Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:33542 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762064Ab2EQOv3 (ORCPT ); Thu, 17 May 2012 10:51:29 -0400 From: Mel Gorman To: Andrew Morton Cc: Linux-MM , Linux-Netdev , Linux-NFS , LKML , David Miller , Trond Myklebust , Neil Brown , Christoph Hellwig , Peter Zijlstra , Mike Christie , Eric B Munson , Mel Gorman Subject: [PATCH 01/12] netvm: Prevent a stream-specific deadlock Date: Thu, 17 May 2012 15:51:14 +0100 Message-Id: <1337266285-8102-2-git-send-email-mgorman@suse.de> In-Reply-To: <1337266285-8102-1-git-send-email-mgorman@suse.de> References: <1337266285-8102-1-git-send-email-mgorman@suse.de> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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 --- 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 7cb714c..eb0dd76 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1280,12 +1280,13 @@ static inline int sk_wmem_schedule(struct sock *sk, int size) __sk_mem_schedule(sk, size, SK_MEM_SEND); } -static inline int sk_rmem_schedule(struct sock *sk, int size) +static inline int sk_rmem_schedule(struct sock *sk, struct sk_buff *skb) { if (!sk_has_account(sk)) return 1; - 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 5016fa5..aaf711c 100644 --- a/net/caif/caif_socket.c +++ b/net/caif/caif_socket.c @@ -142,7 +142,7 @@ 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); if (net_ratelimit()) pr_debug("sending flow OFF due to rmem_schedule\n"); diff --git a/net/core/sock.c b/net/core/sock.c index 906f6f4..e3dea27 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -289,6 +289,18 @@ 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); @@ -391,7 +403,7 @@ 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 257b617..b1c787c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4434,19 +4434,19 @@ static void tcp_ofo_queue(struct sock *sk) static int tcp_prune_ofo_queue(struct sock *sk); static int tcp_prune_queue(struct sock *sk); -static inline int tcp_try_rmem_schedule(struct sock *sk, unsigned int size) +static inline 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; } } @@ -4461,7 +4461,7 @@ 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; @@ -4630,7 +4630,7 @@ 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; skb_set_owner_r(skb, sk); 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; } -- 1.7.9.2