Re: frequent lockups in 3.18rc4

[DÃniel Fraga]

On Tue, 2 Dec 2014 10:42:02 -0800
"Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:

> I was actually suggesting something a bit different.  Instead of bisecting
> by release, bisect by code.  The procedure is as follows:
> 
> 1.	I figure out some reliable way of making RCU allow preemption to
> 	be disabled for some RCU read-side critical sections, but not for
> 	others.  I send you the patch, which has rcu_read_lock_test()
> 	as well as rcu_read_lock().
> 
> 2.	You build a kernel without my Kconfig hack, with my patch from
> 	#1 above, and build a kernel with CONFIG_PREEMPT=y (which of
> 	course implies CONFIG_TREE_PREEMPT_RCU=y, given that you are
> 	building without my Kconfig hack).
> 
> 3.	You make a list of all the rcu_read_lock() uses in the kernel
> 	(or ask me to provide it).  You change the rcu_read_lock()
> 	calls in the first half of this list to rcu_read_lock_test().
> 
> 	If the kernel locks up as easily with this change as it did
> 	in a stock CONFIG_PREEMPT=y CONFIG_TREE_PREEMPT_RCU=y kernel,
> 	change half of the remaining rcu_read_lock() calls to
> 	rcu_read_lock_test().  If the kernel is much more resistant
> 	to lockup, change half of the rcu_read_lock_test() calls
> 	back to rcu_read_lock().

	Ok Paul, I want to do everything I can to help you debug this.

	So can you provide me the list you mentioned at point 3 (or
tell me how can I get it)? If you guide me through this, I can do
whatever you need. Thanks!

-- 
Linux 3.17.0-rc6-00235-gb94d525: Shuffling Zombie Juror
http://www.youtube.com/DanielFragaBR
http://exchangewar.info
Bitcoin: 12H6661yoLDUZaYPdah6urZS5WiXwTAUgL
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/