Re: [PATCH linux-2.6.0-test10-mm1] filemap_fdatawait.patch

[Janet Morgan]

Janet Morgan wrote:

> Andrew Morton wrote:
>
> > Andrew Morton <akpm@xxxxxxxx> wrote:
> >  
> >
> > > Let me actually think about this a bit.
> > >   
> >
> >
> > Nasty.  The same race is present in 2.4.x...
> >
> > How's about we start new I/O in filemap_fdatawait() if the page is 
> > dirty?
> >
> >
> > diff -puN mm/filemap.c~a mm/filemap.c
> > --- 25/mm/filemap.c~a    2003-12-31 03:10:29.000000000 -0800
> > +++ 25-akpm/mm/filemap.c    2003-12-31 03:17:05.000000000 -0800
> > @@ -206,7 +206,13 @@ restart:
> >         page_cache_get(page);
> >         spin_unlock(&mapping->page_lock);
> >
> > -        wait_on_page_writeback(page);
> > +        lock_page(page);
> > +        if (PageDirty(page) && mapping->a_ops->writepage) {
> > +            write_one_page(page, 1);
> > +        } else {
> > +            wait_on_page_writeback(page);
> > +            unlock_page(page);
> > +        }
> >         if (PageError(page))
> >             ret = -EIO;
> >
> >
> >  
> That fixed the problem!  Stephen's testcase is running successfully on 
> 2.6.1-mm1 plus your patch -- no more uninitialized data!
Geez, I guess not.  While this was the first time the test ran 
successfully for me, it is not reproducible.  Subsequent runs on 
2.6.1-mm1 plus the above patch are seeing unintialized data.   Sorry for 
the false start.

-Janet


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