Re: 2.1.89

Benjamin C.R. LaHaise (blah@kvack.org)
Fri, 13 Mar 1998 00:17:29 -0500 (EST)


On Wed, 11 Mar 1998, Stephen C. Tweedie wrote:

> Hi,
>
> On Tue, 10 Mar 1998 12:40:03 +1300 (NZDT), "Peter T. Waltenberg"
> <peterw@karaka.chch.cri.nz> said:
>
> > VM: Found a writable swap-cached page!
> > VM: Found a writable swap-cached page!
> > ...
>
> What sort of load are you running on this box? Much in the way of
> memory mapped files, cloned threads or anything else that might help
> me home in on this?

If he is running clones, there is a race I just noticed between fork and
mmap that can lead to unexpected results (this fix is included in
the rev_pte patch). Here's the tidbit from kernel/fork.c:

if (retval)
goto free_mm;
+ down(&mm->mmap_sem);
retval = dup_mmap(mm);
+ up(&mm->mmap_sem);
if (retval)
goto free_pt;

-ben

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