Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3

Andi Kleen
2009-05-28T13:42:29Z

On Thu, May 28, 2009 at 02:15:41PM +0200, Nick Piggin wrote:
> For correctness for what? You can't remove a page from swapcache or
> pagecache under writeback because then the mm thinks that location
> is not being used.

I'm adding wait_on_page_writeback() to memory_failure(), so
it will be out of the picture hopefully

>
>
> > I'm mainly interested in correctness (as in not crashing) of this
> > version now.
> >
> > Also writeback seems to be only used by nfs/afs/nilfs2, not in
> > the normal case, unless I'm misreading the code.
>
> I don't follow. What writeback are you talking about?

Sorry I misread the code, it's indeed used more commonly.

> > > Then the writeback pages simply won't reach here. And it won't
> > > magically go into writeback state, since the page has been locked.
> >
> > But since we take the page lock they should not be in writeback anyways,
> > no?
>
> No. PG_writeback was introduced so as to reduce page lock hold
> times (most of writeback runs without page lock held).

Ok. Then the wait_on_page_writeback() will take care of that.

Thanks for the feedback,

-Andi

--
ak@linux.intel.com -- Speaking for myself only.