Re: [patch] mm: recheck lock rlim after f_op->mmap() method

[Christoph Hellwig <hch@infradead.org>]

On Tue, Jul 10, 2007 at 06:27:05PM +0100, Hugh Dickins wrote:
> On Mon, 9 Jul 2007, Dmitry Monakhov wrote:
> > Some device drivers can change vm_flags in their f_op->mmap
> > method. In order to be on the safe side we have to recheck
> > lock rlimit. Now we have to check lock rlimit from two places,
> > let's move this common code to helper functon.
> > 
> > Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> > ---
> >  mm/mmap.c |   33 ++++++++++++++++++++++++++-------
> >  1 files changed, 26 insertions(+), 7 deletions(-)
> 
> Or would this simpler patch be the right one?  I suspect the
> mspec driver only says VM_LOCKED because of a deep-seated but
> irrational fear that its pages might fall into reclaim.

Looks good.  We probably should add a debug check to do_mmap_pgoff
so that ->mmap methods don't change flags that are not for drivers.

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