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kvfree_rcu: Directly allocate page for single-argument case
Single-argument kvfree_rcu() must be invoked from sleepable contexts, so we can directly allocate pages. Furthermmore, the fallback in case of page-allocation failure is the high-latency synchronize_rcu(), so it makes sense to do these page allocations from the fastpath, and even to permit limited sleeping within the allocator. This commit therefore allocates if needed on the fastpath using GFP_KERNEL|__GFP_RETRY_MAYFAIL. This also has the beneficial effect of leaving kvfree_rcu()'s per-CPU caches to the double-argument variant of kvfree_rcu(), given that the double-argument variant cannot directly invoke the allocator. [ paulmck: Add add_ptr_to_bulk_krc_lock header comment per Michal Hocko. ] Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
parent
a38fd87484
commit
148e3731d1
1 changed files with 26 additions and 16 deletions
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@ -3493,37 +3493,50 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp)
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}
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}
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// Record ptr in a page managed by krcp, with the pre-krc_this_cpu_lock()
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// state specified by flags. If can_alloc is true, the caller must
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// be schedulable and not be holding any locks or mutexes that might be
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// acquired by the memory allocator or anything that it might invoke.
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// Returns true if ptr was successfully recorded, else the caller must
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// use a fallback.
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static inline bool
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kvfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp, void *ptr)
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add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
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unsigned long *flags, void *ptr, bool can_alloc)
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{
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struct kvfree_rcu_bulk_data *bnode;
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int idx;
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if (unlikely(!krcp->initialized))
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*krcp = krc_this_cpu_lock(flags);
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if (unlikely(!(*krcp)->initialized))
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return false;
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lockdep_assert_held(&krcp->lock);
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idx = !!is_vmalloc_addr(ptr);
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/* Check if a new block is required. */
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if (!krcp->bkvhead[idx] ||
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krcp->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
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bnode = get_cached_bnode(krcp);
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/* Switch to emergency path. */
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if (!(*krcp)->bkvhead[idx] ||
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(*krcp)->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
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bnode = get_cached_bnode(*krcp);
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if (!bnode && can_alloc) {
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krc_this_cpu_unlock(*krcp, *flags);
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bnode = (struct kvfree_rcu_bulk_data *)
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__get_free_page(GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
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*krcp = krc_this_cpu_lock(flags);
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}
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if (!bnode)
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return false;
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/* Initialize the new block. */
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bnode->nr_records = 0;
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bnode->next = krcp->bkvhead[idx];
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bnode->next = (*krcp)->bkvhead[idx];
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/* Attach it to the head. */
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krcp->bkvhead[idx] = bnode;
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(*krcp)->bkvhead[idx] = bnode;
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}
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/* Finally insert. */
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krcp->bkvhead[idx]->records
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[krcp->bkvhead[idx]->nr_records++] = ptr;
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(*krcp)->bkvhead[idx]->records
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[(*krcp)->bkvhead[idx]->nr_records++] = ptr;
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return true;
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}
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@ -3561,8 +3574,6 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
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ptr = (unsigned long *) func;
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}
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krcp = krc_this_cpu_lock(&flags);
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// Queue the object but don't yet schedule the batch.
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if (debug_rcu_head_queue(ptr)) {
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// Probable double kfree_rcu(), just leak.
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@ -3570,12 +3581,11 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
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__func__, head);
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// Mark as success and leave.
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success = true;
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goto unlock_return;
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return;
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}
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kasan_record_aux_stack(ptr);
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success = kvfree_call_rcu_add_ptr_to_bulk(krcp, ptr);
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success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
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if (!success) {
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run_page_cache_worker(krcp);
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