From: Al Viro <viro@ZenIV.linux.org.uk>
To: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Simon Kirby <sim@hostway.ca>, Ian Applegate <ia@cloudflare.com>,
Christoph Lameter <cl@gentwo.org>,
Pekka Enberg <penberg@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Chris Mason <chris.mason@fusionio.com>
Subject: Re: Found it! (was Re: [3.10] Oopses in kmem_cache_allocate() via prepare_creds())
Date: Mon, 2 Dec 2013 16:46:01 +0000 [thread overview]
Message-ID: <20131202164601.GF10323@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20131202162755.GB27781@gmail.com>
On Mon, Dec 02, 2013 at 05:27:55PM +0100, Ingo Molnar wrote:
> It's not like there should be many (any?) VFS operations where a pipe
> is used via i_mutex and pipe->mutex in parallel, which would improve
> scalability - so I don't see the scalability advantage. (But I might
> be missing something)
>
> Barring such kind of workload the extra mutex just adds extra
> micro-costs because now two locks have to be taken on
> creation/destruction, plus it adds extra complexity and races.
>
> So unless I'm missing something obvious, another good fix would be to
> just revert pipe->mutex and rely on i_mutex as before?
You are missing the extra shitloads of complexity in ->i_mutex ordering,
and ->i_mutex is already used for too many things...
next prev parent reply other threads:[~2013-12-02 16:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-02 16:00 Found it! (was Re: [3.10] Oopses in kmem_cache_allocate() via prepare_creds()) Linus Torvalds
2013-12-02 16:27 ` Ingo Molnar
2013-12-02 16:46 ` Al Viro [this message]
2013-12-02 17:05 ` Ingo Molnar
2013-12-02 17:06 ` Al Viro
2013-12-03 2:58 ` Linus Torvalds
2013-12-03 4:28 ` Al Viro
2013-12-05 8:12 ` gfs2 deadlock (was Re: Found it) Al Viro
2013-12-05 10:19 ` [Cluster-devel] " Steven Whitehouse
2013-12-05 10:19 ` Steven Whitehouse
2013-12-03 8:52 ` [PATCH] mutexes: Add CONFIG_DEBUG_MUTEX_FASTPATH=y debug variant to debug SMP races Ingo Molnar
2013-12-03 18:10 ` Linus Torvalds
2013-12-04 9:19 ` Simon Kirby
2013-12-04 21:14 ` Linus Torvalds
2013-12-05 8:06 ` Simon Kirby
2013-12-05 6:57 ` Simon Kirby
2013-12-11 15:03 ` Waiman Long
-- strict thread matches above, loose matches on Subject: below --
2025-10-07 4:03 Found it! (was Re: [3.10] Oopses in kmem_cache_allocate() via prepare_creds()) Steven Paul Jobs
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=20131202164601.GF10323@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=chris.mason@fusionio.com \
--cc=cl@gentwo.org \
--cc=ia@cloudflare.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=penberg@kernel.org \
--cc=sim@hostway.ca \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.