OK, I think I'm finally awake enough to see what you're all talking about :-)
On Sun, Oct 19, 2014 at 09:37:44PM +0200, Oleg Nesterov wrote: > > > RT tree has: > > > > > > https://git.kernel.org/cgit/linux/kernel/git/paulg/3.10-rt-patches.git/ > > > tree/patches/sched-delay-put-task.patch (answering the other email asking about this) RT does this because we call put_task_struct() with preempt disabled and on RT the memory allocator has sleeping locks. > > Yes, and this obviously implies more rcu callbacks in flight, and another > > gp before __put_task_struct(). but may be we will need to do this anyway... > > Forgot to mention... Or we can make task_struct_cachep SLAB_DESTROY_BY_RCU, > in this case ->curr (or any other "task_struct *" ponter) can not go away > under rcu_read_lock(). task_numa_compare() still needs the PF_EXITING check, > but we do not need to recheck ->curr or probe_kernel_read(). I think I would prefer SLAB_DESTROY_BY_RCU for this, because as you pointed out, I'm not sure mainline would like the extra callbacks. -- 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/
