Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From:   Qian Cai <cai@lca.pw>
Mime-Version: 1.0 (1.0)
Subject: Re: [mm/debug] fa6726c1e7: kernel_BUG_at_include/linux/mm.h
Date:   Tue, 28 Apr 2020 04:41:11 -0400
Message-Id: <813D7CD3-F31C-4056-92DF-D462633E9D69@lca.pw>
References: <9e9091b9-6918-d0af-dd92-3bdc0e29a4d5@arm.com>
Cc:     Christophe Leroy <christophe.leroy@c-s.fr>,
        kernel test robot <lkp@intel.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Ingo Molnar <mingo@kernel.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Vineet Gupta <vgupta@synopsys.com>,
        Will Deacon <will@kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, lkp@lists.01.org
In-Reply-To: <9e9091b9-6918-d0af-dd92-3bdc0e29a4d5@arm.com>
To:     Anshuman Khandual <Anshuman.Khandual@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Apr 28, 2020, at 1:54 AM, Anshuman Khandual <Anshuman.Khandual@arm.com>=
 wrote:
>=20
> That is true. There is a slight change in the rules, making it explicit ye=
s
> only when both ARCH_HAS_DEBUG_VM_PGTABLE and DEBUG_VM are enabled.
>=20
> +config DEBUG_VM_PGTABLE
> +    bool "Debug arch page table for semantics compliance"
> +    depends on MMU
> +    depends on !IA64 && !ARM
> +    depends on ARCH_HAS_DEBUG_VM_PGTABLE || EXPERT
> +    default y if ARCH_HAS_DEBUG_VM_PGTABLE && DEBUG_VM
> +    help
>=20
> The default is really irrelevant as the config option can be set explicitl=
y.

That could also explain. Since not long time ago, it was only =E2=80=9Cdefau=
lt y if DEBUG_VM=E2=80=9D, that caused the robot saved a .config with DEBUG_=
VM_PGTABLE=3Dy by default.

Even though you changed the rule recently, it has no effect as the robot cou=
ld =E2=80=9Cmake oldconfig=E2=80=9D from the saved config for each linux-nex=
t tree execution and the breakage will go on.=