MmUnmapLockedPages causing Bugcheck B8

Archived from groups: microsoft.public.development.device.drivers,microsoft.public.windowsxp.device_driver.dev (More info?)

Hello Guys
My MmunMapLockedPages in IoCompletion routine is giving me Bugcheck B8 with
all the Args being NULL.
and moreever this happens only when the File system is NTFS.
Any ideas on how to proceed?
Has anyone come across these...

Sample code is as follows...

ASSERT((ewData->User)!=NULL);
ASSERT(Irp->MdlAddress!=NULL);
__try{
MmUnmapLockedPages(ewData->User, Irp->MdlAddress);
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
KdPrint(("\nError in MmUnmapLockedPages" ));
}

Regards
Shal

Archived from groups: microsoft.public.development.device.drivers,microsoft.public.windowsxp.device_driver.dev (More info?)

This means the OP calls unmap for user space address from a DPC.

"Jonathan Morrison [MSFT]" <jonathanm@mindspring.com> wrote in message
news5SKHeSXEHA.1048@tk2msftngp13.phx.gbl...
> Can you attach the kernel debugger to the machine and send the callstack
of
> the thread that is bugchecking. A B8 bugcheck is a
ATTEMPTED_SWITCH_FROM_DPC
> (b8) bugcheck. The callstack should show the offending driver.
>
> --
> This posting is provided "AS IS" with no warranties, and confers no
rights.
> Use of any included script samples are subject to the terms specified at
> http://www.microsoft.com/info/cpyright.htm
> "Shalini" <kandukondein@NOSPAMyahoo.com> wrote in message
> news:eiN3EBSXEHA.2964@TK2MSFTNGP09.phx.gbl...
> > Hello Guys
> > My MmunMapLockedPages in IoCompletion routine is giving me Bugcheck B8
> > with
> > all the Args being NULL.
> > and moreever this happens only when the File system is NTFS.
> > Any ideas on how to proceed?
> > Has anyone come across these...
> >
> > Sample code is as follows...
> >
> > ASSERT((ewData->User)!=NULL);
> > ASSERT(Irp->MdlAddress!=NULL);
> > __try{
> > MmUnmapLockedPages(ewData->User, Irp->MdlAddress);
> > }
> > __except (EXCEPTION_EXECUTE_HANDLER)
> > {
> > KdPrint(("\nError in MmUnmapLockedPages" ));
> > }
> >
> > Regards
> > Shal
> >
> >
>
>