[dpdk-dev] [PATCH 2/2] but/pci: fix fd close for hot-unplug

Jeff Guo jia.guo at intel.com
Fri Nov 9 04:26:20 CET 2018


On 11/9/2018 5:55 AM, Stephen Hemminger wrote:
> On Thu, 8 Nov 2018 11:10:29 +0800
> Jeff Guo <jia.guo at intel.com> wrote:
>
>> hi, stephen
>>
>> On 11/8/2018 3:33 AM, Stephen Hemminger wrote:
>>> On Wed,  7 Nov 2018 17:41:31 +0800
>>> Jeff Guo <jia.guo at intel.com> wrote:
>>>   
>>>> When device is hot-unplugged, the device fd will be deleted in kernel.
>>>> Then in the progress of detaching device, if it try to close the fd,
>>>> it will cause a kernel crash, which shown a kernel null pointer error.
>>> If this happens, then it is a kernel bug and the kernel should be fixed.
>>> Working around it in userspace is not a great long term solution.
>>
>> agree with you. The key is sometime hold by kernel. But i think it is at
>> least reasonable for avoiding no-use process in user space, whatever
>> kernel's behavior. I am not sure if there is any better idea we can
>> find, but seems it is an option now.
> Are you using igb_uio?  If so the problem is an DPDK supplied driver.
> Let's fix that.  What is the backtrace on kernel crash.


yes, i am using the igb_uio. The back trace shown as below. It is an 
kernel NULL pointer result of uio wirte error in the eal-intr-thread 
thread,

################

[ 1052.262696] igb_uio 0000:00:03.0: mapping 1K dma=0x61cea000 
host=ffff8e94e1cea000
[ 1052.262699] igb_uio 0000:00:03.0: unmapping 1K dma=0x61cea000 
host=ffff8e94e1cea000
[ 1065.140839] igb_uio 0000:00:03.0: uio device registered with irq 24
[ 1078.006619] BUG: unable to handle kernel NULL pointer dereference at 
00000000000001d0
[ 1078.006657] IP: uio_write+0x2e/0xc0 [uio]
[ 1078.006659] PGD 70837067
[ 1078.006659] PUD 3440c067
[ 1078.006660] PMD 0

[ 1078.006667] Oops: 0000 [#1] SMP
[ 1078.006677] Modules linked in: igb_uio(OE) uio sb_edac edac_core 
kvm_intel kvm irqbypass crct10dif_pclmul joydev input_leds mac_hid 
i2c_piix4 crc32_pclmul ghash_clmulni_intel pcbc aesni_intel aes_x86_64 
crypto_simd glue_helper cryptd serio_raw parport_pc ppdev lp parport 
autofs4 8139too psmouse 8139cp ixgbevf mii pata_acpi floppy
[ 1078.006703] CPU: 3 PID: 14043 Comm: eal-intr-thread Tainted: 
G           OE   4.10.0-28-generic #32~16.04.2-Ubuntu
[ 1078.006705] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), 
BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 1078.006706] task: ffff8e94f3904380 task.stack: ffffa97b810dc000
[ 1078.006709] RIP: 0010:uio_write+0x2e/0xc0 [uio]
[ 1078.006712] RSP: 0018:ffffa97b810dfe90 EFLAGS: 00010246
[ 1078.006714] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 
ffffa97b810dff18
[ 1078.006715] RDX: 0000000000000004 RSI: 00007f75a0c45294 RDI: 
ffff8e94f3ff8d00
[ 1078.006716] RBP: ffffa97b810dfeb0 R08: ffffffffc01b6320 R09: 
ffff8e94e1de9370
[ 1078.006717] R10: ffff8e94f3ff8d38 R11: ffff8e94f382f9c0 R12: 
ffff8e94f2f94218
[ 1078.006718] R13: 00007f75a0c45294 R14: ffff8e94f3ff8d00 R15: 
0000000000000000
[ 1078.006719] FS:  00007f75a0c47700(0000) GS:ffff8e95bfcc0000(0000) 
knlGS:0000000000000000
[ 1078.006720] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1078.006721] CR2: 00000000000001d0 CR3: 0000000073abc000 CR4: 
00000000001406e0
[ 1078.006727] Call Trace:
[ 1078.006765]  __vfs_write+0x18/0x40
[ 1078.006768]  vfs_write+0xb8/0x1b0
[ 1078.006770]  SyS_write+0x55/0xc0
[ 1078.006791]  entry_SYSCALL_64_fastpath+0x1e/0xad
[ 1078.006793] RIP: 0033:0x7f75a10224bd
[ 1078.006796] RSP: 002b:00007f75a0c45270 EFLAGS: 00003293 ORIG_RAX: 
0000000000000001
[ 1078.006800] RAX: ffffffffffffffda RBX: 000000000000010c RCX: 
00007f75a10224bd
[ 1078.006801] RDX: 0000000000000004 RSI: 00007f75a0c45294 RDI: 
0000000000000010
[ 1078.006802] RBP: 00007f75a0c45250 R08: 00000000000010ed R09: 
00000000010922e7
[ 1078.006803] R10: 0000000001777781 R11: 0000000000003293 R12: 
00007f75a0c45680
[ 1078.006804] R13: 00007fff9036bb4f R14: 00007f75a0c479c0 R15: 
0000000000000000
[ 1078.006805] Code: 00 00 55 48 89 e5 41 54 53 48 83 ec 10 65 48 8b 04 
25 28 00 00 00 48 89 45 e8 31 c0 48 8b 87 c8 00 00 00 4c 8b 20 49 8b 44 
24 38 <48> 83 b8 d0 01 00 00 00 74 6a 48 89 d3 48 c7 c2 ea ff ff ff 48
[ 1078.006832] RIP: uio_write+0x2e/0xc0 [uio] RSP: ffffa97b810dfe90
[ 1078.006832] CR2: 00000000000001d0
[ 1078.006837] ---[ end trace 88c298c83fcf2c2d ]---

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