Messages in this thread |  | | | Date | Wed, 15 Nov 2006 11:24:26 -0800 | | From | Andrew Morton <> | | Subject | Re: Yet another borken page_count() check in invalidate_inode_pages2().... |
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On Wed, 15 Nov 2006 13:05:13 -0500 Trond Myklebust <Trond.Myklebust@netapp.com> wrote:
> On Wed, 2006-11-15 at 08:46 -0800, Andrew Morton wrote: > > > but nobody could have started another writeback after the "..." because they > > couldn't have got the lock_page(), and lock_page() is required for > > ->writepage()? > > Nothing can have called writepage(), but something may be calling > ->writepages(). That may call set_page_writeback without taking the page > lock. >
The protocol is
lock_page() set_page_writeback() ->writepage()
and there are various places which assume that nobody will start new writeout of a locked page. But I forget where they are - things have always been this way.
If NFS is running set_page_writeback() against an unlocked page then I don't know what will break. I didn't know it was doing that.
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