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SubjectRe: [net] 34fad54c25: kernel BUG at include/linux/skbuff.h:1935!
Date
On Wed, 2016-11-16 at 05:20 +0800, kernel test robot wrote:
> FYI, we noticed the following commit:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> commit 34fad54c2537f7c99d07375e50cb30aa3c23bd83 ("net: __skb_flow_dissect() must cap its return value")
>
> in testcase: pbzip2
> with following parameters:
>
> nr_threads: 25%
> blocksize: 900K
> cpufreq_governor: performance
>
>
>
> on test machine: 48 threads 2 sockets Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz with 64G memory
>
> caused below changes:
>
>
> +------------------------------------------------------------------+------------+------------+
> >
> > | 79774d6bfa | 34fad54c25 |
> +------------------------------------------------------------------+------------+------------+
> >
> > boot_successes | 0 | 2 |
> > boot_failures | 2 | 20 |
> > invoked_oom-killer:gfp_mask=0x | 2 | 2 |
> > Mem-Info | 2 | 2 |
> > Kernel_panic-not_syncing:Out_of_memory_and_no_killable_processes | 2 | 2 |
> > kernel_BUG_at_include/linux/skbuff.h | 0 | 16 |
> > invalid_opcode:#[##]SMP | 0 | 16 |
> > RIP:eth_type_trans | 0 | 16 |
> > Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0 | 15 |
> > calltrace:hub_event | 0 | 1 |
> > WARNING:at_fs/sysfs/dir.c:#sysfs_warn_dup | 0 | 2 |
> > calltrace:parport_pc_init | 0 | 2 |
> > calltrace:SyS_finit_module | 0 | 2 |
> > WARNING:at_lib/kobject.c:#kobject_add_internal | 0 | 2 |
> +------------------------------------------------------------------+------------+------------+
>
>
>
> [ 19.375251] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
> [ 19.388892] Sending DHCP requests .
> [ 19.388892] ------------[ cut here ]------------
> [ 19.388894] kernel BUG at include/linux/skbuff.h:1935!
> [ 19.388895] invalid opcode: 0000 [#1] SMP
> [ 19.388896] Modules linked in:
> [ 19.388897] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.0-rc3-00320-g34fad54 #1
> [ 19.388898] Hardware name: Intel Corporation S2600WP/S2600WP, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
> [ 19.388899] task: ffffffff81e0e4c0 task.stack: ffffffff81e00000
> [ 19.388904] RIP: 0010:[<ffffffff81837c48>] [<ffffffff81837c48>] eth_type_trans+0xe8/0x140
> [ 19.388904] RSP: 0000:ffff88081e803db8 EFLAGS: 00010297
> [ 19.388905] RAX: 0000000000000152 RBX: ffff88080221f200 RCX: 0000000000001073
> [ 19.388905] RDX: ffff8808013afdc0 RSI: ffff880801114000 RDI: ffff880819407c00
> [ 19.388906] RBP: ffff88081e803e20 R08: ffff880801114000 R09: 0000000000000800
> [ 19.388907] R10: ffff8808013afec0 R11: ffffea003fd5a880 R12: ffff880819407c00
> [ 19.388907] R13: ffff881033408000 R14: ffffc9000843e000 R15: 0000000000000158
> [ 19.388908] FS: 0000000000000000(0000) GS:ffff88081e800000(0000) knlGS:0000000000000000
> [ 19.388909] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 19.388910] CR2: ffff88103ffff000 CR3: 0000000001e07000 CR4: 00000000001406f0
> [ 19.388910] Stack:
> [ 19.388912] ffffffff816905a7 ffffea003fd5a880 ffffea0000000008 ffff88080221f050
> [ 19.388913] ffff88080221f000 0000004000000160 ffffea003fd5a880 0000000000000000
> [ 19.388915] 0000000000000040 0000000000000000 ffff88080221f050 ffff88100d216000

From what I can tell it looks like the size of the frame is 0x160 hex,
or 352.  For whatever reason we are only pulling 8 bytes into the
header which is giving us an skb->len of 352 (0x160), and a skb-
>data_len of 344 (0x158).  When we go to pull the 14 bytes for the
Ethernet header we end up at a skb->len of 338 (0x152) which is
resulting in the panic.

The question is how are we coming up with 8 instead of 14 which is the
lowest limit supported by eth_get_headlen? My first thought was there
is an incorrect sizeof(eth) instead of the sizeof(*eth) somewhere in
the code but I can't find anything like that anywhere.

Is there any way you can provide me with the net/ethernet/eth.o and
drivers/net/ethernet/igb/igb.o files?  With that I can look over the
assembler and verify if the proper code is being generated.  From what
I can tell it seems like I should have the exact same code being
generated by my compiler as I am able to get the same offsets/registers
using a stock gcc 6.2, but I am not seeing the issue. I don't have a
Debian/Ubuntu install to test with so it would be easier for me to just
compare the object files for your build versus what I have to verify
there isn't any funny business going on in terms of the translation of
"sizeof(*eth)" which might be coming up with the wrong value.

> [ 19.388915] Call Trace:
> [ 19.388919] <IRQ>
> [ 19.388919] [<ffffffff816905a7>] ? igb_clean_rx_irq+0x6a7/0x7d0
> [ 19.388921] [<ffffffff81690a52>] igb_poll+0x382/0x700
> [ 19.388922] [<ffffffff81690a67>] ? igb_poll+0x397/0x700
> [ 19.388925] [<ffffffff8180f2d7>] net_rx_action+0x217/0x360
> [ 19.388928] [<ffffffff81957fb4>] __do_softirq+0x104/0x2ab
> [ 19.388931] [<ffffffff81086961>] irq_exit+0xf1/0x100
> [ 19.388932] [<ffffffff81957cf4>] do_IRQ+0x54/0xd0
> [ 19.388935] [<ffffffff81955b8c>] common_interrupt+0x8c/0x8c
> [ 19.388938] <EOI> he question is how are we coming up with 8 instead of 14 which is the lowest limit supported by eth_get_headlen?

> [ 19.388938] [<ffffffff817c1d12>] ? cpuidle_enter_state+0x122/0x2e0
> [ 19.388939] [<ffffffff817c1f07>] cpuidle_enter+0x17/0x20
> [ 19.388942] [<ffffffff810c64c3>] call_cpuidle+0x23/0x40
> [ 19.388944] [<ffffffff810c66f4>] cpu_startup_entry+0x114/0x200
> [ 19.388946] [<ffffffff81947675>] rest_init+0x85/0x90
> [ 19.388950] [<ffffffff81ffbf5c>] start_kernel+0x407/0x414
> [ 19.388952] [<ffffffff81ffb120>] ? early_idt_handler_array+0x120/0x120
> [ 19.388953] [<ffffffff81ffb2d6>] x86_64_start_reservations+0x2a/0x2c
> [ 19.388955] [<ffffffff81ffb415>] x86_64_start_kernel+0x13d/0x14c
> [ 19.388968] Code: 00 04 00 00 c9 c3 48 33 86 70 03 00 00 48 c1 e0 10 48 85 c0 0f b6 87 90 00 00 00 75 28 83 e0 f8 83 c8 01 88 87 90 00 00 00 eb 82 <0f> 0b 0f b6 87 90 00 00 00 83 e0 f8 83 c8 03 88 87 90 00 00 00
> [ 19.388970] RIP [<ffffffff81837c48>] eth_type_trans+0xe8/0x140
> [ 19.388970] RSP <ffff88081e803db8>
> [ 19.388996] ---[ end trace 107996155a43a15c ]---
> [ 19.393422] Kernel panic - not syncing: Fatal exception in interrupt
>
>
> To reproduce:
>
> git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
> cd lkp-tests
> bin/lkp install job.yaml # job file is attached in this email
> bin/lkp run job.yaml
>
>
>
> Thanks,
> Kernel Test Robot
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