From: "Paul E. McKenney" <paulmck@kernel.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Brian Foster <bfoster@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-xfs@vger.kernel.org, Ian Kent <raven@themaw.net>,
rcu@vger.kernel.org
Subject: Re: [PATCH] xfs: require an rcu grace period before inode recycle
Date: Wed, 9 Feb 2022 21:45:44 -0800 [thread overview]
Message-ID: <20220210054544.GI4285@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20220210040917.GN59729@dread.disaster.area>
On Thu, Feb 10, 2022 at 03:09:17PM +1100, Dave Chinner wrote:
> On Mon, Feb 07, 2022 at 08:36:21AM -0800, Paul E. McKenney wrote:
> > On Mon, Feb 07, 2022 at 08:30:03AM -0500, Brian Foster wrote:
> > Another approach is to use SLAB_TYPESAFE_BY_RCU. This allows immediate
> > reuse of freed memory, but also requires pointer traversals to the memory
> > to do a revalidation operation. (Sorry, no free lunch here!)
>
> Can't do that with inodes - newly allocated/reused inodes have to go
> through inode_init_always() which is the very function that causes
> the problems we have now with path-walk tripping over inodes in an
> intermediate re-initialised state because we recycled it inside a
> RCU grace period.
So not just no free lunch, but this is also not a lunch that is consistent
with the code's dietary restrictions.
From what you said earlier in this thread, I am guessing that you have
some other fix in mind.
Thanx, Paul
next prev parent reply other threads:[~2022-02-10 5:45 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-21 14:24 [PATCH] xfs: require an rcu grace period before inode recycle Brian Foster
2022-01-21 17:26 ` Darrick J. Wong
2022-01-21 18:33 ` Brian Foster
2022-01-22 5:30 ` Paul E. McKenney
2022-01-22 16:55 ` Paul E. McKenney
2022-01-24 15:12 ` Brian Foster
2022-01-24 16:40 ` Paul E. McKenney
2022-01-23 22:43 ` Dave Chinner
2022-01-24 15:06 ` Brian Foster
2022-01-24 15:02 ` Brian Foster
2022-01-24 22:08 ` Dave Chinner
2022-01-24 23:29 ` Brian Foster
2022-01-25 0:31 ` Dave Chinner
2022-01-25 14:40 ` Paul E. McKenney
2022-01-25 22:36 ` Dave Chinner
2022-01-26 5:29 ` Paul E. McKenney
2022-01-26 13:21 ` Brian Foster
2022-01-25 18:30 ` Brian Foster
2022-01-25 20:07 ` Brian Foster
2022-01-25 22:45 ` Dave Chinner
2022-01-27 4:19 ` Al Viro
2022-01-27 5:26 ` Dave Chinner
2022-01-27 19:01 ` Brian Foster
2022-01-27 22:18 ` Dave Chinner
2022-01-28 14:11 ` Brian Foster
2022-01-28 23:53 ` Dave Chinner
2022-01-31 13:28 ` Brian Foster
2022-01-28 21:39 ` Paul E. McKenney
2022-01-31 13:22 ` Brian Foster
2022-02-01 22:00 ` Paul E. McKenney
2022-02-03 18:49 ` Paul E. McKenney
2022-02-07 13:30 ` Brian Foster
2022-02-07 16:36 ` Paul E. McKenney
2022-02-10 4:09 ` Dave Chinner
2022-02-10 5:45 ` Paul E. McKenney [this message]
2022-02-10 20:47 ` Brian Foster
2022-01-25 8:16 ` [xfs] a7f4e88080: aim7.jobs-per-min -62.2% regression kernel test robot
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