From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Kenneth W" Date: Wed, 08 Mar 2006 21:59:03 +0000 Subject: RE: Fix race in the accessed/dirty bit handlers Message-Id: <200603082159.k28Lx3g12281@unix-os.sc.intel.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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