Re: [PATCH] per-backing dev unplugging #2

[Chris Mason]

On Fri, 2004-03-12 at 15:03, Andrew Morton wrote:
> Chris Mason <mason@xxxxxxxx> wrote:
> >
> > During a mixed load test including fsx-linux and a bunch of procs
> > running cp/read/rm loops, I got a null pointer deref with the call
> > trace:
> > 
> > __lock_page->sync_page->block_sync_page
> > 
> > I don't see how we can trust page->mapping in this path, can't it
> > disappear?  If so, it would be a bug without Jens' patch too, just
> > harder to hit.
> 
> yup.  I wonder why you hit it now.

> This should be sufficient.  All callers of lock_page() should have a ref on
> the inode so ->mapping should be stable even if truncate whips the page off
> the inode.
> 
I thought the same thing, but blk_run_address_space does an if(mapping)
check already.  Looking deeper...

-chris




-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/