On Tue, 2006-12-19 at 16:03 -0800, Andrew Morton wrote: > On Tue, 19 Dec 2006 18:19:38 -0500 > Trond Myklebust <[EMAIL PROTECTED]> wrote: > > > NFS: Fix race in nfs_release_page() > > > > invalidate_inode_pages2() may set the dirty bit on a page owing to the > > call > > to unmap_mapping_range() after the page was locked. In order to fix > > this, > > NFS has hooked the releasepage() method. This, however leads to > > deadlocks > > in other parts of the VM. > > hmm, subtle. > > > Fix is to add a new callback: flushpage(), which will write out a dirty > > page that is under the page lock. > > > > I guess this might permit us to clean up some of the nasties in > invalidate_inode_pages2() - if the page comes dirty again, write it again. > But the requirement that the page remain locked makes it hard. Need to > think about it some more.
This was one of the reasons why I had to introduce nfs_writepage_locked() for 2.6.20 (the other reason being readpage()). The problem is that you can only protect against redirtying of the page by holding the page lock across the call to unmap_mapping_range(), the page writeout and the page removal. > Are you sure this is the cause of the NFS problem? > > > .prepare_write = nfs_prepare_write, > > .commit_write = nfs_commit_write, > > .invalidatepage = nfs_invalidate_page, > > - .releasepage = nfs_release_page, > > A NULL ->releasepage means that try_to_release_page() will call > try_to_free_buffers() if PagePrivate(). I suspect you'll need a stub to > prevent this. Ack, I'll add one in. If PagePrivate() is set during the call to try_to_release_page(), then the page should never be freeable. > (We were supposed to stop doing that about four years ago - change it so > that all a_ops must implement ->releasepage, but nobody got around to it). Would you still be interested in seeing this done? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
