On Mon, 24 Sep 2007 18:18:30 +0530 Balbir Singh <[EMAIL PROTECTED]> wrote:
> Peter Zijlstra wrote: > >>> Only kswapd can do this, direct reclaim has deadlock potential. > >> Yes, but not in all cases, do you want to add any gfp_mask > >> based smartness for direct reclaim? > > > > gfp_mask doesn't carry the needed information. It depends on whether > > the current context holds a rcu_read_lock(). > > > > What I meant was that nobody would hold rcu_read_lock() and pass > gfp_mask of GFP_KERNEL in scan_control or to do_try_to_free_pages() > > > so something like: > > > > rcu_read_lock() > > foo = kmalloc(sizeof(foo)) > > At this point, you really can't use GFP_KERNEL, since rcu_read_lock() > disables pre-emption in the current kernel, ideally you should see > a might_sleep() BUG. > > > new_slab() > > __alloc_pages() > > try_to_free_pages() > > synchronise_rcu() <-- deadlock > > rcu_read_unlock() I guess I've been using preemptibe rcu for way too long. Would need to clean up some of -rt to make this true there, but should be doable indeed. - 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/
