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[67.187.90.124]) by smtp.gmail.com with ESMTPSA id t26sm6842572qkm.0.2021.08.22.21.01.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 22 Aug 2021 21:01:16 -0700 (PDT) Subject: Re: [PATCH] of: Don't allow __of_attached_node_sysfs() without CONFIG_SYSFS To: Marc Zyngier , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Cc: robh+dt@kernel.org, kernel-team@android.com References: <20210820144722.169226-1-maz@kernel.org> From: Frank Rowand Message-ID: Date: Sun, 22 Aug 2021 23:01:15 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210820144722.169226-1-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 8/20/21 9:47 AM, Marc Zyngier wrote: > Trying to boot without SYSFS, but with OF_DYNAMIC quickly > results in a crash: > > [ 0.088460] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070 > [...] > [ 0.103927] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc3 #4179 > [ 0.105810] Hardware name: linux,dummy-virt (DT) > [ 0.107147] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) > [ 0.108876] pc : kernfs_find_and_get_ns+0x3c/0x7c > [ 0.110244] lr : kernfs_find_and_get_ns+0x3c/0x7c > [...] > [ 0.134087] Call trace: > [ 0.134800] kernfs_find_and_get_ns+0x3c/0x7c > [ 0.136054] safe_name+0x4c/0xd0 > [ 0.136994] __of_attach_node_sysfs+0xf8/0x124 > [ 0.138287] of_core_init+0x90/0xfc > [ 0.139296] driver_init+0x30/0x4c > [ 0.140283] kernel_init_freeable+0x160/0x1b8 > [ 0.141543] kernel_init+0x30/0x140 > [ 0.142561] ret_from_fork+0x10/0x18 > > While not having sysfs isn't a very common option these days, > it is still expected that such configuration would work. > > Paper over it by bailing out from __of_attach_node_sysfs() if > CONFIG_SYSFS isn't enabled. CONFIG_SYSFS should be automatically selected when CONFIG_OF_DYNAMIC is enabled, and it should not be possible to disable CONFIG_SYSFS in this case. Can you send your .config? What ARCH did you build the kernel with? Thanks, Frank > > Signed-off-by: Marc Zyngier > --- > drivers/of/kobj.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c > index a32e60b024b8..6675b5e56960 100644 > --- a/drivers/of/kobj.c > +++ b/drivers/of/kobj.c > @@ -119,7 +119,7 @@ int __of_attach_node_sysfs(struct device_node *np) > struct property *pp; > int rc; > > - if (!of_kset) > + if (!IS_ENABLED(CONFIG_SYSFS) || !of_kset) > return 0; > > np->kobj.kset = of_kset; >