From mboxrd@z Thu Jan 1 00:00:00 1970 From: paulmck@linux.vnet.ibm.com (Paul E. McKenney) Date: Mon, 24 Sep 2012 15:00:23 -0700 Subject: rcu self-detected stall messages on OMAP3, 4 boards In-Reply-To: References: <20120921212054.GE2454@linux.vnet.ibm.com> <20120922000537.GH2454@linux.vnet.ibm.com> <20120922195253.GD2934@linux.vnet.ibm.com> <20120922231733.GI2934@linux.vnet.ibm.com> Message-ID: <20120924220023.GG2477@linux.vnet.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Sep 24, 2012 at 09:54:00PM +0000, Paul Walmsley wrote: > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > On Sat, Sep 22, 2012 at 10:20:19PM +0000, Paul Walmsley wrote: > > > On Sat, 22 Sep 2012, Paul E. McKenney wrote: > > > > > > > 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 > > > Date: Tue Jun 5 15:53:53 2012 -0700 > > > > > > rcu: Fix qlen_lazy breakage > > > > You lost me on this one. This is already in mainline, so if you were > > using (say) 3.6-rc6, you would already have this commit applied. > > If I check out a kernel at this commit > 4fa3b6cb1bc8c14b81b4c8ffdfd3f2500a7e9367 + the > zero-callback-in-tickless-idle diagnostic patch, build and boot it, then > the stall warnings don't appear (in 25 minutes of testing). > > Messages from the diagnostic patch indicate that the kernel is entering > idle during a grace period with no RCU callbacks, though. > > This is not a big deal and does not need any further attention. Just > wanted to place a time boundary on the point when these messages started > appearing. (It is unlikely to be an optimal bound: i.e., there are > probably later commits where the warnings also don't appear.) Ah, got it, thank you! Thanx, Paul