I agree with Alex's reasoning, plus in a multiprocessor environment such page zeroing may be done asynchronously to other cores or processors attempting to acquire use of that page while its state is inconsistent. Removing it counts as a security hole, in other words, except for single core processors that have interrupts disabled, that I see.
Sent from Outlook Mobile<https://aka.ms/blhgte> ________________________________ From: Ros-dev <ros-dev-boun...@reactos.org> on behalf of Alex Ionescu <ion...@videotron.ca> Sent: Sunday, May 10, 2020 12:37:09 PM To: ReactOS Development List <ros-dev@reactos.org>; Thomas Faber <thomas.fa...@reactos.org> Cc: Linda Wang <ros-di...@reactos.org> Subject: Re: [ros-dev] [ros-diffs] [reactos] 02/02: [NTOS:MM] Get rid of unnecessary MmZeroingPageThreadActive. I know I probably don't have much weight anymore but, I re-iterate that one of the goals of the project should be to make things as similar as possible for debugging/troubleshooting and learning as Server 2003... which does have this variable. I don't think it's the end of the world to keep it around. Stuff like this also tends to break kdexts.dll. Best regards, Alex Ionescu On Mon, Apr 6, 2020 at 5:15 AM Thomas Faber <thomas.fa...@reactos.org> wrote: > > https://git.reactos.org/?p=reactos.git;a=commitdiff;h=25a5aee86f43e9f526d4d360e4e4f35feb9d22b4 > > commit 25a5aee86f43e9f526d4d360e4e4f35feb9d22b4 > Author: Thomas Faber <thomas.fa...@reactos.org> > AuthorDate: Sat Feb 22 12:31:54 2020 +0100 > Commit: Thomas Faber <thomas.fa...@reactos.org> > CommitDate: Mon Apr 6 11:13:55 2020 +0200 > > [NTOS:MM] Get rid of unnecessary MmZeroingPageThreadActive. > --- > ntoskrnl/mm/ARM3/miarm.h | 1 - > ntoskrnl/mm/ARM3/mminit.c | 5 ++--- > ntoskrnl/mm/ARM3/pfnlist.c | 3 +-- > ntoskrnl/mm/ARM3/zeropage.c | 3 +-- > 4 files changed, 4 insertions(+), 8 deletions(-) > > diff --git a/ntoskrnl/mm/ARM3/miarm.h b/ntoskrnl/mm/ARM3/miarm.h > index c242b795af6..9d85c42afff 100644 > --- a/ntoskrnl/mm/ARM3/miarm.h > +++ b/ntoskrnl/mm/ARM3/miarm.h > @@ -639,7 +639,6 @@ extern PMMPDE MiHighestUserPde; > extern PFN_NUMBER MmSystemPageDirectory[PPE_PER_PAGE]; > extern PMMPTE MmSharedUserDataPte; > extern LIST_ENTRY MmProcessList; > -extern BOOLEAN MmZeroingPageThreadActive; > extern KEVENT MmZeroingPageEvent; > extern ULONG MmSystemPageColor; > extern ULONG MmProcessColorSeed; > diff --git a/ntoskrnl/mm/ARM3/mminit.c b/ntoskrnl/mm/ARM3/mminit.c > index 7cd7af10838..d72e7186193 100644 > --- a/ntoskrnl/mm/ARM3/mminit.c > +++ b/ntoskrnl/mm/ARM3/mminit.c > @@ -2181,9 +2181,8 @@ MmArmInitSystem(IN ULONG Phase, > /* Initialize the Loader Lock */ > KeInitializeMutant(&MmSystemLoadLock, FALSE); > > - /* Set the zero page event */ > - KeInitializeEvent(&MmZeroingPageEvent, SynchronizationEvent, FALSE); > - MmZeroingPageThreadActive = FALSE; > + /* Set up the zero page event */ > + KeInitializeEvent(&MmZeroingPageEvent, NotificationEvent, FALSE); > > /* Initialize the dead stack S-LIST */ > InitializeSListHead(&MmDeadStackSListHead); > diff --git a/ntoskrnl/mm/ARM3/pfnlist.c b/ntoskrnl/mm/ARM3/pfnlist.c > index eac3a043418..f175541a500 100644 > --- a/ntoskrnl/mm/ARM3/pfnlist.c > +++ b/ntoskrnl/mm/ARM3/pfnlist.c > @@ -701,10 +701,9 @@ MiInsertPageInFreeList(IN PFN_NUMBER PageFrameIndex) > ColorTable->Count++; > > /* Notify zero page thread if enough pages are on the free list now */ > - if ((ListHead->Total >= 8) && !(MmZeroingPageThreadActive)) > + if (ListHead->Total >= 8) > { > /* Set the event */ > - MmZeroingPageThreadActive = TRUE; > KeSetEvent(&MmZeroingPageEvent, IO_NO_INCREMENT, FALSE); > } > > diff --git a/ntoskrnl/mm/ARM3/zeropage.c b/ntoskrnl/mm/ARM3/zeropage.c > index 6d859f6806f..5fe22294199 100644 > --- a/ntoskrnl/mm/ARM3/zeropage.c > +++ b/ntoskrnl/mm/ARM3/zeropage.c > @@ -17,7 +17,6 @@ > > /* GLOBALS > ********************************************************************/ > > -BOOLEAN MmZeroingPageThreadActive; > KEVENT MmZeroingPageEvent; > > /* PRIVATE FUNCTIONS > **********************************************************/ > @@ -73,7 +72,7 @@ MmZeroPageThread(VOID) > { > if (!MmFreePageListHead.Total) > { > - MmZeroingPageThreadActive = FALSE; > + KeClearEvent(&MmZeroingPageEvent); > MiReleasePfnLock(OldIrql); > break; > } > _______________________________________________ Ros-dev mailing list Ros-dev@reactos.org http://reactos.org/mailman/listinfo/ros-dev
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