Hi,
Is it valid to access paged memory inside volume filter dispatch read
function (getting called at < dispatch level). I mean to ask whether
recursive page fault are allowed or not in windoows.
–
Regards
Rohit Gauba
“A positive thought is the seed of a positive result”
If this is not a pagefile read path - then yes.
–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com
“Rohit” wrote in message news:xxxxx@ntdev…
Hi,
Is it valid to access paged memory inside volume filter dispatch read function (getting called at < dispatch level). I mean to ask whether recursive page fault are allowed or not in windoows.
–
Regards
Rohit Gauba
“A positive thought is the seed of a positive result”
Thanks for the prompt response. If we create a shared memory backed by
pagefile and if pagefault occur while reading it, then we cannot access
paged memory in that page fault handling thread. Is it what you want to say?
On Fri, Aug 20, 2010 at 5:11 PM, Maxim S. Shatskih
wrote:
> If this is not a pagefile read path - then yes.
>
> –
> Maxim S. Shatskih
> Windows DDK MVP
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
> “Rohit” wrote in message news:xxxxx@ntdev…
> Hi,
>
> Is it valid to access paged memory inside volume filter dispatch read
> function (getting called at < dispatch level). I mean to ask whether
> recursive page fault are allowed or not in windoows.
>
> –
> Regards
> Rohit Gauba
>
> “A positive thought is the seed of a positive result”
>
> —
> NTDEV is sponsored by OSR
>
> For our schedule of WDF, WDM, debugging and other seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at
> http://www.osronline.com/page.cfm?name=ListServer
>
–
Regards
Rohit Gauba
“A positive thought is the seed of a positive result”
>occur while reading it, then we cannot access paged memory in that page fault handling thread.
Yes.
Pagefile IO paths must be nonpaged and must not touch anything pageable.
–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com
Thanks for clarification. I have one more doubt. In Rajeev Nagar book it was
mentioned in chap 5(page fault handling) “Note that the file system cannot
incur any page faults while trying to satisfy the paging I/O read request.”
Here paging IO is any disk/pagefile IO. It means double faults are not
allowed in windows. Please correct me if I am wrong
On Sat, Aug 21, 2010 at 2:52 AM, Maxim S. Shatskih
wrote:
> >occur while reading it, then we cannot access paged memory in that page
> fault handling thread.
>
> Yes.
>
> Pagefile IO paths must be nonpaged and must not touch anything pageable.
>
> –
> Maxim S. Shatskih
> Windows DDK MVP
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
> au
> —
> NTDEV is sponsored by OSR
>
> For our schedule of WDF, WDM, debugging and other seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at
> http://www.osronline.com/page.cfm?name=ListServer
>
–
Regards
Rohit Gauba
“A positive thought is the seed of a positive result”
It is more of an x86 family affair… Double fault not allowed. If allowed, then the question would be why not triple fault, or more fault’s to be allowed, and we get to an endless loop of faults …
-pro
On Aug 21, 2010, at 6:23 AM, Rohit wrote:
Thanks for clarification. I have one more doubt. In Rajeev Nagar book it was mentioned in chap 5(page fault handling) “Note that the file system cannot incur any page faults while trying to satisfy the paging I/O read request.” Here paging IO is any disk/pagefile IO. It means double faults are not allowed in windows. Please correct me if I am wrong
On Sat, Aug 21, 2010 at 2:52 AM, Maxim S. Shatskih wrote:
> >occur while reading it, then we cannot access paged memory in that page fault handling thread.
>
> Yes.
>
> Pagefile IO paths must be nonpaged and must not touch anything pageable.
>
> –
> Maxim S. Shatskih
> Windows DDK MVP
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
> au
> —
> NTDEV is sponsored by OSR
>
> For our schedule of WDF, WDM, debugging and other seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer
>
>
>
> –
> Regards
> Rohit Gauba
>
> “A positive thought is the seed of a positive result”
> — NTDEV is sponsored by OSR For our schedule of WDF, WDM, debugging and other seminars visit: http://www.osr.com/seminars To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer
>I/O read request." Here paging IO is any disk/pagefile IO. It means double faults are not allowed in
Define “double fault”.
I think most of the code dealing with page faults on memory-mapped files is pageable, and even the MmSt structure which lists the pages mapped to a file is pageable.
–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com
> In Rajeev Nagar book it was mentioned in chap 5(page fault handling) "Note that the file system
cannot incur any page faults while trying to satisfy the paging I/O read request."
It depends on the target of paging I/O read, which can be either mapped file or pagefile. In the former case
there is no problem with the nested page fault whatsoever. However, in the latter one…well, just think what happens if code that is needed to retrieve a page from the pagefile gets paged itself - you will get into an infinite chain of page faults. This is what the book meant to say…
Anton Bassov