Messages in this thread | | | From | "Liu, Chuansheng" <> | Subject | RE: [PATCH] Fix the race between smp_call_function and CPU booting | Date | Fri, 23 Mar 2012 12:06:22 +0000 |
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Sorry to not see your scripts in details.
If so, I has something wrong about merging your change of select_fallback_rq()? I am using 3.0.8.
I indeed see the warning even with the change of select_fallback_rq().
> -----Original Message----- > From: Peter Zijlstra [mailto:peterz@infradead.org] > Sent: Friday, March 23, 2012 8:02 PM > To: Liu, Chuansheng > Cc: linux-kernel@vger.kernel.org; Yanmin Zhang; tglx@linutronix.de; Srivatsa S. > Bhat > Subject: RE: [PATCH] Fix the race between smp_call_function and CPU booting > > On Fri, 2012-03-23 at 11:32 +0000, Liu, Chuansheng wrote: > > In fact, I started two scripts running: > > 1/ One script: > > echo 0 > /sys/devices/system/cpuX/online echo 1 > > > /sys/devices/system/cpuX/online Rerunning the above commands in loop > > > > 2/Another script: > > echo 1 > /debug/smp_call_test > > usleep 50000 > > Rerunning the above command in loop > > > > This race issue can be easy to be reproduced in several minutes; For > > simplify your test as mine(just two CPUs), you can set other > > non-booting CPUs as offline at first and just leave one non-booting CPU. > > So this is exactly what I did and it ran for 30+ minutes without fail. I found I > forgot to log the serial output so I just re-ran this to make sure. 10+ minutes > and not a single WARN in the console output. > > If I pop my change to select_fallback_rq() I can indeed trigger this: > > ------------[ cut here ]------------ > WARNING: at /usr/src/linux-2.6/arch/x86/kernel/smp.c:120 > native_smp_send_reschedule+0x5b/0x60() > Hardware name: X8DTN > Modules linked in: [last unloaded: scsi_wait_scan] > Pid: 1542, comm: abrtd Not tainted 3.3.0-01725-gd6eb054-dirty #63 Call Trace: > <IRQ> [<ffffffff810775df>] warn_slowpath_common+0x7f/0xc0 > [<ffffffff8107763a>] warn_slowpath_null+0x1a/0x20 [<ffffffff8105f79b>] > native_smp_send_reschedule+0x5b/0x60 > [<ffffffff810aa67a>] try_to_wake_up+0x1fa/0x2c0 [<ffffffff810acaec>] ? > sched_slice.isra.38+0x5c/0x90 [<ffffffff810aa795>] > wake_up_process+0x15/0x20 [<ffffffff81085c6e>] process_timeout+0xe/0x10 > [<ffffffff81086cb3>] run_timer_softirq+0x143/0x460 [<ffffffff81384a94>] ? > timerqueue_add+0x74/0xc0 [<ffffffff81085c60>] ? usleep_range+0x50/0x50 > [<ffffffff8107e81d>] __do_softirq+0xbd/0x290 [<ffffffff810c5e64>] ? > clockevents_program_event+0x74/0x100 > [<ffffffff810c72d4>] ? tick_program_event+0x24/0x30 [<ffffffff8194ba4c>] > call_softirq+0x1c/0x30 [<ffffffff810433d5>] do_softirq+0x55/0x90 > [<ffffffff8107ed2e>] irq_exit+0x9e/0xe0 [<ffffffff8194c07e>] > smp_apic_timer_interrupt+0x6e/0x99 > [<ffffffff8194b107>] apic_timer_interrupt+0x67/0x70 <EOI> ---[ end trace > d2b2cbf78c1ddd2e ]--- > > > But let me re-run with the select_fallback_rq() change and let it run > for several hours while I go play outside..
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