Paul, On Mon, Jun 10, 2013 at 07:51:10AM -0700, Paul E. McKenney wrote: > On Mon, Jun 10, 2013 at 03:47:28PM +0800, Fengguang Wu wrote: > > Greetings, > > > > I got the below dmesg and the first bad commit is > > > > commit 911af505ef407c2511106c224dd640f882f0f590 > > Author: Paul E. McKenney <paul.mcken...@linaro.org> > > Date: Mon Feb 11 10:23:27 2013 -0800 > > > > rcu: Provide compile-time control for no-CBs CPUs > > > > Currently, the only way to specify no-CBs CPUs is via the rcu_nocbs > > kernel command-line parameter. This is inconvenient in some cases, > > particularly for randconfig testing, so this commit adds a new set of > > kernel configuration parameters. CONFIG_RCU_NOCB_CPU_NONE (the default) > > retains the old behavior, CONFIG_RCU_NOCB_CPU_ZERO offloads callback > > processing from CPU 0 (along with any other CPUs specified by the > > rcu_nocbs boot-time parameter), and CONFIG_RCU_NOCB_CPU_ALL offloads > > callback processing from all CPUs. > > > > Signed-off-by: Paul E. McKenney <paul.mcken...@linaro.org> > > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com> > > > > However I guess it's a wrong bisect, the commit should be unmasking an > > old bug because it merely provides more kconfig options. > > > > This warning happened only once in 74 boots of the kernel. > > > > I also attached the 2nd dmesg which shows boot hang for the same > > kernel. > > > > Note that there are also 2 kernel hangs in the 74 boots. It should > > not be an RCU problem, however for completeness, I also attach a dmesg > > for your reference when considering this RCU warning. > > Either way, that is a nasty warning! You get this on recent kernels as > well, I take it?
Yes, the warning is still in recent kernels, indicated from the last lines of the bisect log. 911af505ef407c2511106c224dd640f882f0f590 is bad and its parent 34ed62461ae4970695974afb9a60ac3df0086830 is good: > > git bisect bad 911af505ef407c2511106c224dd640f882f0f590 # 65 > > 2013-06-07 16:14:41 rcu: Provide compile-time control for no-CBs CPUs > > git bisect good 34ed62461ae4970695974afb9a60ac3df0086830 # 900 > > 2013-06-08 04:57:34 rcu: Remove restrictions on no-CBs CPUs After bisect, the script tries to confirm that 34ed62461ae4970695974afb9a60ac3df0086830 is really good by boot testing it 2700 more times: > > git bisect good 34ed62461ae4970695974afb9a60ac3df0086830 # 2700 > > 2013-06-10 14:33:56 rcu: Remove restrictions on no-CBs CPUs And continue to find out whether the linus/master and linux-next/master are good/bad (here the results are both bad): > > git bisect bad f43e7a34255a387930bc2bb826ec17c052ce975e # 14:34 0 > > Merge branch 'for-next' > > git bisect bad c04efed734409f5a44715b54a6ca1b54b0ccf215 # 14:41 11 > > Add linux-next specific files for 20130607 Thanks, Fengguang -- 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/
