RE: Fix race in the accessed/dirty bit handlers

From: Chen, Kenneth W <kenneth.w.chen_at_intel.com>
Date: 2006-03-09 08:59:03
Christoph Lameter wrote on Wednesday, March 08, 2006 7:33 AM
> On Wed, 8 Mar 2006, Robin Holt wrote:
> > Are you sure this does not lead to a data integrity issue.  What if we
> > have a clean writable page.  If we get started on the dirty handler and
> > the pte gets zapped from under us, the page would not get marked as dirty
> > (pte had not gotten updated yet) and the process would continue running.
> 
> No the process would not continue running. The page is not present and 
> therefore the page fault handler gets involved next to get the page back. 
> 
> The page fault handler gets invoked with the write flag set. So it 
> will bring back the page and mark it dirty. Then it will return to the 
> process which will perform the write operation.

What happens to a scenario where you zap the pte right after dirty bit
handler just finished.  Won't you lost that "dirty" information?

- Ken

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Received on Thu Mar 09 09:00:16 2006

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