Hi, Paul: the enclosed is the log trigger the 120s hung_task_panic without other debug patches, the hung task is blocked at __wait_rcu_gp, it means the rcu_cpu_stall can't detect the scenario: echo 1 > /proc/sys/kernel/panic_on_rcu_stall echo 7 > /sys/module/rcupdate/parameters/rcu_cpu_stall_timeout
-----Original Message-----
From: Paul E. McKenney <paul...@linux.ibm.com>
Sent: Monday, December 3, 2018 9:57 PM
To: He, Bo <bo...@intel.com>
Cc: Steven Rostedt <rost...@goodmis.org>; linux-kernel@vger.kernel.org;
j...@joshtriplett.org; mathieu.desnoy...@efficios.com; jiangshan...@gmail.com;
Zhang, Jun <jun.zh...@intel.com>; Xiao, Jin <jin.x...@intel.com>; Zhang, Yanmin
<yanmin.zh...@intel.com>
Subject: Re: rcu_preempt caused oom
On Mon, Dec 03, 2018 at 07:44:03AM +0000, He, Bo wrote:
> Thanks, we have run the test for the whole weekend and not reproduce the
> issue, so we confirm the CONFIG_RCU_BOOST can fix the issue.
Very good, that is encouraging. Perhaps I should think about making
CONFIG_RCU_BOOST=y the default for CONFIG_PREEMPT in mainline, at least for
architectures for which rt_mutexes are implemented.
> We have enabled the rcupdate.rcu_cpu_stall_timeout=7 and also set panic on
> rcu stall and will see if we can see the panic, will keep you posed with the
> test results.
> echo 1 > /proc/sys/kernel/panic_on_rcu_stall
Looking forward to seeing what is going on! Of course, to reproduce, you will
need to again build with CONFIG_RCU_BOOST=n.
Thanx, Paul
> -----Original Message-----
> From: Paul E. McKenney <paul...@linux.ibm.com>
> Sent: Saturday, December 1, 2018 12:49 AM
> To: He, Bo <bo...@intel.com>
> Cc: Steven Rostedt <rost...@goodmis.org>;
> linux-kernel@vger.kernel.org; j...@joshtriplett.org;
> mathieu.desnoy...@efficios.com; jiangshan...@gmail.com; Zhang, Jun
> <jun.zh...@intel.com>; Xiao, Jin <jin.x...@intel.com>; Zhang, Yanmin
> <yanmin.zh...@intel.com>
> Subject: Re: rcu_preempt caused oom
>
> On Fri, Nov 30, 2018 at 03:18:58PM +0000, He, Bo wrote:
> > Here is the kernel cmdline:
>
> Thank you!
>
> > Kernel command line: androidboot.acpio_idx=0
> > androidboot.bootloader=efiwrapper-02_03-userdebug_kernelflinger-06_0
> > 3- userdebug androidboot.diskbus=00.0
> > androidboot.verifiedbootstate=green
> > androidboot.bootreason=power-on androidboot.serialno=R1J56L6006a7bb
> > g_ffs.iSerialNumber=R1J56L6006a7bb no_timer_check noxsaves
> > reboot_panic=p,w i915.hpd_sense_invert=0x7 mem=2G nokaslr nopti
> > ftrace_dump_on_oops trace_buf_size=1024K intel_iommu=off gpt
> > loglevel=4 androidboot.hardware=gordon_peak
> > firmware_class.path=/vendor/firmware relative_sleep_states=1
> > enforcing=0 androidboot.selinux=permissive cpu_init_udelay=10
> > androidboot.android_dt_dir=/sys/bus/platform/devices/ANDR0001:00/pro
> > pe rties/android/ pstore.backend=ramoops memmap=0x1400000$0x50000000
> > ramoops.mem_address=0x50000000 ramoops.mem_size=0x1400000
> > ramoops.record_size=0x4000 ramoops.console_size=0x1000000
> > ramoops.ftrace_size=0x10000 ramoops.dump_oops=1 vga=current
> > i915.modeset=1 drm.atomic=1 i915.nuclear_pageflip=1
> > drm.vblankoffdelay=
>
> And no sign of any suppression of RCU CPU stall warnings. Hmmm...
> It does take more than 21 seconds to OOM? Or do things happen faster than
> that? If they do happen faster than that, then on approach would be to add
> something like this to the kernel command line:
>
> rcupdate.rcu_cpu_stall_timeout=7
>
> This would set the stall timeout to seven seconds. Note that timeouts less
> than three seconds are silently interpreted as three seconds.
>
> Thanx, Paul
>
> > -----Original Message-----
> > From: Steven Rostedt <rost...@goodmis.org>
> > Sent: Friday, November 30, 2018 11:17 PM
> > To: Paul E. McKenney <paul...@linux.ibm.com>
> > Cc: He, Bo <bo...@intel.com>; linux-kernel@vger.kernel.org;
> > j...@joshtriplett.org; mathieu.desnoy...@efficios.com;
> > jiangshan...@gmail.com; Zhang, Jun <jun.zh...@intel.com>; Xiao, Jin
> > <jin.x...@intel.com>; Zhang, Yanmin <yanmin.zh...@intel.com>
> > Subject: Re: rcu_preempt caused oom
> >
> > On Fri, 30 Nov 2018 06:43:17 -0800
> > "Paul E. McKenney" <paul...@linux.ibm.com> wrote:
> >
> > > Could you please send me your list of kernel boot parameters?
> > > They usually appear near the start of your console output.
> >
> > Or just: cat /proc/cmdline
> >
> > -- Steve
> >
>
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