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From: Steve Capper <Steve.Capper@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Qian Cai <cai@lca.pw>, Andrey Konovalov <andreyknvl@google.com>,
	nd <nd@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: "arm64/for-next/core" causes boot panic
Date: Tue, 13 Aug 2019 14:04:54 +0000	[thread overview]
Message-ID: <20190813140451.GA24579@capper-ampere.manchester.arm.com> (raw)
In-Reply-To: <20190813120643.25y5px4andu6cfwp@willie-the-truck>

Hi Will,

On Tue, Aug 13, 2019 at 01:06:44PM +0100, Will Deacon wrote:
> [+Steve]
> 
> On Tue, Aug 13, 2019 at 11:58:52AM +0100, Will Deacon wrote:
> > On Tue, Aug 13, 2019 at 10:02:01AM +0100, Will Deacon wrote:
> > > On Mon, Aug 12, 2019 at 05:51:35PM -0400, Qian Cai wrote:
> > > > Booting today's linux-next on an arm64 server triggers a panic with
> > > > CONFIG_KASAN_SW_TAGS=y pointing to this line,
> > > 
> > > Is this the only change on top of defconfig? If not, please can you share
> > > your full .config?
> > > 
> > > > kfree()->virt_to_head_page()->compound_head()
> > > > 
> > > > unsigned long head = READ_ONCE(page->compound_head);
> > > > 
> > > > The bisect so far indicates one of those could be bad,
> > > 
> > > I guess that means the issue is reproducible on the arm64 for-next/core
> > > branch. Once I have your .config, I'll give it a go.
> > 
> > FWIW, I've managed to reproduce this using defconfig + SW_TAGS on
> > for-next/core, so I'll keep investigating.

I've installed clang-8 and enabled CONFIG_KASAN_SW_TAGS and was able to
reproduce the problem quite rapidly. Many apologies for missing this
before in my testing.

> 
> Right, hacky diff below seems to resolve this, so I'll split this up into
> some proper patches as there is more than one bug here.
> 
> Thanks,
> 
> Will
> 
> --->8
> 
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
FWIW, this fixed the crashes I experienced, I'll run some additional
tests.

Cheers,
-- 
Steve

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  reply	other threads:[~2019-08-13 14:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-12 21:51 "arm64/for-next/core" causes boot panic Qian Cai
2019-08-13  9:02 ` Will Deacon
2019-08-13 10:58   ` Will Deacon
2019-08-13 12:06     ` Will Deacon
2019-08-13 14:04       ` Steve Capper [this message]
2019-08-13 14:41         ` Steve Capper

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