lkml.org 
[lkml]   [2010]   [May]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
Subjectrace condition between udevd and modprobe (mtrr_add)
From
Hi, while booting an initrd image built off of BusyBox on a thousand
nodes, we hit a race on a couple of nodes. They hang during the boot
process with the stack traces listed below. The really simple init
script in the initrd does a 'udevd --daemon' and then modprobe of a
device. The device needs to assign an mtrr to the pci resource, and
instead the whole node hangs. Putting a 'sleep 1' in between these two
calls prevents any hangs.

mtrr_add_page and the buddy allocator code don't appear to share any
semaphores, and there isn't an obvious way in which this can hang.
Possibly the smp_call_function IPI isn't being handled by the other
cores... That's the best guess. Can anyone help sort this mess out?

Also, is there a better way to test that udevd is fully up? A 'sleep
1' is not the preferred solution here.

Thanks for your time,

-Kyle Hubert

>> ps
ADDR UID PID PPID STATE FLAGS CPU NAME
===============================================================================
...
0xffff88061d26c720 0 1036 1 0 0x400140 - udevd
0xffff88021e05c480 0 1037 1 0 0x400100 - modprobe
0xffff88081d072440 0 1116 1036 0 0x400040 - udevd
===============================================================================
135 active task structs found
>> bt 0xffff88021e05c480
================================================================
STACK TRACE FOR TASK: 0xffff88021e05c480(modprobe)

0 <schedule?> [0x0]
1 mtrr_add_page+494 [0xffffffff80219d9e]
2 <unknown?>+<ERROR> [0xffffffffa0009a08]
================================================================
>> bt 0xffff88061d25f420
================================================================
STACK TRACE FOR TASK: 0xffff88061d25f420(udevd)

0 <schedule?> [0x0]
1 __alloc_pages_internal+241 [0xffffffff80292731]
2 rmqueue_bulk+89 [0xffffffff80291b19]
3 get_page_from_freelist+1430 [0xffffffff802922e6]
4 __alloc_pages_internal+241 [0xffffffff80292731]
5 alloc_pages_current+168 [0xffffffff802b0898]
6 pte_alloc_one+49 [0xffffffff80229271]
7 __pte_alloc+67 [0xffffffff8029e7d3]
8 copy_page_range+1269 [0xffffffff802a11c5]
9 alloc_pid+744 [0xffffffff80250a18]
10 copy_process+3057 [0xffffffff8023bcf1]
11 do_fork+118 [0xffffffff8023c4d6]
12 sys_clone+35 [0xffffffff80209c23]
13 ptregscall_common+103 [0xffffffff8020bda7]
================================================================
>> bt 0xffff88081de869e0
================================================================
STACK TRACE FOR TASK: 0xffff88081de869e0(udevd)

0 <schedule?> [0x0]
1 set_user_nice+324 [0xffffffff80234734]
2 set_one_prio+113 [0xffffffff8024ea61]
3 sys_setpriority+129 [0xffffffff8024eb41]
4 system_call_fastpath+22 [0xffffffff8020ba3b]
================================================================


\
 
 \ /
  Last update: 2010-05-04 07:33    [W:0.059 / U:141.672 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site