linux-kernel - Re: + convert-cpu-hotplug-notifiers-to-use-raw_notifier-instead-of-blocking

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Date:	Fri, 13 Oct 2006 17:19:16 +0200
From:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>
To:	akpm@...l.org
CC:	neilb@...e.de, michal.k.k.piotrowski@...il.com,
	rusty@...tcorp.com.au, "LKML" <linux-kernel@...r.kernel.org>
Subject: Re: + convert-cpu-hotplug-notifiers-to-use-raw_notifier-instead-of-blocking_notifier.patch
 added to -mm tree

Hi,

akpm@...l.org wrote:
> The patch titled
> 
>      Convert cpu hotplug notifiers to use raw_notifier instead of blocking_notifier
> 
> has been added to the -mm tree.  Its filename is
> 
>      convert-cpu-hotplug-notifiers-to-use-raw_notifier-instead-of-blocking_notifier.patch
> 
> See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
> out what to do about this
> 
> ------------------------------------------------------
> Subject: Convert cpu hotplug notifiers to use raw_notifier instead of blocking_notifier
> From: Neil Brown <neilb@...e.de>
> 
> The use of blocking notifier by _cpu_up and _cpu_down in cpu.c has two
> problem.
> 
> 1/ An interaction with the workqueue notifier causes lockdep to spit a
>    warning.
> 
> 2/ A notifier could conceivable be added or removed while _cpu_up or
>    _cpu_down are in process.  As each notifier is called twice (prepare
>    then commit/abort) this could be unhealthy.
> 
> To fix to we simply take cpu_add_remove_lock while adding or removing
> notifiers to/from the list.
> 
> This makes the 'blocking' usage unnecessary as all accesses to cpu_chain
> are now protected by cpu_add_remove_lock.  So change "blocking" to "raw" in
> all relevant places.  This fixes 1.
> 

There is something really wrong with this patch (or my hardware).

echo shutdown > /sys/power/disk; echo disk > /sys/power/state
works fine for me on 2.6.19-rc1-g8770c018.

On 2.6.19-rc1-mm1 +
convert-cpu-hotplug-notifiers-to-use-raw_notifier-instead-of-blocking_notifier.patch
+ Neil's avoid_lockdep_warning_in_md.patch
(http://www.ussg.iu.edu/hypermail/linux/kernel/0610.1/0642.html)
I get a lot of "end_request: I/O error, dev sda, sector 31834343" messages.

I checked sda with badblocks and everything seems to be fine
/sbin/badblocks -o /root/sda.badblocks -v /dev/sda
Sprawdzanie bloków od 0 do 156290904
Poszukiwanie wadliwych bloków (tylko odczyt): done
Przebieg zakończony, znaleziono 0 wadliwych bloków.
(/root/sda.badblocks is empty)

BTW. sda is a new Seagate SATA II HDD atached to ICH5 (SATA I) controller.

Regards,
Michal

-- 
Michal K. K. Piotrowski
LTG - Linux Testers Group
(http://www.stardust.webpages.pl/ltg/)
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