From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] treewide: fix memory corruptions when TASK_COMM_LEN != 16
Date: Tue, 31 Jan 2012 19:01:09 -0800 [thread overview]
Message-ID: <20120131190109.b53347fd.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.LNX.2.01.1202010257240.29848@frira.zrqbmnf.qr>
On Wed, 1 Feb 2012 03:15:50 +0100 (CET) Jan Engelhardt <jengelh@medozas.de> wrote:
>
> On Wednesday 2012-02-01 02:49, Andrew Morton wrote:
> >>
> >> Did my patch not change the existing code sites using ->comm
> >> to always copy at most min(userbufsize aka 16, sizeof(t->comm)) bytes,
> >> thereby keeping the promise to userspace while at the same time
> >> making TASK_COMM_LEN's value freely choosable?
> >
> >That change is pretty pointless as long as we don't provide APIs to let
> >userspace access the expanded size. And I've explained why we cannot
> >alter the existing APIs.
>
> Ah yes, indeed. My reason for augmenting the size of t->comm was so
> that `ps afx` could show a more complete name of certain kernel
> threads' names. In this case, the kernel delivers the name via
> procfs via seq_printf("%s, t->comm),
Where does procfs do this?
> as do a few debug statements
> in the fashion of pr_debug("%s/%u ate my CPU", t->comm, t->pid).
> So maybe it was not /completely/ pointless.
I agree that the 16-char thing is irritatingly small. But if we were
to increase it and to then utilise that increase, those userspace apps
which are still using the legacy prctl(PR_GET_NAME) would produce
pretty bad output. Instead of "migration/0" and "migration/1" you'd
get "migration_threa" and "migration_threa". And "flush-8:32" would
maddeningly become "flusher_thread-".
I suppose that would help motivate people to update their tools ;)
next prev parent reply other threads:[~2012-02-01 3:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-21 22:09 Jan Engelhardt
2012-01-21 22:09 ` [PATCH 2/2] treewide: avoid truncation of process name Jan Engelhardt
2012-01-24 21:54 ` [PATCH 1/2] treewide: fix memory corruptions when TASK_COMM_LEN != 16 Andrew Morton
2012-02-01 1:15 ` Jan Engelhardt
2012-02-01 1:23 ` Andrew Morton
2012-02-01 1:35 ` Jan Engelhardt
2012-02-01 1:49 ` Andrew Morton
2012-02-01 2:15 ` Jan Engelhardt
2012-02-01 3:01 ` Andrew Morton [this message]
2012-02-22 12:48 ` Jan Engelhardt
2012-02-22 20:58 ` Andrew Morton
2012-02-23 9:09 ` Jan Engelhardt
2012-02-23 9:57 ` Andrew Morton
2012-02-23 11:19 ` Jan Engelhardt
2012-02-23 17:30 ` Andrew Morton
2012-02-23 21:59 ` Jan Engelhardt
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