Re: [PATCH 2.5.66-mm2] Fix page_convert_anon locking issues

[Andrew Morton <akpm@digeo.com>]

Dave McCracken <dmccr@us.ibm.com> wrote:
>
> 
> --On Wednesday, April 02, 2003 17:58:08 -0600 Dave McCracken
> <dmccr@us.ibm.com> wrote:
> 
> > It's looking more and more like we should use your other suggestion.  It's
> > definitely simpler if we can make it failsafe.  I'll code it up tomorrow.
> 
> I thought of a big hole in the simpler scheme you suggested.  It occurred
> to me that try_to_unmap will fail.  It will see the PageAnon flag so it'll
> just walk the pte_chain and assume it doesn't have to walk the vmas.  This
> will leave the page with some stranded mappings.  Actually
> page_convert_anon will then finish, and we'll have a page where
> try_to_unmap claims it has succeeded but still has mappings.
> 

Lock the page, and page reclaim will not go near it.  It needs to be locked
across page_convert_anon() anyway, to protect ->mapping.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"aart@kvack.org">aart@kvack.org</a>