[ros-bugs] [Bug 942] cache_manager_rewrite: Bugcheck when starting Opera 8.51

[ReactOS.Bugzilla at reactos.org]

http://www.reactos.org/bugzilla/show_bug.cgi?id=942





------- Additional Comments From maarten.paul at bosma.de  2006-04-02 20:51 CET -------
So here is what happens in a nutshell:

a) The cache manager creates MEMORY_AREA_CACHE_SEGMENT 

b) Later it maps a address rage in that area, but does not attached a page 
c) Then it accesses that address
d) because there is not page attached yet a page fault occurs
e) KiTrap8 => KiPageFaultHandler => MmNotPresentFault =>
MmNotPresentFaultSectionView => MmspNotPresentFaultDataFileSectionView =>
MmspReadSectionSegmentPages => MmspRequestPages 
f) MmspRequestPages calls MmRequestPageMemoryConsumer to request pages of type
MC_USER

g) When reactos get low on memory it calls MmTrimUserMemory which uses
MmPageOutPhysicalAddress with our page as parameter
h) MmPageOutPhysicalAddress bugchecks because it does not know about
MEMORY_AREA_CACHE_SEGMENT 

So the possible fixes would be
a) make the page fault handler create memory with MC_CACHE
b) make the cache manger request the pages instead of the page fault handler

I have a patch for a) but Alex said that is would be a hack.

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