From: Andrew Morton <akpm@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: John Stultz <john.stultz@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
Joe Perches <joe@perches.com>,
Michal Nazarewicz <mina86@mina86.com>,
Andy Whitcroft <apw@canonical.com>,
Jiri Slaby <jirislaby@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
David Rientjes <rientjes@google.com>,
Dave Hansen <dave@linux.vnet.ibm.com>,
linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/4] v6 Improve task->comm locking situation
Date: Wed, 18 May 2011 00:05:27 -0700 [thread overview]
Message-ID: <20110518000527.bcced636.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110518062554.GB2945@elte.hu>
On Wed, 18 May 2011 08:25:54 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> " Hey, this looks a bit racy and 'top' very rarely, on rare workloads that
> play with ->comm[], might display a weird reading task name for a second,
> amongst the many other temporarily nonsensical statistical things it
> already prints every now and then. "
Well we should at least make sure that `top' won't run off the end of
comm[] and go oops. I think that's guaranteed by the fact(s) that
init_tasks's comm[15] is zero and is always copied-by-value across
fork and can never be overwritten in any task_struct.
But I didn't check that.
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: John Stultz <john.stultz@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
Joe Perches <joe@perches.com>,
Michal Nazarewicz <mina86@mina86.com>,
Andy Whitcroft <apw@canonical.com>,
Jiri Slaby <jirislaby@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
David Rientjes <rientjes@google.com>,
Dave Hansen <dave@linux.vnet.ibm.com>,
linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/4] v6 Improve task->comm locking situation
Date: Wed, 18 May 2011 00:05:27 -0700 [thread overview]
Message-ID: <20110518000527.bcced636.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110518062554.GB2945@elte.hu>
On Wed, 18 May 2011 08:25:54 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> " Hey, this looks a bit racy and 'top' very rarely, on rare workloads that
> play with ->comm[], might display a weird reading task name for a second,
> amongst the many other temporarily nonsensical statistical things it
> already prints every now and then. "
Well we should at least make sure that `top' won't run off the end of
comm[] and go oops. I think that's guaranteed by the fact(s) that
init_tasks's comm[15] is zero and is always copied-by-value across
fork and can never be overwritten in any task_struct.
But I didn't check that.
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next prev parent reply other threads:[~2011-05-18 7:06 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-18 1:41 [PATCH 0/4] v6 Improve task->comm locking situation John Stultz
2011-05-18 1:41 ` John Stultz
2011-05-18 1:41 ` [PATCH 1/4] comm: Introduce comm_lock spinlock to protect task->comm access John Stultz
2011-05-18 1:41 ` John Stultz
2011-05-18 2:01 ` KOSAKI Motohiro
2011-05-18 2:01 ` KOSAKI Motohiro
2011-05-18 4:11 ` John Stultz
2011-05-18 4:11 ` John Stultz
2011-05-18 5:06 ` KOSAKI Motohiro
2011-05-18 5:06 ` KOSAKI Motohiro
2011-05-18 1:41 ` [PATCH 2/4] comm: Add lock-free task->comm accessor John Stultz
2011-05-18 1:41 ` John Stultz
2011-05-18 1:41 ` [PATCH 3/4] printk: Add %ptc to safely print a task's comm John Stultz
2011-05-18 1:41 ` John Stultz
2011-05-18 1:41 ` [PATCH 4/4] checkpatch.pl: Add check for task comm references John Stultz
2011-05-18 1:41 ` John Stultz
2011-05-18 6:25 ` [PATCH 0/4] v6 Improve task->comm locking situation Ingo Molnar
2011-05-18 6:25 ` Ingo Molnar
2011-05-18 7:05 ` Andrew Morton [this message]
2011-05-18 7:05 ` Andrew Morton
2011-05-18 7:58 ` Ingo Molnar
2011-05-18 7:58 ` Ingo Molnar
2011-05-18 19:03 ` John Stultz
2011-05-18 19:03 ` John Stultz
2011-05-18 19:33 ` Andrew Morton
2011-05-18 19:33 ` Andrew Morton
2011-05-18 19:48 ` Ingo Molnar
2011-05-18 19:48 ` Ingo Molnar
2011-05-18 19:56 ` Andrew Morton
2011-05-18 19:56 ` Andrew Morton
2011-05-18 20:48 ` Ingo Molnar
2011-05-18 20:48 ` Ingo Molnar
2011-05-18 19:58 ` Linus Torvalds
2011-05-18 19:58 ` Linus Torvalds
2011-05-20 10:41 ` KOSAKI Motohiro
2011-05-20 10:41 ` KOSAKI Motohiro
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