When queueing a set element add or removal operation to the transaction log, check if the previous operation already asks for a the identical operation on the same set. If so, store the element reference in the preceding operation. This significantlty reduces memory consumption when many set add/delete operations appear in a single transaction. Example: 10k elements require 937kb of memory (10k allocations from kmalloc-96 slab). Assuming we can compact 4 elements in the same set, 468 kbytes are needed (64 bytes for base struct, nft_trans_elemn, 32 bytes for nft_trans_one_elem structure, so 2500 allocations from kmalloc-192 slab). For large batch updates we can compact up to 62 elements into one single nft_trans_elem structure (~65% mem reduction): (64 bytes for base struct, nft_trans_elem, 32 byte for nft_trans_one_elem struct). We can halve size of nft_trans_one_elem struct by moving timeout/expire/update_flags into a dynamically allocated structure, this allows to store 124 elements in a 2k slab nft_trans_elem struct. This is done in a followup patch. Signed-off-by: Florian Westphal <fw@xxxxxxxxx> --- net/netfilter/nf_tables_api.c | 71 +++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index bdf5ba21c76d..e96e538fe2eb 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -25,6 +25,7 @@ #define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-")) #define NFT_SET_MAX_ANONLEN 16 +#define NFT_MAX_SET_NELEMS ((2048 - sizeof(struct nft_trans_elem)) / sizeof(struct nft_trans_one_elem)) unsigned int nf_tables_net_id __read_mostly; @@ -391,6 +392,69 @@ static void nf_tables_unregister_hook(struct net *net, return __nf_tables_unregister_hook(net, table, chain, false); } +static bool nft_trans_collapse_set_elem_allowed(const struct nft_trans_elem *a, const struct nft_trans_elem *b) +{ + return a->set == b->set && a->bound == b->bound && a->nelems < NFT_MAX_SET_NELEMS; +} + +static bool nft_trans_collapse_set_elem(struct nftables_pernet *nft_net, + struct nft_trans_elem *tail, + struct nft_trans_elem *trans, + gfp_t gfp) +{ + unsigned int nelems, old_nelems = tail->nelems; + struct nft_trans_elem *new_trans; + + if (!nft_trans_collapse_set_elem_allowed(tail, trans)) + return false; + + if (WARN_ON_ONCE(trans->nelems != 1)) + return false; + + if (check_add_overflow(old_nelems, trans->nelems, &nelems)) + return false; + + /* krealloc might free tail which invalidates list pointers */ + list_del_init(&tail->nft_trans.list); + + new_trans = krealloc(tail, struct_size(tail, elems, nelems), gfp); + if (!new_trans) { + list_add_tail(&tail->nft_trans.list, &nft_net->commit_list); + return false; + } + + INIT_LIST_HEAD(&new_trans->nft_trans.list); + new_trans->nelems = nelems; + new_trans->elems[old_nelems] = trans->elems[0]; + list_add_tail(&new_trans->nft_trans.list, &nft_net->commit_list); + + return true; +} + +static bool nft_trans_try_collapse(struct nftables_pernet *nft_net, + struct nft_trans *trans, gfp_t gfp) +{ + struct nft_trans *tail; + + if (list_empty(&nft_net->commit_list)) + return false; + + tail = list_last_entry(&nft_net->commit_list, struct nft_trans, list); + + if (tail->msg_type != trans->msg_type) + return false; + + switch (trans->msg_type) { + case NFT_MSG_NEWSETELEM: + case NFT_MSG_DELSETELEM: + return nft_trans_collapse_set_elem(nft_net, + nft_trans_container_elem(tail), + nft_trans_container_elem(trans), gfp); + } + + return false; +} + static void nft_trans_commit_list_add_tail(struct net *net, struct nft_trans *trans) { struct nftables_pernet *nft_net = nft_pernet(net); @@ -424,11 +488,18 @@ static void nft_trans_commit_list_add_tail(struct net *net, struct nft_trans *tr static void nft_trans_commit_list_add_elem(struct net *net, struct nft_trans *trans, gfp_t gfp) { + struct nftables_pernet *nft_net = nft_pernet(net); + WARN_ON_ONCE(trans->msg_type != NFT_MSG_NEWSETELEM && trans->msg_type != NFT_MSG_DELSETELEM); might_alloc(gfp); + if (nft_trans_try_collapse(nft_net, trans, gfp)) { + kfree(trans); + return; + } + nft_trans_commit_list_add_tail(net, trans); } -- 2.45.2