From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: on CONFIG_MM_OWNER=y, kernel panic is possible.
Date: Tue, 06 May 2008 11:18:05 +0530 [thread overview]
Message-ID: <481FF115.8030503@linux.vnet.ibm.com> (raw)
In-Reply-To: <20080506142255.AC5D.KOSAKI.MOTOHIRO@jp.fujitsu.com>
KOSAKI Motohiro wrote:
> on CONFIG_MM_OWNER=y (that is automatically turned on by mem-cgroup),
> kernel panic is possible by following scenario in mm_update_next_owner().
>
> 1. mm_update_next_owner() is called.
> 2. found caller task in do_each_thread() loop.
> 3. thus, BUG_ON(c == p) is true, it become kernel panic.
>
> end up, We should left out current task.
>
>
That is not possible. If you look at where mm_update_next_owner() is called
from, we call it from
exit_mm() and exec_mmap()
In both cases, we ensure that the task's mm has changed (to NULL and the new mm
respectively), before we call mm_update_next_owner(), hence c->mm can never be
equal to p->mm.
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2008-05-06 5:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-06 5:40 on CONFIG_MM_OWNER=y, kernel panic is possible KOSAKI Motohiro
2008-05-06 5:48 ` Balbir Singh [this message]
2008-05-06 6:03 ` KOSAKI Motohiro
2008-05-06 6:18 ` KOSAKI Motohiro
2008-05-06 6:28 ` Balbir Singh
2008-05-06 6:43 ` KOSAKI Motohiro
2008-05-07 3:37 ` Paul Menage
2008-05-07 23:55 ` [PATCH] on CONFIG_MM_OWNER=y, kernel panic is possible. take2 KOSAKI Motohiro
2008-05-08 13:53 ` Balbir Singh
2008-05-06 6:32 ` on CONFIG_MM_OWNER=y, kernel panic is possible Balbir Singh
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=481FF115.8030503@linux.vnet.ibm.com \
--to=balbir@linux.vnet.ibm.com \
--cc=Lee.Schermerhorn@hp.com \
--cc=akpm@linux-foundation.org \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).