From: Matthew Wilcox <matthew@wil.cx>
To: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"George G. Davis" <gdavis@mvista.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFC, PATCH] locks: remove posix deadlock detection
Date: Sun, 28 Oct 2007 12:27:32 -0600 [thread overview]
Message-ID: <20071028182732.GK27248@parisc-linux.org> (raw)
In-Reply-To: <20071028174321.GB16905@fieldses.org>
On Sun, Oct 28, 2007 at 01:43:21PM -0400, J. Bruce Fields wrote:
> We currently attempt to return -EDEALK to blocking fcntl() file locking
> requests that would create a cycle in the graph of tasks waiting on
> locks.
>
> This is inefficient: in the general case it requires us determining
> whether we're adding a cycle to an arbitrary directed acyclic graph.
> And this calculation has to be performed while holding a lock (currently
> the BKL) that prevents that graph from changing.
>
> It has historically been a source of bugs; most recently it was noticed
> that it could loop indefinitely while holding the BKL.
It can also return -EDEADLK spuriously. So yeah, just kill it.
--
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
next prev parent reply other threads:[~2007-10-28 18:27 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20071017185157.GC3785@mvista.com>
[not found] ` <20071018185759.GU3785@mvista.com>
[not found] ` <20071026170750.GC13033@fieldses.org>
[not found] ` <20071026224707.GO13033@fieldses.org>
2007-10-28 17:31 ` [PATCH] locks: fix possible infinite loop in posix deadlock detection J. Bruce Fields
2007-10-28 17:43 ` [RFC, PATCH] locks: remove " J. Bruce Fields
2007-10-28 18:27 ` Matthew Wilcox [this message]
2007-10-28 18:40 ` Alan Cox
2007-10-28 20:11 ` Matthew Wilcox
2007-10-28 21:38 ` Alan Cox
2007-10-28 21:45 ` Jiri Kosina
2007-10-28 23:38 ` Matthew Wilcox
2007-10-28 23:44 ` Alan Cox
2007-10-28 21:50 ` Trond Myklebust
2007-10-28 22:41 ` Matthew Wilcox
2007-10-28 22:48 ` Alan Cox
2007-10-28 22:55 ` Matthew Wilcox
2007-10-28 23:38 ` Alan Cox
2007-10-29 2:29 ` J. Bruce Fields
2007-10-29 8:08 ` Alan Cox
2007-10-29 9:15 ` Jiri Kosina
2007-10-30 15:35 ` J. Bruce Fields
2007-10-28 22:55 ` Jiri Kosina
2007-10-28 23:31 ` Matthew Wilcox
2007-10-29 9:11 ` Jiri Kosina
2007-10-29 2:10 ` J. Bruce Fields
2007-10-29 3:26 ` Trond Myklebust
2007-10-29 1:13 ` J. Bruce Fields
2007-10-29 8:06 ` Alan Cox
2007-10-30 15:51 ` J. Bruce Fields
2007-10-30 15:20 ` [PATCH, RESEND] locks: fix possible infinite loop in " J. Bruce Fields
2007-10-30 15:35 ` Alan Cox
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=20071028182732.GK27248@parisc-linux.org \
--to=matthew@wil.cx \
--cc=akpm@linux-foundation.org \
--cc=bfields@fieldses.org \
--cc=gdavis@mvista.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).