lkml.org 
[lkml]   [2009]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009
On Fri, Jan 2, 2009 at 4:21 PM, Chris Adams <cmadams@hiwaay.net> wrote:
> Once upon a time, Linas Vepstas <linasvepstas@gmail.com> said:
>> Below follows a summary of the reported crashes. I'm ignoring the
>> zillions of "mine didn't crash" reports, or the "you're a paranoid
>> conspiracy theorist, its random chance" reports.
>
> I have reproduced this and got a stack trace (this is with Fedora 8 and
> kernel kernel-2.6.26.6-49.fc8.x86_64):
>
[snip]
> Basically (to my untrained eye), the leap second code is called from the
> timer interrupt handler, which holds xtime_lock. The leap second code
> does a printk to notify about the leap second. The printk code tries to
> wake up klogd (I assume to prioritize kernel messages), and (under some
> conditions), the scheduler attempts to get the current time, which tries
> to get xtime_lock => deadlock.

This analysis looks correct to me.

Grrrr. This has bit us a few times since the "no printk while holding
the xtime lock" restriction was added.

Thomas: Do you think this warrents adding a check to the printk path
to make sure the xtime lock isn't held? This way we can at least get a
warning when someone accidentally adds a printk or calls a function
that does while holding the xtime_lock.

thanks
-john


\
 
 \ /
  Last update: 2009-01-06 03:25    [W:0.183 / U:2.740 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site