From patchwork Wed Jun 20 09:35:20 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mel Gorman X-Patchwork-Id: 165936 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 1EBC7B6FD5 for ; Wed, 20 Jun 2012 19:38:14 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756016Ab2FTJfn (ORCPT ); Wed, 20 Jun 2012 05:35:43 -0400 Received: from cantor2.suse.de ([195.135.220.15]:58717 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755997Ab2FTJfk (ORCPT ); Wed, 20 Jun 2012 05:35:40 -0400 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id 65AC4A39CE; Wed, 20 Jun 2012 11:35:39 +0200 (CEST) From: Mel Gorman To: Andrew Morton Cc: Linux-MM , Linux-Netdev , LKML , David Miller , Neil Brown , Peter Zijlstra , Mike Christie , Eric B Munson , Mel Gorman Subject: [PATCH 17/17] netvm: Prevent a stream-specific deadlock Date: Wed, 20 Jun 2012 10:35:20 +0100 Message-Id: <1340184920-22288-18-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.7.9.2 In-Reply-To: <1340184920-22288-1-git-send-email-mgorman@suse.de> References: <1340184920-22288-1-git-send-email-mgorman@suse.de> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org It could happen that all !SOCK_MEMALLOC sockets have buffered so much data that we're over the global rmem limit. This will prevent SOCK_MEMALLOC buffers from receiving data, which will prevent userspace from running, which is needed to reduce the buffered data. Fix this by exempting the SOCK_MEMALLOC sockets from the rmem limit. Once this change it applied, it is important that sockets that set SOCK_MEMALLOC do not clear the flag until the socket is being torn down. If this happens, a warning is generated and the tokens reclaimed to avoid accounting errors until the bug is fixed. [davem@davemloft.net: Warning about clearing SOCK_MEMALLOC] Signed-off-by: Peter Zijlstra Signed-off-by: Mel Gorman Acked-by: David S. Miller --- include/net/sock.h | 7 ++++--- net/caif/caif_socket.c | 2 +- net/core/sock.c | 14 +++++++++++++- net/ipv4/tcp_input.c | 12 ++++++------ net/sctp/ulpevent.c | 2 +- 5 files changed, 25 insertions(+), 12 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 772577f..9ab9934 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1315,12 +1315,13 @@ static inline bool sk_wmem_schedule(struct sock *sk, int size) __sk_mem_schedule(sk, size, SK_MEM_SEND); } -static inline bool sk_rmem_schedule(struct sock *sk, int size) +static inline bool sk_rmem_schedule(struct sock *sk, struct sk_buff *skb) { if (!sk_has_account(sk)) return true; - return size <= sk->sk_forward_alloc || - __sk_mem_schedule(sk, size, SK_MEM_RECV); + return skb->truesize <= sk->sk_forward_alloc || + __sk_mem_schedule(sk, skb->truesize, SK_MEM_RECV) || + skb_pfmemalloc(skb); } static inline void sk_mem_reclaim(struct sock *sk) diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c index fb89443..5855b3a 100644 --- a/net/caif/caif_socket.c +++ b/net/caif/caif_socket.c @@ -141,7 +141,7 @@ static int caif_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) err = sk_filter(sk, skb); if (err) return err; - if (!sk_rmem_schedule(sk, skb->truesize) && rx_flow_is_on(cf_sk)) { + if (!sk_rmem_schedule(sk, skb) && rx_flow_is_on(cf_sk)) { set_rx_flow_off(cf_sk); net_dbg_ratelimited("sending flow OFF due to rmem_schedule\n"); caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_OFF_REQ); diff --git a/net/core/sock.c b/net/core/sock.c index 4388a8a..b51a49a 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -294,6 +294,18 @@ void sk_clear_memalloc(struct sock *sk) sock_reset_flag(sk, SOCK_MEMALLOC); sk->sk_allocation &= ~__GFP_MEMALLOC; static_key_slow_dec(&memalloc_socks); + + /* + * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward + * progress of swapping. However, if SOCK_MEMALLOC is cleared while + * it has rmem allocations there is a risk that the user of the + * socket cannot make forward progress due to exceeding the rmem + * limits. By rights, sk_clear_memalloc() should only be called + * on sockets being torn down but warn and reset the accounting if + * that assumption breaks. + */ + if (WARN_ON(sk->sk_forward_alloc)) + sk_mem_reclaim(sk); } EXPORT_SYMBOL_GPL(sk_clear_memalloc); @@ -395,7 +407,7 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) if (err) return err; - if (!sk_rmem_schedule(sk, skb->truesize)) { + if (!sk_rmem_schedule(sk, skb)) { atomic_inc(&sk->sk_drops); return -ENOBUFS; } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b224eb8..c121d6a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4512,19 +4512,19 @@ static void tcp_ofo_queue(struct sock *sk) static bool tcp_prune_ofo_queue(struct sock *sk); static int tcp_prune_queue(struct sock *sk); -static int tcp_try_rmem_schedule(struct sock *sk, unsigned int size) +static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb) { if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf || - !sk_rmem_schedule(sk, size)) { + !sk_rmem_schedule(sk, skb)) { if (tcp_prune_queue(sk) < 0) return -1; - if (!sk_rmem_schedule(sk, size)) { + if (!sk_rmem_schedule(sk, skb)) { if (!tcp_prune_ofo_queue(sk)) return -1; - if (!sk_rmem_schedule(sk, size)) + if (!sk_rmem_schedule(sk, skb)) return -1; } } @@ -4579,7 +4579,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) TCP_ECN_check_ce(tp, skb); - if (tcp_try_rmem_schedule(sk, skb->truesize)) { + if (tcp_try_rmem_schedule(sk, skb)) { /* TODO: should increment a counter */ __kfree_skb(skb); return; @@ -4791,7 +4791,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) if (eaten <= 0) { queue_and_out: if (eaten < 0 && - tcp_try_rmem_schedule(sk, skb->truesize)) + tcp_try_rmem_schedule(sk, skb)) goto drop; eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen); diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c index 8a84017..6c6ed2d 100644 --- a/net/sctp/ulpevent.c +++ b/net/sctp/ulpevent.c @@ -702,7 +702,7 @@ struct sctp_ulpevent *sctp_ulpevent_make_rcvmsg(struct sctp_association *asoc, if (rx_count >= asoc->base.sk->sk_rcvbuf) { if ((asoc->base.sk->sk_userlocks & SOCK_RCVBUF_LOCK) || - (!sk_rmem_schedule(asoc->base.sk, chunk->skb->truesize))) + (!sk_rmem_schedule(asoc->base.sk, chunk->skb))) goto fail; }