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Date: Wed, 11 May 2011 10:49:01 -0400 From: TB <lkml@...hboom.com> To: Stephen Hemminger <shemminger@...tta.com> CC: "Brandeburg, Jesse" <jesse.brandeburg@...el.com>, David Miller <davem@...emloft.net>, Sangtae Ha <sangtae.ha@...il.com>, Injong Rhee <injongrhee@...il.com>, "Valdis.Kletnieks@...edu" <Valdis.Kletnieks@...edu>, "rdunlap@...otime.net" <rdunlap@...otime.net>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error On 11-05-06 12:53 PM, Stephen Hemminger wrote: > On Fri, 06 May 2011 12:15:46 -0400 > TB <lkml@...hboom.com> wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> On 11-05-04 04:53 PM, Brandeburg, Jesse wrote: >>> >>> >>> On Wed, 4 May 2011, Stephen Hemminger wrote: >>> >>>> TCP Cubic keeps a metric that estimates the amount of delayed >>>> acknowledgements to use in adjusting the window. If an abnormally >>>> large number of packets are acknowledged at once, then the update >>>> could wrap and reach zero. This kind of ACK could only >>>> happen when there was a large window and huge number of >>>> ACK's were lost. >>>> >>>> This patch limits the value of delayed ack ratio. The choice of 32 >>>> is just a conservative value since normally it should be range of >>>> 1 to 4 packets. >>>> >>>> Signed-off-by: Stephen Hemminger <shemminger@...tta.com> >>> >>> patch seems fine, but please credit the reporter (lkml@...hboom.com) with >>> reporting the issue with logs, maybe even with Reported-by: and some kind >>> of reference to the panic message or the email thread in the text or >>> header? >> >> We're currently testing the patch on 6 production servers > > Thank you, is there some regularity to the failures previously? This is now being tested on about 50 servers and we just had another panic, on a server with 2.6.38.5 and this patch. [405542.454073] ------------[ cut here ]------------ [405542.454109] kernel BUG at net/ipv4/tcp_output.c:1006! [405542.454136] invalid opcode: 0000 [#1] [405542.454166] last sysfs file: /sys/devices/pci0000:00/0000:00:1f.2/host6/scsi_host/host6/proc_name [405542.454213] CPU 0 [405542.454220] Modules linked in: i2c_i801 evdev i2c_core button [last unloaded: scsi_wait_scan] [405542.454300] [405542.454320] Pid: 0, comm: swapper Not tainted 2.6.38.5 #8 / [405542.454379] RIP: 0010:[<ffffffff814e7ed2>] [<ffffffff814e7ed2>] tcp_fragment+0x22/0x29a [405542.454433] RSP: 0018:ffff8800bf403a30 EFLAGS: 00010202 [405542.454460] RAX: ffff88000cd35000 RBX: ffff88006b84f480 RCX: 0000000000000218 [405542.454504] RDX: 0000000000001708 RSI: ffff88006b84f480 RDI: ffff880008d6b200 [405542.454548] RBP: 0000000000001540 R08: 0000000000000002 R09: 000000001027984a [405542.454592] R10: ffff8800b915f428 R11: ffff880008d6b200 R12: ffff88006b84f4a8 [405542.454636] R13: 0000000000001708 R14: 0000000000000000 R15: ffff880008d6b200 [405542.454680] FS: 0000000000000000(0000) GS:ffff8800bf400000(0000) knlGS:0000000000000000 [405542.454726] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [405542.454754] CR2: 00007f94055c7000 CR3: 000000083e0bd000 CR4: 00000000000006f0 [405542.454798] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [405542.454842] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [405542.454886] Process swapper (pid: 0, threadinfo ffffffff8176c000, task ffffffff81777020) [405542.454931] Stack: [405542.454951] 0000000000000000 0000021808d6b798 00000002000005b4 ffff88006b84f480 [405542.455006] ffff880008d6b200 ffff88006b84f4a8 0000000000000015 0000000000000000 [405542.455061] ffff880008d6b300 ffffffff814df7a4 ffff8802a3965140 00000000000001a0 [405542.455115] Call Trace: [405542.455137] <IRQ> [405542.455162] [<ffffffff814df7a4>] ? tcp_mark_head_lost+0x13c/0x202 [405542.455192] [<ffffffff814e33a8>] ? tcp_ack+0xe98/0x1a89 [405542.455220] [<ffffffff814e42ca>] ? tcp_validate_incoming+0x69/0x290 [405542.455250] [<ffffffff814e4c9b>] ? tcp_rcv_established+0x7aa/0xa13 [405542.455281] [<ffffffff814ec60b>] ? tcp_v4_do_rcv+0x1b2/0x382 [405542.455310] [<ffffffff814c95d4>] ? nf_iterate+0x40/0x78 [405542.455338] [<ffffffff814ecc5f>] ? tcp_v4_rcv+0x484/0x797 [405542.455368] [<ffffffff814d11c7>] ? ip_local_deliver_finish+0xab/0x139 [405542.455398] [<ffffffff814ae2b3>] ? __netif_receive_skb+0x31c/0x349 [405542.455428] [<ffffffff814aec82>] ? netif_receive_skb+0x67/0x6d [405542.455457] [<ffffffff814af1fb>] ? napi_gro_receive+0x9d/0xab [405542.455485] [<ffffffff814aed57>] ? napi_skb_finish+0x1c/0x31 [405542.455516] [<ffffffff813e4248>] ? igb_poll+0x7d5/0xb2e [405542.455544] [<ffffffff813e432f>] ? igb_poll+0x8bc/0xb2e [405542.455572] [<ffffffff813e211a>] ? igb_msix_ring+0x6e/0x75 [405542.455602] [<ffffffff8106749c>] ? handle_IRQ_event+0x51/0x119 [405542.455631] [<ffffffff814af337>] ? net_rx_action+0xa7/0x212 [405542.455661] [<ffffffff8103b6c2>] ? __do_softirq+0xbe/0x184 [405542.455690] [<ffffffff8100364c>] ? call_softirq+0x1c/0x28 [405542.455719] [<ffffffff81005085>] ? do_softirq+0x31/0x63 [405542.455746] [<ffffffff8103b56c>] ? irq_exit+0x36/0x78 [405542.455773] [<ffffffff81004784>] ? do_IRQ+0x98/0xae [405542.455802] [<ffffffff81562ed3>] ? ret_from_intr+0x0/0xe [405542.455829] <EOI> [405542.455860] [<ffffffff81009a41>] ? mwait_idle+0xb9/0xf3 [405542.455888] [<ffffffff81001c6e>] ? cpu_idle+0x57/0x8d [405542.455921] [<ffffffff81801c49>] ? start_kernel+0x34e/0x35a [405542.455950] [<ffffffff81801398>] ? x86_64_start_kernel+0xf3/0xf9 [405542.455977] Code: f> [405542.456239] RIP [<ffffffff814e7ed2>] tcp_fragment+0x22/0x29a [405542.456270] RSP <ffff8800bf403a30> [405542.456543] ---[ end trace 231aaa222f893065 ]--- [405542.456600] Kernel panic - not syncing: Fatal exception in interrupt [405542.456659] Pid: 0, comm: swapper Tainted: G D 2.6.38.5 #8 [405542.456719] Call Trace: [405542.456770] <IRQ> [<ffffffff81560960>] ? panic+0x9d/0x1a0 [405542.456863] [<ffffffff81562ed3>] ? ret_from_intr+0x0/0xe [405542.456923] [<ffffffff810365bb>] ? kmsg_dump+0x46/0xec [405542.456981] [<ffffffff81006176>] ? oops_end+0x9f/0xac [405542.457039] [<ffffffff81003f83>] ? do_invalid_op+0x85/0x8f [405542.457097] [<ffffffff814e7ed2>] ? tcp_fragment+0x22/0x29a [405542.457156] [<ffffffff814e80a9>] ? tcp_fragment+0x1f9/0x29a [405542.457216] [<ffffffff810033d5>] ? invalid_op+0x15/0x20 [405542.457276] [<ffffffff814e7ed2>] ? tcp_fragment+0x22/0x29a [405542.457337] [<ffffffff814df7a4>] ? tcp_mark_head_lost+0x13c/0x202 [405542.457400] [<ffffffff814e33a8>] ? tcp_ack+0xe98/0x1a89 [405542.457461] [<ffffffff814e42ca>] ? tcp_validate_incoming+0x69/0x290 [405542.457524] [<ffffffff814e4c9b>] ? tcp_rcv_established+0x7aa/0xa13 [405542.457586] [<ffffffff814ec60b>] ? tcp_v4_do_rcv+0x1b2/0x382 [405542.457645] [<ffffffff814c95d4>] ? nf_iterate+0x40/0x78 [405542.457703] [<ffffffff814ecc5f>] ? tcp_v4_rcv+0x484/0x797 [405542.457761] [<ffffffff814d11c7>] ? ip_local_deliver_finish+0xab/0x139 [405542.457827] [<ffffffff814ae2b3>] ? __netif_receive_skb+0x31c/0x349 [405542.457894] [<ffffffff814aec82>] ? netif_receive_skb+0x67/0x6d [405542.457953] [<ffffffff814af1fb>] ? napi_gro_receive+0x9d/0xab [405542.458021] [<ffffffff814aed57>] ? napi_skb_finish+0x1c/0x31 [405542.458080] [<ffffffff813e4248>] ? igb_poll+0x7d5/0xb2e [405542.458138] [<ffffffff813e432f>] ? igb_poll+0x8bc/0xb2e [405542.458196] [<ffffffff813e211a>] ? igb_msix_ring+0x6e/0x75 [405542.458254] [<ffffffff8106749c>] ? handle_IRQ_event+0x51/0x119 [405542.458313] [<ffffffff814af337>] ? net_rx_action+0xa7/0x212 [405542.458371] [<ffffffff8103b6c2>] ? __do_softirq+0xbe/0x184 [405542.458430] [<ffffffff8100364c>] ? call_softirq+0x1c/0x28 [405542.458488] [<ffffffff81005085>] ? do_softirq+0x31/0x63 [405542.458545] [<ffffffff8103b56c>] ? irq_exit+0x36/0x78 [405542.458602] [<ffffffff81004784>] ? do_IRQ+0x98/0xae [405542.458660] [<ffffffff81562ed3>] ? ret_from_intr+0x0/0xe [405542.458717] <EOI> [<ffffffff81009a41>] ? mwait_idle+0xb9/0xf3 [405542.458810] [<ffffffff81001c6e>] ? cpu_idle+0x57/0x8d [405542.458867] [<ffffffff81801c49>] ? start_kernel+0x34e/0x35a [405542.458926] [<ffffffff81801398>] ? x86_64_start_kernel+0xf3/0xf9 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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