> > > And it doesn't sound too hard to solve: when current algorithm doesn't
> > > seem to be making progress, then it will have to be done the hard way,
> > > searching for for all nonlinear ptes of a page to unmap.
> >
> > Ah, you see, but that is when you've already lost.
> >
> > The DoS is ab
On Thu, Mar 08, 2007 at 01:11:43PM +0100, Peter Zijlstra wrote:
> On Thu, 2007-03-08 at 12:48 +0100, Miklos Szeredi wrote:
> > > However this still leaves the non-linear reclaim (Nick pointed it out as
> > > a potential DoS and other people have corroborated this). I have no idea
> > > on that to d
On Thu, 2007-03-08 at 12:48 +0100, Miklos Szeredi wrote:
> > However this still leaves the non-linear reclaim (Nick pointed it out as
> > a potential DoS and other people have corroborated this). I have no idea
> > on that to do about that.
>
> OK, but that is a completely different problem, not a
> > - it's a maintenance burden: I'll have to layer the m/ctime update
> > patch on top of this
>
> But you have to update m/ctime for BDI_CAP_NO_WRITEBACK mappings anyway
> don't you?
Yes, but that's a different aspect of msync(), not about the data
writeback issues that nonlinear mappings
On Thu, Mar 08, 2007 at 12:21:01PM +0100, Miklos Szeredi wrote:
> > Partial revert of commit: 204ec841fbea3e5138168edbc3a76d46747cc987
> >
> > Non-linear vmas aren't properly handled by page_mkclean() and fixing that
> > would result in linear scans of all related non-linear vmas per
> > page_mkc
> However this still leaves the non-linear reclaim (Nick pointed it out as
> a potential DoS and other people have corroborated this). I have no idea
> on that to do about that.
OK, but that is a completely different problem, not affecting
page_mkclean() or msync().
And it doesn't sound too hard
On Thu, 2007-03-08 at 12:21 +0100, Miklos Szeredi wrote:
> > Partial revert of commit: 204ec841fbea3e5138168edbc3a76d46747cc987
> >
> > Non-linear vmas aren't properly handled by page_mkclean() and fixing that
> > would result in linear scans of all related non-linear vmas per
> > page_mkclean()
> Partial revert of commit: 204ec841fbea3e5138168edbc3a76d46747cc987
>
> Non-linear vmas aren't properly handled by page_mkclean() and fixing that
> would result in linear scans of all related non-linear vmas per page_mkclean()
> invocation.
>
> This is deemed too costly, hence re-instate the msy
On Wed, 2007-03-07 at 19:12 +0100, Peter Zijlstra wrote:
> On Wed, 2007-03-07 at 10:00 -0800, Linus Torvalds wrote:
> >
> > On Wed, 7 Mar 2007, Peter Zijlstra wrote:
> > >
> > > I'm not at all happy with this, but plain disallowing remap_file_pages on
> > > bdis
> > > without BDI_CAP_NO_WRITEBAC
On Wed, 2007-03-07 at 10:00 -0800, Linus Torvalds wrote:
>
> On Wed, 7 Mar 2007, Peter Zijlstra wrote:
> >
> > I'm not at all happy with this, but plain disallowing remap_file_pages on
> > bdis
> > without BDI_CAP_NO_WRITEBACK seems to offend some people, hence restrict it
> > to
> > root only.
On Wed, 7 Mar 2007, Peter Zijlstra wrote:
>
> I'm not at all happy with this, but plain disallowing remap_file_pages on bdis
> without BDI_CAP_NO_WRITEBACK seems to offend some people, hence restrict it to
> root only.
I don't think that's a viable approach. Nonlinear mappings would normally
b
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