В Пн, 20/10/2014 в 11:13 +0200, Peter Zijlstra пишет: > 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.
Now it's clearly for me. I though it's because task_struct freeing is slow. Thanks! > > > 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. I've sent one more patch with this: "[PATCH v3] sched/numa: fix unsafe get_task_struct() in task_numa_assign()" Kirill -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
