunk_limit;
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static DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
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static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop */
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static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
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static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
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/* chunks which need their map areas extended, protected by pcpu_lock */
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static LIST_HEAD(pcpu_map_extend_chunks);
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/*
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* The number of empty populated pages, protected by pcpu_lock. The
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* reserved chunk doesn't contribute to the count.
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@ -395,13 +398,19 @@ static int pcpu_need_to_extend(struct pcpu_chunk *chunk, bool is_atomic)
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{
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int margin, new_alloc;
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lockdep_assert_held(&pcpu_lock);
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if (is_atomic) {
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margin = 3;
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if (chunk->map_alloc <
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chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW &&
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pcpu_async_enabled)
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schedule_work(&chunk->map_extend_work);
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chunk->map_used + PCPU_ATOMIC_MAP_MARGIN_LOW) {
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if (list_empty(&chunk->map_extend_list)) {
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list_add_tail(&chunk->map_extend_list,
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&pcpu_map_extend_chunks);
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pcpu_schedule_balance_work();
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}
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}
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} else {
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margin = PCPU_ATOMIC_MAP_MARGIN_HIGH;
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}
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@ -435,6 +444,8 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
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size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
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unsigned long flags;
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lockdep_assert_held(&pcpu_alloc_mutex);
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new = pcpu_mem_zalloc(new_size);
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if (!new)
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return -ENOMEM;
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@ -467,20 +478,6 @@ out_unlock:
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return 0;
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}
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static void pcpu_map_extend_workfn(struct work_struct *work)
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{
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struct pcpu_chunk *chunk = container_of(work, struct pcpu_chunk,
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map_extend_work);
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int new_alloc;
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spin_lock_irq(&pcpu_lock);
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new_alloc = pcpu_need_to_extend(chunk, false);
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spin_unlock_irq(&pcpu_lock);
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if (new_alloc)
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pcpu_extend_area_map(chunk, new_alloc);
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}
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/**
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* pcpu_fit_in_area - try to fit the requested allocation in a candidate area
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* @chunk: chunk the candidate area belongs to
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@ -740,7 +737,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
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chunk->map_used = 1;
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INIT_LIST_HEAD(&chunk->list);
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INIT_WORK(&chunk->map_extend_work, pcpu_map_extend_workfn);
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INIT_LIST_HEAD(&chunk->map_extend_list);
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chunk->free_size = pcpu_unit_size;
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chunk->contig_hint = pcpu_unit_size;
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@ -895,6 +892,9 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
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return NULL;
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}
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if (!is_atomic)
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mutex_lock(&pcpu_alloc_mutex);
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spin_lock_irqsave(&pcpu_lock, flags);
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/* serve reserved allocations from the reserved chunk if available */
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@ -967,12 +967,9 @@ restart:
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if (is_atomic)
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goto fail;
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mutex_lock(&pcpu_alloc_mutex);
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if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
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chunk = pcpu_create_chunk();
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if (!chunk) {
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mutex_unlock(&pcpu_alloc_mutex);
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err = "failed to allocate new chunk";
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goto fail;
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}
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@ -983,7 +980,6 @@ restart:
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spin_lock_irqsave(&pcpu_lock, flags);
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}
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mutex_unlock(&pcpu_alloc_mutex);
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goto restart;
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area_found:
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@ -993,8 +989,6 @@ area_found:
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if (!is_atomic) {
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int page_start, page_end, rs, re;
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mutex_lock(&pcpu_alloc_mutex);
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page_start = PFN_DOWN(off);
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page_end = PFN_UP(off + size);
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@ -1005,7 +999,6 @@ area_found:
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spin_lock_irqsave(&pcpu_lock, flags);
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if (ret) {
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mutex_unlock(&pcpu_alloc_mutex);
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pcpu_free_area(chunk, off, &occ_pages);
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err = "failed to populate";
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goto fail_unlock;
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@ -1045,6 +1038,8 @@ fail:
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/* see the flag handling in pcpu_blance_workfn() */
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pcpu_atomic_alloc_failed = true;
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pcpu_schedule_balance_work();
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} else {
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mutex_unlock(&pcpu_alloc_mutex);
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}
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return NULL;
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}
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@ -1129,6 +1124,7 @@ static void pcpu_balance_workfn(struct work_struct *work)
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if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
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continue;
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list_del_init(&chunk->map_extend_list);
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list_move(&chunk->list, &to_free);
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}
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@ -1146,6 +1142,25 @@ static void pcpu_balance_workfn(struct work_struct *work)
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pcpu_destroy_chunk(chunk);
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}
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/* service chunks which requested async area map extension */
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do {
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int new_alloc = 0;
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spin_lock_irq(&pcpu_lock);
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chunk = list_first_entry_or_null(&pcpu_map_extend_chunks,
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struct pcpu_chunk, map_extend_list);
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if (chunk) {
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list_del_init(&chunk->map_extend_list);
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new_alloc = pcpu_need_to_extend(chunk, false);
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}
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spin_unlock_irq(&pcpu_lock);
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if (new_alloc)
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pcpu_extend_area_map(chunk, new_alloc);
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} while (chunk);
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/*
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* Ensure there are certain number of free populated pages for
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* atomic allocs. Fill up from the most packed so that atomic
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@ -1644,7 +1659,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
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*/
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schunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);
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INIT_LIST_HEAD(&schunk->list);
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INIT_WORK(&schunk->map_extend_work, pcpu_map_extend_workfn);
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INIT_LIST_HEAD(&schunk->map_extend_list);
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schunk->base_addr = base_addr;
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schunk->map = smap;
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schunk->map_alloc = ARRAY_SIZE(smap);
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@ -1673,7 +1688,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
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if (dyn_size) {
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dchunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);
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INIT_LIST_HEAD(&dchunk->list);
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INIT_WORK(&dchunk->map_extend_work, pcpu_map_extend_workfn);
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INIT_LIST_HEAD(&dchunk->map_extend_list);
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dchunk->base_addr = base_addr;
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dchunk->map = dmap;
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dchunk->map_alloc = ARRAY_SIZE(dmap);
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