From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [patch] rt, hotplug: Use set_cpus_allowed_ptr() in sync_unplug_thread()
Date: Thu, 9 Apr 2015 16:05:12 +0200 [thread overview]
Message-ID: <20150409140512.GB2416@linutronix.de> (raw)
In-Reply-To: <1427181289.3316.27.camel@gmail.com>
* Mike Galbraith | 2015-03-24 08:14:49 [+0100]:
>do_set_cpus_allowed() is not safe vs ->sched_class change.
>
>crash> bt
>PID: 11676 TASK: ffff88026f979da0 CPU: 22 COMMAND: "sync_unplug/22"
> #0 [ffff880274d25bc8] machine_kexec at ffffffff8103b41c
> #1 [ffff880274d25c18] crash_kexec at ffffffff810d881a
> #2 [ffff880274d25cd8] oops_end at ffffffff81525818
> #3 [ffff880274d25cf8] do_invalid_op at ffffffff81003096
> #4 [ffff880274d25d90] invalid_op at ffffffff8152d3de
> [exception RIP: set_cpus_allowed_rt+18]
> RIP: ffffffff8109e012 RSP: ffff880274d25e48 RFLAGS: 00010202
> RAX: ffffffff8109e000 RBX: ffff88026f979da0 RCX: ffff8802770cb6e8
> RDX: 0000000000000000 RSI: ffffffff81add700 RDI: ffff88026f979da0
> RBP: ffff880274d25e78 R8: ffffffff816112e0 R9: 0000000000000001
> R10: 0000000000000001 R11: 0000000000011940 R12: ffff88026f979da0
> R13: ffff8802770cb6d0 R14: ffff880274d25fd8 R15: 0000000000000000
> ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
> #5 [ffff880274d25e60] do_set_cpus_allowed at ffffffff8108e65f
> #6 [ffff880274d25e80] sync_unplug_thread at ffffffff81058c08
> #7 [ffff880274d25ed8] kthread at ffffffff8107cad6
> #8 [ffff880274d25f50] ret_from_fork at ffffffff8152bbbc
>crash> task_struct ffff88026f979da0 | grep class
> sched_class = 0xffffffff816111e0 <fair_sched_class+64>,
Is this a one-time thing or can you reproduce this?
What happen here? I doubt p vanished. +18 is mostlikely the
"migrate_disabled_updated()" check.
I doubt p->sched_class->set_cpus_allowed or p->sched_class vanish
between testing for it and invoking it, or did it?
>Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
>Cc: stable-rt@vger.kernel.org
>---
> kernel/cpu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>--- a/kernel/cpu.c
>+++ b/kernel/cpu.c
>@@ -265,7 +265,7 @@ static int sync_unplug_thread(void *data
> * we don't want any more work on this CPU.
> */
> current->flags &= ~PF_NO_SETAFFINITY;
>- do_set_cpus_allowed(current, cpu_present_mask);
>+ set_cpus_allowed_ptr(current, cpu_present_mask);
> migrate_me();
> return 0;
> }
Sebastian
next prev parent reply other threads:[~2015-04-09 14:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-24 7:14 [patch] rt, hotplug: Use set_cpus_allowed_ptr() in sync_unplug_thread() Mike Galbraith
2015-04-09 14:05 ` Sebastian Andrzej Siewior [this message]
2015-04-09 14:23 ` Mike Galbraith
2015-04-09 14:54 ` Sebastian Andrzej Siewior
2015-04-09 17:40 ` Mike Galbraith
2015-04-10 14:00 ` Sebastian Andrzej Siewior
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