Re: [PATCH] Busy inodes after unmount, be more verbose in generic_shutdown_super

From: Balbir Singh <balbir@in.ibm.com>
To: Kirill Korotaev <dev@sw.ru>
Cc: Neil Brown <neilb@suse.de>, Balbir Singh <bsingharora@gmail.com>,
	linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
	Olaf Hering <olh@suse.de>, Jan Blunck <jblunck@suse.de>,
	Kirill Korotaev <dev@openvz.org>, Al Viro <viro@ftp.linux.org.uk>
Subject: Re: [PATCH] Busy inodes after unmount, be more verbose in generic_shutdown_super
Date: Tue, 7 Mar 2006 16:35:53 +0530	[thread overview]
Message-ID: <20060307110553.GA15796@in.ibm.com> (raw)
In-Reply-To: <440D3475.4040603@sw.ru>

> >Given that background, I thought our main concern was with respect to
> >unmount. The race was between shrink_dcache_parent() (called from unmount)
> >and shrink_dcache_memory() (called from the allocator), hence the fix
> >for the race condition.
> Partial fix doesn't make much sense from my point of view.
>

IMHO, It was not a partial fix. slab_drop() addition changed the assumptions
used by this fix 

> >I just noticied that 2.6.16-rc* now seems to have drop_slab() where
> >PF_MEMALLOC is not set. So, we can still race with my fix if there
> >if /proc/sys/vm/drop_caches is written to and unmount is done in parallel.
> >
> >A simple hack would be to set PF_MEMALLOC in drop_slab(), but I do not
> >think it is a good idea.
> Yeah, playing with PF_MEMALLOC can be not so good idea :/
> And as it doesn't help in other cases it looks unpromising...

Yes, agreed.

> 
> >>>Have you had any other feedback on this?
> >>here it is :)
> >Thanks for your detailed feedback
> Sorry, that I did it too late :/
> 

No problem

> Thanks,
> Kirill
> 

Balbir