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Message-ID: <BANLkTi=ntjm-5D=OD1oFogpNjmJSJiZygQ@mail.gmail.com> Date: Sun, 24 Apr 2011 01:04:31 +0200 From: Sedat Dilek <sedat.dilek@...glemail.com> To: paulmck@...ux.vnet.ibm.com Cc: Stephen Rothwell <sfr@...b.auug.org.au>, linux-next@...r.kernel.org, LKML <linux-kernel@...r.kernel.org> Subject: Re: linux-next: Tree for April 14 (Call-traces: RCU/ACPI/WQ related?) On Sat, Apr 23, 2011 at 11:16 PM, Sedat Dilek <sedat.dilek@...glemail.com> wrote: > On Sat, Apr 23, 2011 at 11:05 PM, Paul E. McKenney > <paulmck@...ux.vnet.ibm.com> wrote: >> On Fri, Apr 22, 2011 at 07:36:58PM +0200, Sedat Dilek wrote: >>> On Fri, Apr 22, 2011 at 5:02 PM, Paul E. McKenney >>> <paulmck@...ux.vnet.ibm.com> wrote: >>> > On Fri, Apr 22, 2011 at 11:40:54AM +0200, Sedat Dilek wrote: >>> >> On Fri, Apr 22, 2011 at 2:50 AM, Paul E. McKenney >>> >> <paulmck@...ux.vnet.ibm.com> wrote: >>> >> > On Thu, Apr 21, 2011 at 04:47:31PM +0200, Sedat Dilek wrote: >>> >> >> On Thu, Apr 21, 2011 at 4:28 PM, Paul E. McKenney >>> >> >> <paulmck@...ux.vnet.ibm.com> wrote: >>> >> >> > On Thu, Apr 21, 2011 at 02:49:37PM +0200, Sedat Dilek wrote: >>> >> >> >> On Thu, Apr 21, 2011 at 12:24 PM, Sedat Dilek >>> >> >> >> <sedat.dilek@...glemail.com> wrote: >>> >> > >>> >> > [ . . . ] >>> >> > >>> >> >> >> Here the results from the 2nd-run (PREEMPT_RCU enabled). >>> >> >> > >>> >> >> > OK, and the grace periods clearly stopped advancing early on. >>> >> >> > >>> >> >> > Beyond that point, the per-CPU kthread is blocked, but RCU has some >>> >> >> > work for it to do. So someone has called invoke_rcu_cpu_kthread(), >>> >> >> > but rcu_cpu_kthread() is still blocked. I don't see a bug right >>> >> >> > off-hand, but it is early in the morning for me, so I might easily >>> >> >> > be missing something. >>> >> >> > >>> >> >> > Hmmm... >>> >> >> > >>> >> >> > The synchronization between these two assumes that the per-CPU >>> >> >> > kthread is always bound to the respective CPU, so if was somehow >>> >> >> > being migrated off, that might explain these results. >>> >> >> > >>> >> >> > I will add some more diagnostics, test them locally, then push >>> >> >> > out an update. Seem reasonable? >>> >> >> > >>> >> >> > And thank you again for the testing!!! >>> >> >> >>> >> >> Ping me when you have new stuff for testing. >>> >> >> Tomorrow (friday), here is public holiday and monday, too. >>> >> >> So a looong weekend. >>> >> > >>> >> > ;-) >>> >> > >>> >> > OK, I have a new sedat.2011.04.21a branch in the -rcu git tree: >>> >> > >>> >> > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu.git >>> >> > >>> >> > This is against 2.6.39-rc3, as before. (Yes, I do need to rebase to >>> >> > 2.6.39-rc4, but didn't want to change any more than I had to.) >>> >> > >>> >> > I also have an updated script, which is attached. The output is similar >>> >> > to the earlier one, and it operated is pretty much the same way. >>> >> > >>> >> > Have a great weekend, and I look forward to seeing what shows up on >>> >> > this round. I confess to still being quite puzzled! >>> >> > >>> >> > Thanx, Paul >>> >> > >>> >> >>> >> Here are the results of the Sedat's vote (European song contest :-)). >>> > >>> > ;-) >>> > >>> > Very strange. RCU has told the per-CPU kthread that it needs to get >>> > to work, but this kthread is still waiting from RCU's viewpoint. >>> > Yet the "ps" command believes that this kthread is in fact runnable >>> > at SCHED_FIFO priority 1. >>> > >>> > I can tell that this one will require some thought... And more >>> > diagnostics... >>> > >>> > Thanx, Paul >>> > >>> >>> "We are with you in spirit." >>> >>> ( Level XX from Hybris shooter-game on Amiga (1989) ) >> >> OK, I added a few more diagnostics: sedat.2011.04.23a in -rcu: >> >> git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu.git >> >> When you get a chance, could you please give it a try? >> >> Thanx, Paul >> > > As soon as I can clone/pull from new GIT repo/branch. > Currently, I don't see it only, but kernel-mirrors are sometimes slow. > > I will report later. > > - Sedat - > Hi Paul, I have seen CONFIG_DEBUG_OBJECTS_RCU_HEAD mentionned in the commits, so I enabled it here together with CONFIG_DEBUG_OBJECTS=y. Hope this is OK. Am I missing other useful (*DEBUG_OBJECT*) kernel options? - Sedat - P.S.: Enabled CONFIG_DEBUG_OBJECTS=y and CONFIG_DEBUG_OBJECTS_RCU_HEAD=y (and some more) # diff -uprN for-paulk-3/config-2.6.39-rc3-preempt-rcu-sedat.2011.04.21a+ for-paulk-4/config-2.6.39-rc3-preempt-rcu-sedat.2011.04.23a+ --- for-paulk-3/config-2.6.39-rc3-preempt-rcu-sedat.2011.04.21a+ 2011-04-22 10:25:42.000000000 +0200 +++ for-paulk-4/config-2.6.39-rc3-preempt-rcu-sedat.2011.04.23a+ 2011-04-24 00:35:37.000000000 +0200 @@ -1,7 +1,7 @@ # # Automatically generated make config: don't edit # Linux/i386 2.6.39-rc3 Kernel Configuration -# Fri Apr 22 09:54:37 2011 +# Sat Apr 23 23:58:52 2011 # # CONFIG_64BIT is not set CONFIG_X86_32=y @@ -3065,7 +3065,14 @@ CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE=0 CONFIG_SCHED_DEBUG=y # CONFIG_SCHEDSTATS is not set CONFIG_TIMER_STATS=y -# CONFIG_DEBUG_OBJECTS is not set +CONFIG_DEBUG_OBJECTS=y +# CONFIG_DEBUG_OBJECTS_SELFTEST is not set +# CONFIG_DEBUG_OBJECTS_FREE is not set +CONFIG_DEBUG_OBJECTS_TIMERS=y +# CONFIG_DEBUG_OBJECTS_WORK is not set +CONFIG_DEBUG_OBJECTS_RCU_HEAD=y +CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER=y +CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT=1 # CONFIG_SLUB_DEBUG_ON is not set # CONFIG_SLUB_STATS is not set # CONFIG_DEBUG_KMEMLEAK is not set Download attachment "for-paulk-4.tar.xz" of type "application/octet-stream" (23120 bytes) Download attachment "for-paulk-4.tar.xz.sha256sum" of type "application/octet-stream" (85 bytes)
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