linux-ext4 - Re: [BUG] aborted ext4 leads to inifinity loop in balance_dirty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 28 Oct 2011 14:34:31 +0900
From:	Kazuya Mio <k-mio@...jp.nec.com>
To:	Jan Kara <jack@...e.cz>
CC:	ext4 <linux-ext4@...r.kernel.org>, Theodore Tso <tytso@....edu>,
	Andreas Dilger <adilger@...ger.ca>
Subject: Re: [BUG] aborted ext4 leads to inifinity loop in balance_dirty_pages

2011/10/25 22:40, Jan Kara wrote:
>   Please no. Generally this boils down to what do we do with dirty data
> when there's error in writing them out. Currently we just throw them away
> (e.g. in media error case) but I don't think that's a generally good thing
> because e.g. admin may want to copy the data to other working storage or
> so. So I think we should rather keep the data and provide a mechanism for
> userspace to ask kernel to get rid of the data (so that we don't eventually
> run OOM).

I see. I agree with you.

>> Do you have any ideas?
>   So the question is what would you like to achieve. If you just want to
> unblock a thread then a solution would be to make a thread at
> balance_dirty_pages() killable. If generally you want to get rid of dirty
> memory, then I don't have a really good answer but throwing dirty data away
> seems like a bad answer to me.

The problem is that we cannot unmount the corrupted filesystem due to
un-killable dd process. We must bring down the system to resume the service
with no dirty pages. I think it is important for the service continuity
to be able to kill the thread handling in balance_dirty_pages().

Regards,
Kazuya Mio

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html