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

Nick Piggin
2009-06-09T10:49:21Z

On Tue, Jun 09, 2009 at 02:48:55PM +0800, Wu Fengguang wrote:
> On Mon, Jun 08, 2009 at 10:46:53PM +0800, Nai Xia wrote:
> > I meant PG_writeback stops writers to index---->struct page mapping.
>
> It's protected by the radix tree RCU locks. Period.
>
> If you are referring to the reverse mapping: page->mapping is procted
> by PG_lock. No one should make assumption that it won't change under
> page writeback.

Well... I think probably PG_writeback should be enough. Phrased another
way: I think it is a very bad idea to truncate PG_writeback pages out of
pagecache. Does anything actually do that?