Date:	Fri, 26 Jun 2009 10:24:58 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dhananjay.phadke@...gic.com
Cc:	akpm@...ux-foundation.org, bugme-daemon@...zilla.kernel.org,
	netdev@...r.kernel.org, bugzilla-daemon@...zilla.kernel.org,
	amit.salecha@...gic.com, herbert@...dor.apana.org.au
Subject: Re: [Bugme-new] [Bug 13617] New: GRO:__napi_complete from
 net_rx_action crash

From: Dhananjay Phadke <dhananjay.phadke@...gic.com>
Date: Fri, 26 Jun 2009 10:13:59 -0700

> mea culpa, likely driver can wait more for rx to drain
> so that we race with napi disable.
> 
> Although, I have question for Dave. If napi code is
> anyway forcing napi completion, should it not flush
> gro flows also? This code predates GRO.

I think there are some reasons, but Herbert Xu is more likely
to remember than I am, CC:'d :-)

> Andrew Morton wrote:
>> 
>> (switched to email.  Please respond via emailed reply-to-all, not via the
>> bugzilla web interface).
>> 
>> 
>> netdev core crashed.  The netxen driver may be implicated.
>> 
>> 
>> Why did amit@...xen.com create this bug report?  Isn't Dhananjay
>> sitting in the next cube?  Perhaps you believe that the driver is OK
>> and that the bug lies in the netdev core?
>> 
>> 
>> 
>> On Thu, 25 Jun 2009 06:55:14 GMT
>> bugzilla-daemon@...zilla.kernel.org wrote:
>> 
>>> http://bugzilla.kernel.org/show_bug.cgi?id=13617
>>>
>>>            Summary: GRO:__napi_complete from net_rx_action crash
>>>            Product: Drivers
>>>            Version: 2.5
>>>           Platform: All
>>>         OS/Version: Linux
>>>               Tree: Mainline
>>>             Status: NEW
>>>           Severity: normal
>>>           Priority: P1
>>>          Component: Network
>>>         AssignedTo: drivers_network@...nel-bugs.osdl.org
>>>         ReportedBy: amit@...xen.com
>>>         Regression: No
>>>
>>>
>>> In net_rx_action, there is check if napi_disable_pending then call
>>> __napi_complete.
>>> In __napi_complete, there is BUG_ON(n->gro_list);
>>> Which has hit in below bug dump.
>>> Why __napi_complete is called from net_rx_action instead of napi_complete.
>>> napi_complete flushes the gro list.
>>>
>>> Below code excerpt from net_rx_action 
>>> http://lxr.linux.no/linux+v2.6.30/net/core/dev.c#L2736
>>>
>>>    if (unlikely(work == weight)) {
>>> 2791       if (unlikely(napi_disable_pending(n)))
>>> 2792              __napi_complete(n);
>>> 2793        else
>>> 2794              list_move_tail(&n->poll_list, list);
>>> 2795   }
>>>
>>> ------------[ cut here ]------------
>>> kernel BUG at net/core/dev.c:2672!
>>> invalid opcode: 0000 [#1] SMP 
>>> last sysfs file: /sys/devices/system/cpu/cpu3/cache/index2/shared_cpu_map
>>> CPU 2 
>>> Modules linked in: netxen_nic nfs lockd nfs_acl auth_rpcgss ipv6 deflate
>>> zlib_deflate ctr twofish twofish_common serpent blowfish des_generic cbc
>>> aes_x86_64 aes_generic xcbc sha256_generic md5 crypto_null af_key autofs4
>>> sunrpc iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi dm_mirror
>>> dm_region_hash dm_log dm_multipath dm_mod video output sbs sbshc pci_slot
>>> battery acpi_memhotplug ac parport ipmi_devintf ide_cd_mod rtc_cmos bnx2 cdrom
>>> serio_raw ipmi_si rtc_core button ipmi_msghandler iTCO_wdt rtc_lib shpchp hpilo
>>> hpwdt i5000_edac pcspkr edac_core ata_piix libata sd_mod scsi_mod cciss ext3
>>> jbd uhci_hcd ohci_hcd ehci_hcd [last unloaded: microcode]
>>> Pid: 0, comm: swapper Tainted: G        W  2.6.30 #1 ProLiant DL380 G5
>>> RIP: 0010:[<ffffffff8043b128>]  [<ffffffff8043b128>] __napi_complete+0x15/0x25
>>> RSP: 0018:ffff880028139eb0  EFLAGS: 00010086
>>> RAX: ffff88023d4056b8 RBX: ffff88023d4056a8 RCX: 0000000002202318
>>> RDX: 00000000001b0000 RSI: ffff880028139d98 RDI: ffff88023d4056a8
>>> RBP: 0000000000000080 R08: 0000000002200000 R09: 000006de15931680
>>> R10: ffffc20011a32318 R11: 0000000000000005 R12: 0000000000000000
>>> R13: ffff8800281440e0 R14: 0000000000000080 R15: 000000000000012c
>>> FS:  0000000000000000(0000) GS:ffff880028136000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
>>> CR2: 00000000008cb530 CR3: 000000023d9ab000 CR4: 00000000000006e0
>>> Jun 23 23:41:27 DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>>> 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>>> Process swapper (pid: 0, threadinfo ffff88023ed28000, task ffff88023ed27570)
>>> Stack:
>>>  ffff88023d4056a8 ffffffff8043ec9f 0000000000000001dut4146 last mes
>>> 000000010004f429
>>>  ffff88023d4056b8sage repeated 6  0000000000000046 0000000000000001
>>> 0000000000000100times
>>> Jun 23 23
>>>  ffffffff8069a098 0000000000000018 000000000000000a:41:32 dut4146 k
>>> ffffffff8023eba6
>>> ernel: BUG: scheCall Trace:
>>> duling while ato <IRQ> <0>mic: swapper/0/0 [<ffffffff8043ec9f>] ?
>>> net_rx_action+0xf0/0x162
>>>  [<ffffffff8023eba6>] ? __do_softirq+0xa3/0x163
>>>  [<ffffffff8020ca7c>] ? call_softirq+0x1c/0x28
>>> x10000100
>>> Jun 2 [<ffffffff8020dc1a>] ? do_softirq+0x2c/0x68
>>>  [<ffffffff8023eac6>] ? irq_exit+0x3f/0x7c
>>>  [<ffffffff8020d46b>] ? do_IRQ+0xa9/0xbf
>>> 3 23:41:32 dut41 [<ffffffff8020c353>] ? ret_from_intr+0x0/0xa
>>>  <EOI> 46 kernel: Modul<0> [<ffffffff80220e41>] ?
>>> hpet_legacy_next_event+0x0/0x7
>>> es linked in: ne [<ffffffff80386e2c>] ? acpi_hw_register_read+0x52/0xe5
>>>  [<ffffffff80394b2a>] ? acpi_idle_enter_simple+0x120/0x14e
>>>  [<ffffffff80394b20>] ? acpi_idle_enter_simple+0x116/0x14e
>>>  [<ffffffff8039486b>] ? acpi_idle_enter_bm+0xd5/0x274
>>>  [<ffffffff8041c020>] ? cpuidle_idle_call+0x7f/0xbb
>>>  [<ffffffff8020aaa5>] ? cpu_idle+0x4a/0x6d
>>> Code: txen_nic nfs loc48 8d kd nfs_acl auth_43 70 48 rpcgss ipv6 defl39 c2 ate
>>> zlib_deflate0f  ctr twofish two18 0e 75 fish_common serpdf ent blowfish des31
>>> c9 41 _generic cbc aes58 5b _x86_64 aes_gene5d 48 89 ric xcbc sha256_c8 c3
>>> generic md5 cryp53 f6 to_null af_key a47 10 01 utofs4 sunrpc is48 89 fb csi_tcp
>>> libiscsi75 04 _tcp libiscsi sc0f 0b eb si_transport_iscfe 48 83 si dm_mirror
>>> dm_7f 50 region_hash dm_l00 74 04 og dm_multipath <0f> dm_mod video out0b eb
>>> put sbs sbshc pcfe e8 i_slot battery a1f cpi_memhotplug a10 f1 ff c parport
>>> ipmi_df0 80 evintf ide_cd_mo63 10 fe d rtc_cmos bnx2 5b c3 cdrom serio_raw 53
>>> 48 89 ipmi_si rtc_corefb e8 
>>>  button ipmi_msgRIP  [<ffffffff8043b128>] __napi_complete+0x15/0x25
>>>  RSP <ffff880028139eb0>
>>> ---[ end trace 9c6b22b26aefd1b1 ]---
>>> handler iTCO_wdtKernel panic - not syncing: Fatal exception in interrupt
>>> Pid: 0, comm: swapper Tainted: G      D W  2.6.30 #1
>>> Call Trace:
>>>  <IRQ>  [<ffffffff8023a3b5>] ? panic+0x86/0x134
>>>  [<ffffffff8020e348>] ? show_registers+0x211/0x21d
>>>  [<ffffffff8024f5ea>] ? up+0xe/0x36
>>>  [<ffffffff8023a9db>] ? release_console_sem+0x174/0x18e
>>>  [<ffffffff804bdd54>] ? oops_end+0xa0/0xad
>>>  [<ffffffff8020cf2c>] ? do_invalid_op+0x85/0x8f
>>>  [<ffffffff8043b128>] ? __napi_complete+0x15/0x25
>>>  [<ffffffffa03ebfe2>] ? netxen_nic_hw_write_wx_2M+0x24/0xa8 [netxen_nic]
>>>  [<ffffffffa03ef866>] ? netxen_process_rcv_ring+0x4eb/0x501 [netxen_nic]
>>>  rtc_lib shpchp  [<ffffffff8020c715>] ? invalid_op+0x15/0x20
>>>  [<ffffffff8043b128>] ? __napi_complete+0x15/0x25
>>>  [<ffffffff8043ec9f>] ? net_rx_action+0xf0/0x162
>>>  [<ffffffff8023eba6>] ? __do_softirq+0xa3/0x163
>>>  [<ffffffff8020ca7c>] ? call_softirq+0x1c/0x28
>>>  [<ffffffff8020dc1a>] ? do_softirq+0x2c/0x68
>>>  [<ffffffff8023eac6>] ? irq_exit+0x3f/0x7c
>>>  [<ffffffff8020d46b>] ? do_IRQ+0xa9/0xbf
>>>  [<ffffffff8020c353>] ? ret_from_intr+0x0/0xa
>>>  <EOI>  [<ffffffff80220e41>] ? hpet_legacy_next_event+0x0/0x7
>>>  [<ffffffff80386e2c>] ? acpi_hw_register_read+0x52/0xe5
>>>  [<ffffffff80394b2a>] ? acpi_idle_enter_simple+0x120/0x14e
>>>  [<ffffffff80394b20>] ? acpi_idle_enter_simple+0x116/0x14e
>>>  [<ffffffff8039486b>] ? acpi_idle_enter_bm+0xd5/0x274
>>>  [<ffffffff8041c020>] ? cpuidle_idle_call+0x7f/0xbb
>>>  [<ffffffff8020aaa5>] ? cpu_idle+0x4a/0x6d
>>>
>>> -- 
>>> Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email
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>> 
>> Checked by AVG - www.avg.com 
>> Version: 8.5.374 / Virus Database: 270.12.91/2201 - Release Date: 06/25/09 17:58:00
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