Re: [PATCH] nfs: clear_commit_release incorrectly handle truncated page

Trond Myklebust
2010-02-02T15:04:14Z

On Tue, 2010-02-02 at 13:36 +0300, Dmitry Monakhov wrote:
> After page was truncated it lost it's mapping, this result in null
> pointer dereference on bdi_stat update. In fact we have to decrement
> bdi_stat even for truncated pages, so let's pass correct mapping in
> function arguments. Patch against linux-2.6
> ##TEST_CASE
> /*
> Tast case for bug in nfs_clear_request_commit()
> caused by null pointer dereference in case of truncated page.
> It takes less than 10 minutes to reproduce the bug.

Something is wrong here. nfs_release_page() returns '0' if the
page has an associated write request (i.e. PagePrivate is set), and so
both invalidate_complete_page() and invalidate_complete_page2() will
fail.

So what is truncating the page?

Trond