On Sat, 28 Apr 2007 06:13:39 +0100 (BST) Hugh Dickins <[EMAIL PROTECTED]> wrote:
> On Fri, 27 Apr 2007, Andrew Morton wrote: > > > > hm, could do. might_sleep() is intertwined with preempt in complex ways, > > but we did decouple that at the config level. no_mmap_sem() will dtrt for > > all preempt settings. > > > > But I'll be keeping this as a -mm-only debug patch (which brings us up to > > about thirty of 'em), so I think it's best to make it unconfigurable so we > > get maximum coverage. > > > > That's if it actually works. I haven't tried running it yet, and I have a > > feeling that running it might cause a big "doh" moment. We'll see. > > Yes, I'm expecting the crucial > > > + WARN_ON(rwsem_is_locked(&mm->mmap_sem)) > > to give a bogus warning every time another thread (or /proc, > or swapoff, or whatever) happens to have this mmap_sem locked. > might_sleep() is quite different, works on our thread's info. > Yes. lockdep has a way of working out if this task already has a particular lock for reading or writing, but it isn't immediately obvious how to extract that. I guess a simple hack would be do do a down_read() on it. If it's already held for reading, lockdep should warn. If it's already held for writing someone will notice. Oh well, it's not my top priority. - 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/
