On Tue, 2012-09-04 at 08:21 -0700, Tim Chen wrote:
> On Tue, 2012-08-21 at 17:48 -0700, Tim Chen wrote:
>
> >
> > Thanks to Matthew's suggestions on improving the patch. Here's the
> > updated version. It seems to be sane when I booted my machine up. I
> > will put it through more testing when I get a chance.
> >
> > Tim
> >
>
> Matthew,
>
> The new patch seems to be causing some of the workloads with mmaped file
> read to seg fault. Will need to dig further to find out why.
>
> Tim
>
Okay, the problem seems to be the code below. It is too restrictive and
causes some cases where the mutex needs to be taken in try_to_unmap_file
to be missed.
> > +int needs_page_mmap_mutex(struct page *page)
> > +{
> > + return page->mapping && page_mapped(page) && page_rmapping(page) &&
> > + !PageKsm(page) && !PageAnon(page);
> > +}
> > +
Changing the check to the following fixes the problem:
@@ -873,8 +873,7 @@ static int page_referenced_file(struct page *page,
int needs_page_mmap_mutex(struct page *page)
{
- return page->mapping && page_mapped(page) && page_rmapping(page) &&
- !PageKsm(page) && !PageAnon(page);
+ return page->mapping && !PageKsm(page) && !PageAnon(page);
}
I'll do more testing and generate a second version of the patch set with the fixes.
Tim
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