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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vDMp7-00000002Ejz-2h2b; Mon, 27 Oct 2025 12:59:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 928F2300323; Mon, 27 Oct 2025 14:55:16 +0100 (CET) Date: Mon, 27 Oct 2025 14:55:16 +0100 From: Peter Zijlstra To: "Chen, Yu C" Cc: kernel test robot , Fernand Sieber , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, aubrey.li@linux.intel.com Subject: Re: [tip:sched/core] [sched/fair] 79104becf4: BUG:kernel_NULL_pointer_dereference,address Message-ID: <20251027135516.GA3419281@noisy.programming.kicks-ass.net> References: <202510211205.1e0f5223-lkp@intel.com> <20251021110449.GO3245006@noisy.programming.kicks-ass.net> <20251027125453.GY4067720@noisy.programming.kicks-ass.net> <3b30e40b-f1fb-4145-b4d9-a9279b9602d8@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <3b30e40b-f1fb-4145-b4d9-a9279b9602d8@intel.com> On Mon, Oct 27, 2025 at 09:14:11PM +0800, Chen, Yu C wrote: > On 10/27/2025 8:54 PM, Peter Zijlstra wrote: > > On Tue, Oct 21, 2025 at 01:04:49PM +0200, Peter Zijlstra wrote: > > > On Tue, Oct 21, 2025 at 01:14:36PM +0800, kernel test robot wrote: > > > >=20 > > > >=20 > > > > Hello, > > > >=20 > > > > kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,addr= ess" on: > > > >=20 > > > > commit: 79104becf42baeeb4a3f2b106f954b9fc7c10a3c ("sched/fair: Forf= eit vruntime on yield") > > > > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core > > > >=20 > > > > [test failed on linux-next/master 606da5bb165594c052ee11de79bf05bc3= 8bc1aa6] > > > >=20 > > > > in testcase: trinity > > > > version: > > > > with following parameters: > > > >=20 > > > > runtime: 300s > > > > group: group-04 > > > > nr_groups: 5 > > > >=20 > > > >=20 > > > >=20 > > > > config: x86_64-randconfig-121-20251020 > > > > compiler: gcc-13 > > > > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp = 2 -m 16G > > > >=20 > > >=20 > > > > The kernel config and materials to reproduce are available at: > > > > https://download.01.org/0day-ci/archive/20251021/202510211205.1e0f5= 223-lkp@intel.com > > >=20 > > >=20 > > > I'm failing at running the kernel as described in: > > >=20 > > > https://download.01.org/0day-ci/archive/20251021/202510211205.1e0f= 5223-lkp@intel.com/reproduce > > >=20 > > >=20 > > > I then start the test as: > > >=20 > > > root@spr:/usr/local/src/lkp-tests# bin/lkp qemu -k /usr/src/linux-2.6= /tmp-build/arch/x86/boot/bzImage -m /usr/src/linux-2.6/tmp-build/modules.cg= z /usr/src/linux-2.6/tmp-build/job-script > > > result_root: /root/.lkp//result/trinity/group-04-5-300s/vm-snb/quanta= l-i386-core-20190426.cgz/x86_64-randconfig-121-20251020/gcc-13/79104becf42b= aeeb4a3f2b106f954b9fc7c10a3c/4 > > > downloading initrds ... > > > use local modules: /root/.lkp/cache/modules.cgz > > > skip downloading /root/.lkp/cache/osimage/quantal/quantal-i386-core-2= 0190426.cgz > > > 153636 blocks > > > skip downloading /root/.lkp/cache/osimage/pkg/quantal-i386-core.cgz/t= rinity-static-i386-x86_64-f93256fb_2019-08-28.cgz > > > 48101 blocks > > > exec command: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -fsdev = local,id=3Dtest_dev,path=3D/root/.lkp//result/trinity/group-04-5-300s/vm-sn= b/quantal-i386-core-20190426.cgz/x86_64-randconfig-121-20251020/gcc-13/7910= 4becf42baeeb4a3f2b106f954b9fc7c10a3c/4,security_model=3Dnone -device virtio= -9p-pci,fsdev=3Dtest_dev,mount_tag=3D9p/virtfs_mount -kernel /usr/src/linux= -2.6/tmp-build/arch/x86/boot/bzImage -append root=3D/dev/ram0 RESULT_ROOT= =3D/result/trinity/group-04-5-300s/vm-snb/quantal-i386-core-20190426.cgz/x8= 6_64-randconfig-121-20251020/gcc-13/79104becf42baeeb4a3f2b106f954b9fc7c10a3= c/1 BOOT_IMAGE=3D/pkg/linux/x86_64-randconfig-121-20251020/gcc-13/79104becf= 42baeeb4a3f2b106f954b9fc7c10a3c/vmlinuz-6.18.0-rc1-00001-g79104becf42b bran= ch=3Dlinux-devel/devel-hourly-20251019-154855 job=3D/lkp/jobs/scheduled/vm-= meta-291/trinity-group-04-5-300s-quantal-i386-core-20190426.cgz-x86_64-rand= config-121-20251020-79104becf42b-20251020-124904-8548hu-1.yaml user=3Dlkp A= RCH=3Dx86_64 kconfig=3Dx86_64-randconfig-121-20251020 commit=3D79104becf42b= aeeb4a3f2b106f954b9fc7c10a3c intremap=3Dposted_msi vmalloc=3D256M initramfs= _async=3D0 page_owner=3Don carrier_timeout=3D60 rcupdate.rcu_self_test=3D0 = max_uptime=3D7200 LKP_LOCAL_RUN=3D1 selinux=3D0 debug apic=3Ddebug sysrq_al= ways_enabled rcupdate.rcu_cpu_stall_timeout=3D100 net.ifnames=3D0 printk.de= vkmsg=3Don panic=3D-1 softlockup_panic=3D1 nmi_watchdog=3Dpanic oops=3Dpani= c load_ramdisk=3D2 prompt_ramdisk=3D0 drbd.minor_count=3D8 systemd.log_leve= l=3Derr ignore_loglevel console=3Dtty0 earlyprintk=3DttyS0,115200 console= =3DttyS0,115200 vga=3Dnormal rw ip=3Ddhcp result_service=3D9p/virtfs_mount= -initrd /root/.lkp/cache/final_initrd -smp 2 -m 16384M -no-reboot -device = i6300esb -rtc base=3Dlocaltime -device e1000,netdev=3Dnet0 -netdev user,id= =3Dnet0 -display none -monitor null -serial stdio > >=20 > > > [ 5.650807][ T1] Starting init: /bin/sh exists but couldn't exe= cute it (error -8) >=20 > May I know if you are using the kernel config 0day attached? > I found that the config 0day attached > (https://download.01.org/0day-ci/archive/20251021/202510211205.1e0f5223-l= kp@intel.com/config-6.18.0-rc1-00001-g79104becf42b) > has > CONFIG_IA32_EMULATION=3Dy > CONFIG_IA32_EMULATION_DEFAULT_DISABLED=3Dy > CONFIG_COMPAT_32=3Dy > CONFIG_COMPAT=3Dy >=20 > It is suspected that the filesystem provided by lkp is 32bits, might > need Oliver's confirm. It was certainly meant to be that config -- let be double check that.