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Message-ID: <49D075A3.1050202@cosmosbay.com> Date: Mon, 30 Mar 2009 09:32:51 +0200 From: Eric Dumazet <dada1@...mosbay.com> To: Roman Mindalev <r000n@...0n.net> CC: Stephen Hemminger <shemminger@...tta.com>, Patrick McHardy <kaber@...sh.net>, LKML <linux-kernel@...r.kernel.org>, netfilter@...r.kernel.org Subject: Re: Regression caused by commit "netfilter: iptables: lock free counters" Roman Mindalev a écrit : > Hi. > Since 2.6.29-git1 I got many debug messages in kernel log. > One from them: > > Mar 29 12:06:11 desktop kernel: [ 917.414369] BUG: using > smp_processor_id() in preemptible [00000000] code: hddtemp/2820 Mar 29 > 12:06:11 desktop kernel: [ 917.414378] caller is > ipt_do_table+0xd0/0x3a8 [ip_tables] Mar 29 12:06:11 desktop kernel: > [ 917.414382] Pid: 2820, comm: hddtemp Not tainted > 2.6.29-05093-gc31f403 #1 Mar 29 12:06:11 desktop kernel: [ 917.414386] > Call Trace: Mar 29 12:06:11 desktop kernel: [ 917.414393] > [<ffffffff8042d037>] debug_smp_processor_id+0xe7/0xf0 Mar 29 12:06:11 > desktop kernel: [ 917.414400] [<ffffffffa0171f10>] > ipt_do_table+0xd0/0x3a8 [ip_tables] Mar 29 12:06:11 desktop kernel: > [ 917.414414] [<ffffffffa0180d0e>] ? nf_conntrack_in+0x23e/0x610 > [nf_conntrack] Mar 29 12:06:11 desktop kernel: [ 917.414422] > [<ffffffff8026d47d>] ? trace_hardirqs_off+0xd/0x10 Mar 29 12:06:11 > desktop kernel: [ 917.414429] [<ffffffffa008e0b3>] > ipt_local_out_hook+0x53/0x60 [iptable_filter] Mar 29 12:06:11 desktop > kernel: [ 917.414435] [<ffffffff80546a07>] nf_iterate+0x67/0xa0 Mar > 29 12:06:11 desktop kernel: [ 917.414441] [<ffffffff80551140>] ? > dst_output+0x0/0x10 Mar 29 12:06:11 desktop kernel: [ 917.414446] > [<ffffffff80546af5>] nf_hook_slow+0xb5/0x100 Mar 29 12:06:11 desktop > kernel: [ 917.414452] [<ffffffff80551140>] ? dst_output+0x0/0x10 Mar > 29 12:06:11 desktop kernel: [ 917.414458] [<ffffffff80552f7f>] > __ip_local_out+0x9f/0xb0 Mar 29 12:06:11 desktop kernel: > [ 917.414464] [<ffffffff8058c4db>] ? bictcp_cong_avoid+0x4b/0x2d0 Mar > 29 12:06:11 desktop kernel: [ 917.414469] [<ffffffff80552fa1>] > ip_local_out+0x11/0x30 Mar 29 12:06:11 desktop kernel: [ 917.414474] > [<ffffffff8055389c>] ip_queue_xmit+0x21c/0x410 Mar 29 12:06:11 desktop > kernel: [ 917.414480] [<ffffffff80272825>] ? > print_lock_contention_bug+0x25/0x120 Mar 29 12:06:11 desktop kernel: > [ 917.414486] [<ffffffff8056810e>] ? > tcp_established_options+0x3e/0xe0 Mar 29 12:06:11 desktop kernel: > [ 917.414492] [<ffffffff80272825>] ? > print_lock_contention_bug+0x25/0x120 Mar 29 12:06:11 desktop kernel: > [ 917.414498] [<ffffffff80568ef5>] tcp_transmit_skb+0x535/0x820 Mar > 29 12:06:11 desktop kernel: [ 917.414504] [<ffffffff8056b5fb>] > tcp_write_xmit+0x20b/0xaa0 Mar 29 12:06:11 desktop kernel: > [ 917.414510] [<ffffffff8055d451>] ? sk_stream_alloc_skb+0x41/0x110 > Mar 29 12:06:11 desktop kernel: [ 917.414515] [<ffffffff8052799e>] ? > __alloc_skb+0x6e/0x150 Mar 29 12:06:11 desktop kernel: [ 917.414521] > [<ffffffff8056befb>] __tcp_push_pending_frames+0x2b/0x90 Mar 29 > 12:06:11 desktop kernel: [ 917.414527] [<ffffffff8055ddc3>] > tcp_sendmsg+0x8a3/0xbb0 Mar 29 12:06:11 desktop kernel: [ 917.414533] > [<ffffffff8051d2bb>] sock_aio_write+0x12b/0x140 Mar 29 12:06:11 desktop > kernel: [ 917.414539] [<ffffffff802df6f1>] do_sync_write+0xf1/0x140 > Mar 29 12:06:11 desktop kernel: [ 917.414545] [<ffffffff8025e470>] ? > autoremove_wake_function+0x0/0x40 Mar 29 12:06:11 desktop kernel: > [ 917.414551] [<ffffffff802e0259>] vfs_write+0x179/0x190 Mar 29 > 12:06:11 desktop kernel: [ 917.414557] [<ffffffff802e0360>] > sys_write+0x50/0x90 Mar 29 12:06:11 desktop kernel: [ 917.414563] > [<ffffffff8020b51b>] system_call_fastpath+0x16/0x1b > > Result of the bisection: > > 784544739a25c30637397ace5489eeb6e15d7d49 is first bad commit > commit 784544739a25c30637397ace5489eeb6e15d7d49 > Author: Stephen Hemminger <shemminger@...tta.com> > Date: Fri Feb 20 10:35:32 2009 +0100 > > netfilter: iptables: lock free counters > > The reader/writer lock in ip_tables is acquired in the critical > path of processing packets and is one of the reasons just loading > iptables can cause a 20% performance loss. The rwlock serves two > functions: > > 1) it prevents changes to table state (xt_replace) while table is > in use. This is now handled by doing rcu on the xt_table. When > table is replaced, the new table(s) are put in and the old one > table(s) are freed after RCU period. > > 2) it provides synchronization when accesing the counter values. > This is now handled by swapping in new table_info entries for > each cpu then summing the old values, and putting the result back > onto one cpu. On a busy system it may cause sampling to occur at > different times on each cpu, but no packet/byte counts are lost in > the process. > > Signed-off-by: Stephen Hemminger <shemminger@...tta.com> > > Sucessfully tested on my dual quad core machine too, but iptables > only (no ipv6 here) BTW, my new "tbench 8" result is 2450 MB/s, (it > was 2150 MB/s not so long ago) > > Acked-by: Eric Dumazet <dada1@...mosbay.com> > Signed-off-by: Patrick McHardy <kaber@...sh.net> > > :040000 040000 67ef5761d009330e8d538dd1a3aff77c86995172 > 0d8d6398ced2117bb6995b0c414fd8013685324e M include :040000 040000 > 0317c745a0722ade9a6c0cbe9d6cb92abbd40efa > 0eb195a365164c05e7c764ab1c2a7da891276837 M net > > After reverting commit no more these messages. > > This issue in bugzilla: http://bugzilla.kernel.org/show_bug.cgi?id=12960 Thanks Roman for this excellent report Could you try following patch ? [PATCH] netfilter: use rcu_read_bh() in ipt_do_table() Commit 784544739a25c30637397ace5489eeb6e15d7d49 (netfilter: iptables: lock free counters) forgot to disable BH in arpt_do_table(), ipt_do_table() and ip6t_do_table() Use rcu_read_lock_bh() instead of rcu_read_lock() cures the problem. Reported-and-bisected-by: Roman Mindalev <r000n@...0n.net> Signed-off-by: Eric Dumazet <dada1@...mosbay.com> --- diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 35c5f6a..5ba533d 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -253,7 +253,7 @@ unsigned int arpt_do_table(struct sk_buff *skb, indev = in ? in->name : nulldevname; outdev = out ? out->name : nulldevname; - rcu_read_lock(); + rcu_read_lock_bh(); private = rcu_dereference(table->private); table_base = rcu_dereference(private->entries[smp_processor_id()]); @@ -329,7 +329,7 @@ unsigned int arpt_do_table(struct sk_buff *skb, } } while (!hotdrop); - rcu_read_unlock(); + rcu_read_unlock_bh(); if (hotdrop) return NF_DROP; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 82ee7c9..810c0b6 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -339,7 +339,7 @@ ipt_do_table(struct sk_buff *skb, IP_NF_ASSERT(table->valid_hooks & (1 << hook)); - rcu_read_lock(); + rcu_read_lock_bh(); private = rcu_dereference(table->private); table_base = rcu_dereference(private->entries[smp_processor_id()]); @@ -437,7 +437,7 @@ ipt_do_table(struct sk_buff *skb, } } while (!hotdrop); - rcu_read_unlock(); + rcu_read_unlock_bh(); #ifdef DEBUG_ALLOW_ALL return NF_ACCEPT; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index e89cfa3..dfed176 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -365,7 +365,7 @@ ip6t_do_table(struct sk_buff *skb, IP_NF_ASSERT(table->valid_hooks & (1 << hook)); - rcu_read_lock(); + rcu_read_lock_bh(); private = rcu_dereference(table->private); table_base = rcu_dereference(private->entries[smp_processor_id()]); @@ -466,7 +466,7 @@ ip6t_do_table(struct sk_buff *skb, #ifdef CONFIG_NETFILTER_DEBUG ((struct ip6t_entry *)table_base)->comefrom = NETFILTER_LINK_POISON; #endif - rcu_read_unlock(); + rcu_read_unlock_bh(); #ifdef DEBUG_ALLOW_ALL return NF_ACCEPT; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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