linux-kernel - Re: [PATCH 2/3] Fix fsync livelock

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:	Sun, 5 Oct 2008 16:07:24 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, agk@...hat.com, mbroz@...hat.com,
	chris@...chsys.com
Subject: Re: [PATCH 2/3] Fix fsync livelock

On Sun, 5 Oct 2008 19:02:57 -0400 (EDT)
Mikulas Patocka <mpatocka@...hat.com> wrote:

> > are you sure?
> > isn't the right fix to just walk the file pages only once?
> 
> It walks the pages only once --- and waits on each on them. But
> because new pages are contantly appearing under it, that "walk only
> once" becomes infinite loop (well, finite, until the whole disk is
> written).

well. fsync() promises that everything that's dirty at the time of the
call will hit the disk. That is not something you can compromise.
The only way out would be is to not allow new dirty during an fsync()...
which is imo even worse.

Submit them all in one go, then wait, should not be TOO bad. Unless a
lot was dirty already, but then you go back to "but it has to go to
disk".


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/