Messages in this thread | | | Date | Sat, 22 Sep 2012 22:20:19 +0000 (UTC) | From | Paul Walmsley <> | Subject | Re: rcu self-detected stall messages on OMAP3, 4 boards |
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Hi Paul
On Sat, 22 Sep 2012, Paul E. McKenney wrote:
> Strangely enough, I believe that I have inadvertently fixed this in > my -rcu tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next > > Nevertheless, if you get a chance to try it, I would be interested to > hear if my guess is correct.
Yes, good news: the stall warnings go away with that branch.
> The trick is that a kthread drives the grace period in -rcu, regardless > of whether or not there are callbacks.
This is "rcu: Move quiescent-state forcing into kthread" ?
Added some debugging into rcu_gp_kthread() after that commit and can confirm that the quiescent-state forcing loop does start a few times when there are zero callbacks pending (modulo any races in my measurement code).
> However, the backport would not be something that -stable would be happy > with, so I will be putting together a fix for mainline. This thing > has been in the kernel since about 2004, not sure why you didn't hit > it earlier.
One other data point in that regard - noticed the warnings don't appear when the board is booted with:
commit 4fa3b6cb1bc8c14b81b4c8ffdfd3f2500a7e9367 Author: Paul E. McKenney <paul.mckenney@linaro.org> Date: Tue Jun 5 15:53:53 2012 -0700
rcu: Fix qlen_lazy breakage
...
- Paul
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