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Date: Fri, 25 Oct 2013 13:48:57 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Michael wang <wangyun@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Fengguang Wu <fengguang.wu@intel.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched: remove extra put_online_cpus() inside
 sched_setaffinity()
Message-ID: <20131025114857.GB6374@gmail.com>
References: <52673C57.1050607@linux.vnet.ibm.com>
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* Michael wang <wangyun@linux.vnet.ibm.com> wrote:

> commit 6acce3ef84520537f8a09a12c9ddbe814a584dd2
>         sched: Remove get_online_cpus() usage
> 
> has left one extra put_online_cpus() inside sched_setaffinity(), remove it
> to fix the WARN:
> 
> [3165] Watchdog is alive
> [3159] Started watchdog thread 3165
> [   58.695502] ------------[ cut here ]------------
> [   58.697835] WARNING: CPU: 0 PID: 3166 at kernel/cpu.c:84 put_online_cpus+0x43/0x70()
> [   58.702423] Modules linked in:
> [   58.704404] CPU: 0 PID: 3166 Comm: trinity-child0 Not tainted 3.12.0-rc5-01882-gf3db366 #1172
> [   58.708530] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [   58.710992]  0000000000000000 ffff88000acfbe50 ffffffff81a24643 0000000000000000
> [   58.715410]  ffff88000acfbe88 ffffffff810c3e6b ffffffff810c3fef 0000000000000000
> [   58.719826]  0000000000000000 0000000000006ee0 0000000000000ffc ffff88000acfbe98
> [   58.724348] Call Trace:
> [   58.726190]  [<ffffffff81a24643>] dump_stack+0x4d/0x66
> [   58.728531]  [<ffffffff810c3e6b>] warn_slowpath_common+0x7f/0x98
> [   58.731069]  [<ffffffff810c3fef>] ? put_online_cpus+0x43/0x70
> [   58.733664]  [<ffffffff810c3f32>] warn_slowpath_null+0x1a/0x1c
> [   58.736258]  [<ffffffff810c3fef>] put_online_cpus+0x43/0x70
> [   58.738686]  [<ffffffff810efd59>] sched_setaffinity+0x7d/0x1f9
> [   58.741210]  [<ffffffff810efce1>] ? sched_setaffinity+0x5/0x1f9
> [   58.743775]  [<ffffffff81a2f724>] ? _raw_spin_unlock_irq+0x2c/0x3e
> [   58.746417]  [<ffffffff810c7012>] ? do_setitimer+0x194/0x1f5
> [   58.748899]  [<ffffffff810eff37>] SyS_sched_setaffinity+0x62/0x71
> [   58.751481]  [<ffffffff81a373a9>] system_call_fastpath+0x16/0x1b
> [   58.754070] ---[ end trace 034818a1f6f06868 ]---
> [   58.757521] ------------[ cut here ]------------
> 
> CC: Ingo Molnar <mingo@kernel.org>
> CC: Peter Zijlstra <peterz@infradead.org>
> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> Tested-by: Fengguang Wu <fengguang.wu@intel.com>
> Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
> ---
>  kernel/sched/core.c |    1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index c06b8d3..7c61f31 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3716,7 +3716,6 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
>         p = find_process_by_pid(pid);
>         if (!p) {
>                 rcu_read_unlock();
> -               put_online_cpus();
>                 return -ESRCH;
>         }

The patch is whitespace damaged.

Thanks,

	Ingo
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