From: "Paul E. McKenney" <paulmck@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: Marco Elver <elver@google.com>,
Matthew Wilcox <willy@infradead.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -next] lib: disable KCSAN for XArray
Date: Wed, 4 Mar 2020 09:14:41 -0800 [thread overview]
Message-ID: <20200304171441.GA2935@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <1583341858.7365.155.camel@lca.pw>
On Wed, Mar 04, 2020 at 12:10:58PM -0500, Qian Cai wrote:
> On Wed, 2020-03-04 at 17:40 +0100, Marco Elver wrote:
> > On Wed, 4 Mar 2020 at 15:10, Paul E. McKenney <paulmck@kernel.org> wrote:
> > >
> > > On Tue, Mar 03, 2020 at 08:33:56PM -0800, Matthew Wilcox wrote:
> > > > On Tue, Mar 03, 2020 at 08:05:15PM -0800, Paul E. McKenney wrote:
> > > > > On Tue, Mar 03, 2020 at 07:33:29PM -0800, Matthew Wilcox wrote:
> > > > > > On Tue, Mar 03, 2020 at 10:15:51PM -0500, Qian Cai wrote:
> > > > > > > Functions like xas_find_marked(), xas_set_mark(), and xas_clear_mark()
> > > > > > > could happen concurrently result in data races, but those operate only
> > > > > > > on a single bit that are pretty much harmless. For example,
> >
> > I currently do not see those as justification to blacklist the whole
> > file. Wouldn't __no_kcsan be better? That is, in case there is no
> > other solution that emerges from the remainder of the discussion here.
>
> I suppose it is up to Matthew. Currently, I can see there are several functions
> may need __no_kcsan,
>
> xa_get_mark(), xas_find_marked(), xas_find_chunk() etc.
>
> My worry was that there could be many of those functions operating on marks
> (which is a single-bit) in xarray that could end up needing the same treatment.
>
> So far, my testing is thin on filesystem side where xarray is pretty much used
> for page caches, so the reports I got from KCSAN runs does not necessary tell
> the whole story. Once I updated my KCSAN runs to include things like xfstests,
> it could add quite a few churns later if we decided to go with the __no_kcsan
> route.
Agreed, the filesystems developers and maintainers will decide how they
would like to approach this.
Thanx, Paul
next prev parent reply other threads:[~2020-03-04 17:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-04 3:15 [PATCH -next] lib: disable KCSAN for XArray Qian Cai
2020-03-04 3:33 ` Matthew Wilcox
2020-03-04 3:55 ` Qian Cai
2020-03-04 4:00 ` Matthew Wilcox
2020-03-04 4:05 ` Paul E. McKenney
2020-03-04 4:33 ` Matthew Wilcox
2020-03-04 14:10 ` Paul E. McKenney
2020-03-04 16:40 ` Marco Elver
2020-03-04 17:10 ` Qian Cai
2020-03-04 17:14 ` Paul E. McKenney [this message]
2020-03-05 15:18 ` Matthew Wilcox
2020-03-05 21:39 ` Paul E. McKenney
2020-03-06 13:38 ` Marco Elver
2020-03-06 16:53 ` Matthew Wilcox
2020-03-06 17:03 ` Paul E. McKenney
2020-03-06 20:04 ` Marco Elver
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