On 04/18/2012 01:38 PM, Arun KS wrote: > Hi Dave, > > Thanks for your reply. > > On Wed, Apr 18, 2012 at 1:01 PM, Dave Hylands <dhylands@xxxxxxxxx > <mailto:dhylands@xxxxxxxxx>> wrote: > > Hi Arun, > > On Tue, Apr 17, 2012 at 11:44 PM, Arun KS <getarunks@xxxxxxxxx > <mailto:getarunks@xxxxxxxxx>> wrote: > > > > Hello Guys, > > > > System is working normal after this BUG. > > PC is at 0x400b4614, probably a mmaped address. > > > > Just wondering how can this BUG happen when a process is running > in user > > space. > > > > Can it be something like this > > 1) enter to kernel from userspace through some system call. > > 2) kernel disables the interrupt and return to user space. > > Don't do that > > > I don't do that. This scenario mentioned is a just a wild guess. > > > > 3) and now it can happen in user space? > > Because something in userspace made a blocking call which would cause > a context switch to occur and your driver erroneously left interrupts > disabled. > > In that case, my system should have been unstable afterwards if > interrupts are left disabled. But that is not happening. > > If we return to user space with interrupts disabled, can we switch back > again to kernel using a system cal(because interrupts are already disabled)? > Depends on how many CPUs you have - AFAICS the "interrupts disabled" discussion above applies to a single CPU.. so if you have other CPUs on your system, you could probably use the system for a little more time. There is a simple way to check if interrupts are indeed disabled as hypothesised: turn on the hard-lockup detector (See Documentation/lockup-watchdogs.txt for details on what it is and what config options you have to enable). You can even turn on the soft-lockup detector and see what you get. Setting the option to panic on hard-lockup/ soft-lockup/hung tasks would be even better, to debug the issue. Regards, Srivatsa S. Bhat _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
