From: Ralf Baechle <ralf@linux-mips.org>
To: maksim.rayskiy@gmail.com
Cc: linux-mips@linux-mips.org, Maksim Rayskiy <mrayskiy@broadcom.com>
Subject: Re: [PATCH] MIPS: clear idle task mm pointer when hotplugging cpu
Date: Wed, 9 Feb 2011 13:02:09 +0100 [thread overview]
Message-ID: <20110209120209.GA21796@linux-mips.org> (raw)
In-Reply-To: <1297210687-14589-1-git-send-email-maksim.rayskiy@gmail.com>
On Tue, Feb 08, 2011 at 04:18:07PM -0800, maksim.rayskiy@gmail.com wrote:
> If kernel starts with maxcpus= option which does not bring all
> available cpus online at boot time, idle tasks for offline cpus
> are not created. If later offline cpus are hotplugged through sysfs,
> __cpu_up is called in the context of the user task, and fork_idle
> copies its non-zero mm pointer. This causes BUG() in per_cpu_trap_init.
>
> To avoid this, release mm for idle task and reset the pointer after
> fork_idle().
Nice catch, applied.
x86 avoid this problem by forking the idle threads in a worker thread which
also avoids other potencial issues; we probably should take the same
path.
Ralf
prev parent reply other threads:[~2011-02-09 12:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-09 0:18 [PATCH] MIPS: clear idle task mm pointer when hotplugging cpu maksim.rayskiy
2011-02-09 12:02 ` Ralf Baechle [this message]
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=20110209120209.GA21796@linux-mips.org \
--to=ralf@linux-mips.org \
--cc=linux-mips@linux-mips.org \
--cc=maksim.rayskiy@gmail.com \
--cc=mrayskiy@broadcom.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.