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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 1vDLsg-000000026fn-20JA; Mon, 27 Oct 2025 11:59:22 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id EA89C30049D; Mon, 27 Oct 2025 13:54:53 +0100 (CET) Date: Mon, 27 Oct 2025 13:54:53 +0100 From: Peter Zijlstra To: kernel test robot Cc: Fernand Sieber , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, aubrey.li@linux.intel.com, yu.c.chen@intel.com Subject: Re: [tip:sched/core] [sched/fair] 79104becf4: BUG:kernel_NULL_pointer_dereference,address Message-ID: <20251027125453.GY4067720@noisy.programming.kicks-ass.net> References: <202510211205.1e0f5223-lkp@intel.com> <20251021110449.GO3245006@noisy.programming.kicks-ass.net> 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: <20251021110449.GO3245006@noisy.programming.kicks-ass.net> 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,address"= on: > >=20 > > commit: 79104becf42baeeb4a3f2b106f954b9fc7c10a3c ("sched/fair: Forfeit = vruntime on yield") > > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core > >=20 > > [test failed on linux-next/master 606da5bb165594c052ee11de79bf05bc38bc1= aa6] > >=20 > > in testcase: trinity > > version:=20 > > 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/20251021/202510211205.1e0f5223-= lkp@intel.com >=20 >=20 > I'm failing at running the kernel as described in: >=20 > https://download.01.org/0day-ci/archive/20251021/202510211205.1e0f5223-= 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.cgz /u= sr/src/linux-2.6/tmp-build/job-script > result_root: /root/.lkp//result/trinity/group-04-5-300s/vm-snb/quantal-i3= 86-core-20190426.cgz/x86_64-randconfig-121-20251020/gcc-13/79104becf42baeeb= 4a3f2b106f954b9fc7c10a3c/4 > downloading initrds ... > use local modules: /root/.lkp/cache/modules.cgz > skip downloading /root/.lkp/cache/osimage/quantal/quantal-i386-core-20190= 426.cgz > 153636 blocks > skip downloading /root/.lkp/cache/osimage/pkg/quantal-i386-core.cgz/trini= ty-static-i386-x86_64-f93256fb_2019-08-28.cgz > 48101 blocks > exec command: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -fsdev loca= l,id=3Dtest_dev,path=3D/root/.lkp//result/trinity/group-04-5-300s/vm-snb/qu= antal-i386-core-20190426.cgz/x86_64-randconfig-121-20251020/gcc-13/79104bec= f42baeeb4a3f2b106f954b9fc7c10a3c/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/re= sult/trinity/group-04-5-300s/vm-snb/quantal-i386-core-20190426.cgz/x86_64-r= andconfig-121-20251020/gcc-13/79104becf42baeeb4a3f2b106f954b9fc7c10a3c/1 BO= OT_IMAGE=3D/pkg/linux/x86_64-randconfig-121-20251020/gcc-13/79104becf42baee= b4a3f2b106f954b9fc7c10a3c/vmlinuz-6.18.0-rc1-00001-g79104becf42b branch=3Dl= inux-devel/devel-hourly-20251019-154855 job=3D/lkp/jobs/scheduled/vm-meta-2= 91/trinity-group-04-5-300s-quantal-i386-core-20190426.cgz-x86_64-randconfig= -121-20251020-79104becf42b-20251020-124904-8548hu-1.yaml user=3Dlkp ARCH=3D= x86_64 kconfig=3Dx86_64-randconfig-121-20251020 commit=3D79104becf42baeeb4a= 3f2b106f954b9fc7c10a3c intremap=3Dposted_msi vmalloc=3D256M initramfs_async= =3D0 page_owner=3Don carrier_timeout=3D60 rcupdate.rcu_self_test=3D0 max_up= time=3D7200 LKP_LOCAL_RUN=3D1 selinux=3D0 debug apic=3Ddebug sysrq_always_e= nabled rcupdate.rcu_cpu_stall_timeout=3D100 net.ifnames=3D0 printk.devkmsg= =3Don panic=3D-1 softlockup_panic=3D1 nmi_watchdog=3Dpanic oops=3Dpanic loa= d_ramdisk=3D2 prompt_ramdisk=3D0 drbd.minor_count=3D8 systemd.log_level=3De= rr ignore_loglevel console=3Dtty0 earlyprintk=3DttyS0,115200 console=3DttyS= 0,115200 vga=3Dnormal rw ip=3Ddhcp result_service=3D9p/virtfs_mount -initr= d /root/.lkp/cache/final_initrd -smp 2 -m 16384M -no-reboot -device i6300es= b -rtc base=3Dlocaltime -device e1000,netdev=3Dnet0 -netdev user,id=3Dnet0 = -display none -monitor null -serial stdio > [ 5.650807][ T1] Starting init: /bin/sh exists but couldn't execute= it (error -8) > [ 5.651481][ T1] Kernel panic - not syncing: No working init found.= Try passing init=3D option to kernel. See Linux Documentation/admin-guide= /init.rst for guidance. > [ 5.652784][ T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6= =2E18.0-rc2-00182-gbab99e58f91f #35 PREEMPT=20 > [ 5.653668][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 19= 96), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > [ 5.654582][ T1] Call Trace: > [ 5.654873][ T1] > [ 5.655137][ T1] dump_stack_lvl+0x3a/0x70 > [ 5.655536][ T1] dump_stack+0x10/0x20 > [ 5.655911][ T1] vpanic+0x104/0x2c0 > [ 5.656256][ T1] ? rest_init+0x140/0x140 > [ 5.656652][ T1] panic+0x51/0x60 > [ 5.656989][ T1] kernel_init+0x111/0x120 > [ 5.657360][ T1] ret_from_fork+0x25/0x140 > [ 5.657741][ T1] ? rest_init+0x140/0x140 > [ 5.658130][ T1] ret_from_fork_asm+0x11/0x20 > [ 5.658563][ T1] > [ 5.658841][ T1] Kernel Offset: disabled >=20 Any clues how I can get this thing to actually run the trinity required to reproduce instead of panic?