From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Qu Wenruo <quwenruo@cn.fujitsu.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
xfs@oss.sgi.com, linux-mm@kvack.org,
Ingo Molnar <mingo@kernel.org>
Subject: Re: Xfs lockdep warning with for-dave-for-4.6 branch
Date: Wed, 18 May 2016 11:49:52 +0200 [thread overview]
Message-ID: <20160518094952.GB3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160518082538.GE21654@dhcp22.suse.cz>
On Wed, May 18, 2016 at 10:25:39AM +0200, Michal Hocko wrote:
> On Wed 18-05-16 09:20:05, Peter Zijlstra wrote:
> > On Wed, May 18, 2016 at 08:35:49AM +1000, Dave Chinner wrote:
> > > On Tue, May 17, 2016 at 04:49:12PM +0200, Peter Zijlstra wrote:
> [...]
> > > > In any case; would something like this work for you? Its entirely
> > > > untested, but the idea is to mark an entire class to skip reclaim
> > > > validation, instead of marking individual sites.
> > >
> > > Probably would, but it seems like swatting a fly with runaway
> > > train. I'd much prefer a per-site annotation (e.g. as a GFP_ flag)
> > > so that we don't turn off something that will tell us we've made a
> > > mistake while developing new code...
> >
> > Fair enough; if the mm folks don't object to 'wasting' a GFP flag on
> > this the below ought to do I think.
>
> GFP flag space is quite scarse.
There's still 5 or so bits available, and you could always make gfp_t
u64.
> Especially when it would be used only
> for lockdep configurations which are mostly disabled. Why cannot we go
> with an explicit disable/enable API I have proposed?
It has unbounded scope. And in that respect the GFP flag thingy is wider
than I'd like too, it avoids setting the state for all held locks, even
though we'd only like to avoid setting it for one class.
So ideally we'd combine the GFP flag with the previously proposed skip
flag to only avoid marking the one class while keeping everything
working for all other held locks.
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next prev parent reply other threads:[~2016-05-18 9:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-12 5:53 Xfs lockdep warning with for-dave-for-4.6 branch Qu Wenruo
2016-05-12 5:57 ` Darrick J. Wong
2016-05-12 8:03 ` Dave Chinner
2016-05-13 16:03 ` Michal Hocko
2016-05-16 10:41 ` Peter Zijlstra
2016-05-16 13:05 ` Michal Hocko
2016-05-16 13:25 ` Peter Zijlstra
2016-05-16 23:10 ` Dave Chinner
2016-05-17 14:49 ` Peter Zijlstra
2016-05-17 22:35 ` Dave Chinner
2016-05-18 7:20 ` Peter Zijlstra
2016-05-18 8:25 ` Michal Hocko
2016-05-18 9:49 ` Peter Zijlstra [this message]
2016-05-18 11:31 ` Michal Hocko
2016-05-19 8:11 ` Peter Zijlstra
2016-05-20 0:17 ` Dave Chinner
2016-06-01 13:17 ` Michal Hocko
2016-06-01 18:16 ` Peter Zijlstra
2016-06-02 14:50 ` Michal Hocko
2016-06-02 15:11 ` Peter Zijlstra
2016-06-02 15:46 ` Michal Hocko
2016-06-02 23:22 ` Dave Chinner
2016-06-06 12:20 ` Michal Hocko
2016-06-15 7:21 ` Dave Chinner
2016-06-21 14:26 ` Michal Hocko
2016-06-22 1:03 ` Dave Chinner
2016-06-22 12:38 ` Michal Hocko
2016-06-22 22:58 ` Dave Chinner
2016-06-23 11:35 ` Michal Hocko
2016-10-06 13:04 ` Michal Hocko
2016-10-17 13:49 ` Michal Hocko
2016-10-19 0:33 ` Dave Chinner
2016-10-19 5:30 ` Dave Chinner
2016-10-19 8:33 ` Peter Zijlstra
2016-10-19 12:06 ` Michal Hocko
2016-10-19 21:49 ` Dave Chinner
2016-10-20 7:15 ` Michal Hocko
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