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Date:   Fri, 22 May 2020 17:49:44 +1000
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Will Deacon <will@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        elver@google.com, bp@alien8.de,
        "Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: linux-next: build failure after merge of the tip tree
Message-ID: <20200522174944.1a1732fa@canb.auug.org.au>
In-Reply-To: <20200522171708.5f392fde@canb.auug.org.au>
References: <20200522033119.1bbd99c5@canb.auug.org.au>
        <20200521173520.GL6608@willie-the-truck>
        <20200522171708.5f392fde@canb.auug.org.au>
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Hi all,

On Fri, 22 May 2020 17:17:08 +1000 Stephen Rothwell <sfr@canb.auug.org.au> =
wrote:
>
> On Thu, 21 May 2020 18:35:22 +0100 Will Deacon <will@kernel.org> wrote:
> >
> > [+Marco and Boris]
> >=20
> > On Fri, May 22, 2020 at 03:31:19AM +1000, Stephen Rothwell wrote: =20
> > > After merging the tip tree, all my linux-next builds took signficantly
> > > longer and used much more memory.  In some cases, builds would seg fa=
ult
> > > due to running out of memory :-(
> > >=20
> > > I have eventaully bisected it to commit
> > >=20
> > >   cdd28ad2d811 ("READ_ONCE: Use data_race() to avoid KCSAN instrument=
ation")
> > >=20
> > > For my (e.g.) x86_64 allmodconfig builds (cross compiled on PowerPC l=
e,
> > > -j80) the elapsed time went from around 9 minutes to over 17 minutes
> > > and the maximum resident size (as reported by /usr/bin/time) from aro=
und
> > > 500M to around 2G (I saw lots of cc1 processes over 2G in size).
> > >=20
> > > For tomorrow's linux-next (well, later today :-() I will revert that
> > > commit (and its child) when I merge the tip tree.   =20
> >=20
> > Sorry about that, seems we can't avoid running into compiler problems w=
ith
> > this lot. The good news is that there's a series to fix this here:
> >=20
> > https://lore.kernel.org/r/20200521142047.169334-1-elver@google.com
> >=20
> > so hopefully this be fixed in -tip soon (but I agree that reverting the
> > thing in -next in the meantime makes sense). =20
>=20
> Unfortunately, the revert didn't work, so instead I have used the tip
> tree from next-20200518 for today (hopefully this will all be sorted
> out by Monday).

And the rcu tree has merged part of the tip tree that contains the
offending commits, so I have used the version fo the rcu tree from
next-20200519 for today.
--=20
Cheers,
Stephen Rothwell

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