Messages in this thread | | | Date | Fri, 30 May 2003 18:00:27 -0700 | From | Andrew Morton <> | Subject | Re: [RFC][PATCH] Convert do_no_page() to a hook to avoid DFS race |
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"Paul E. McKenney" <paulmck@us.ibm.com> wrote: > > Rediffed to 2.5.70-mm2. > > This patch allows a distributed filesystem to avoid the > pagefault/cross-node-invalidate race described in: > > http://marc.theaimsgroup.com/?l=linux-kernel&m=105286345316249&w=2 > > This patch converts the bulk of do_no_page() into a hook that may > be called from the ->nopage vm_operations_struct callout.
Seems reasonable.
> There > is still an inlined do_no_page() wrapper due to the fact that > do_anonymous_page() requires that the mm->page_table_lock be > held on entry, while the ->nopage callouts require that this > lock be dropped.
I sugest you change the ->nopage definition so that page_table_lock is held on entry to ->nopage, and ->nopage must drop it at some point. This gives the nopage implementations some more flexibility and may perhaps eliminate that special case?
> This patch is untested.
I don't think there's a lot of point in making changes until the code which requires those changes is accepted into the tree. Otherwise it may be pointless churn, and there's nothing in-tree to exercise the new features.
> An alternative to this patch includes the nopagedone() patch posted > moments ago. hch has also suggested that do_anonymous_page() be > converted to a ->nopage callout, but this would require that all > of the other ->nopage callouts drop mm->page_table_lock as their > first action. If people believe that this is the right thing to > do, I will happily produce such a patch.
That sounds better to me.
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