From: Jamey Kirby [jkirby@storagecraft.com]
Sent: Monday, April 17, 2000 3:28 PM
To: NT Developers Interest List
Subject: [ntdev] RE: A query !!

Interesting. I experienced this in my driver. Here is what I was finding:

If you lock the pages and call the FSD below you, the FSD will lock and
unlock the pages. There is no lock count, so your lock is gone. So, you not
unlocking the pages should be OK. If it is NPP, you should use
MmBuildMdlForNonPagedPool.

This means that your locked pages are no longer locked in your completion
handler. Are you using a completion handler? Are you accessing the buffers
in the completion handler?

Sorry I can not be more specific; it would help to see your code.

Jamey

> -----Original Message-----
> From: bounce-ntdev-562@lists.osr.com
> [mailto:bounce-ntdev-562@lists.osr.com]On Behalf Of Kiran Mandava
> Sent: Monday, April 17, 2000 12:17 PM
> To: NT Developers Interest List
> Subject: [ntdev] RE: A query !!
>
>
> Hi,
>
>  some more info on the current scenario,
>
>  The main scenario is i Create a MDL first time and reuse it all the time
> with the calls MmPrepareMdlForReuse + MmInitializeMdl.
>
> 1. we have a driver which does only MmProbeAndLockPages (There is no
> compensating call mmunlockpages)and everything worked fine until
> we got into
> something like heavy usage of NonPagedPool (70M) + LockingDown some of the
> Paged Pool In the Memory(about 30 MB) so the final kernel memory usage was
> something like 140 MB...
>    (everything works fine until the memory usage creeped upto 140
> MB, in the
> normal cases it was Around 90 MB and evrything works fine.)
>
>   but the problem at that point was something like i was observing a blue
> sreen after the whole system runs for a while (say 4 to 5 hours) the
> bugcheck being NO_MORE_SYSTEM_PTES (i don't know whether it is related or
> not but...)
>
> so once i fixed the stuff using the mmunlockpages it worked fine for two
> days and the page table entres were constant..
>   but after it crashed with the error IRQL_NOT_LESS_OR_EQUAL...which i
> suspect is due to the mmunlockpages..
>
> 2. I tried to Use the NT DDK specified MmbuildMDLforNonPagedPool
> and after a
> while (unpredcictable)the system blue screens with error
>    PFN_FILE_CORRUPT
>
>
>
> could somebody help me on this.
>
>
> thanks,
>
> >-----Original Message-----
> >From: Roddy, Mark [mailto:Mark_Roddy@stratus.com]
> >Sent: Monday, April 17, 2000 11:42 AM
> >To: NT Developers Interest List
> >Subject: [ntdev] RE: A query !!
> >
> >
> >
> >However it is an interesting question if
> >MmProbeAndLockPages/MmUnlockPages
> >cause a problem if the underlying buffer happens to be NPP.
> >One hopes not,
> >but I've heard several people swear that it does. How would a
> >driver even
> >know, other than through some a priori assumptions?
> >
> >> -----Original Message-----
> >> From: Jamey Kirby [mailto:jkirby@storagecraft.com]
> >> Sent: Monday, April 17, 2000 2:22 PM
> >> To: NT Developers Interest List
> >> Subject: [ntdev] RE: A query !!
> >>
> >>
> >> I think you need to use MmBuildMdlForNonPagedPool() if you
> >> use NPP in your
> >> MDL.
> >>
> >> Jamey
> >>
> >> > -----Original Message-----
> >> > From: Kiran Mandava [mailto:kiran.mandava@skystream.com]
> >> > Sent: Monday, April 17, 2000 11:08 AM
> >> > To: NT Developers Interest List
> >> > Subject: [ntdev] A query !!
> >> >
> >> >
> >> > The Microsoft Exchange Server received an Internet message
> >> that could
> >> > not be processed. To view the original message content, open the
> >> > attached message. <<message.txt>>
> >> >
> >>
> >>
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> >
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