On Wed, 11 Nov 2020 at 16:01, Anders Roxell <anders.roxell@xxxxxxxxxx> wrote: > > On Wed, 11 Nov 2020 at 09:29, Marco Elver <elver@xxxxxxxxxx> wrote: > > > > On Wed, 11 Nov 2020 at 00:23, Anders Roxell <anders.roxell@xxxxxxxxxx> wrote: > > [...] > > > > > > I gave them a spin on next-20201105 [1] and on next-20201110 [2]. > > > > > > I eventually got to a prompt on next-20201105. > > > However, I got to this kernel panic on the next-20201110: > > > > > > [...] > > > [ 1514.089966][ T1] Testing event system initcall: OK > > > [ 1514.806232][ T1] Running tests on all trace events: > > > [ 1514.857835][ T1] Testing all events: > > > [ 1525.503262][ C0] hrtimer: interrupt took 10902600 ns > > > [ 1623.861452][ C0] BUG: workqueue lockup - pool cpus=0 node=0 > > > flags=0x0 nice=0 stuck for 65s! > > > [...] > > > [ 7823.104349][ T28] Tainted: G W > > > 5.10.0-rc3-next-20201110-00008-g8dc06700529d #3 > > > [ 7833.206491][ T28] "echo 0 > > > > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > [ 7840.750700][ T28] task:kworker/0:1 state:D stack:26640 pid: > > > 1872 ppid: 2 flags:0x00000428 > > > [ 7875.642531][ T28] Workqueue: events toggle_allocation_gate > > > [ 7889.178334][ T28] Call trace: > > > [ 7897.066649][ T28] __switch_to+0x1cc/0x1e0 > > > [ 7905.326856][ T28] 0xffff00000f7077b0 > > > [ 7928.354644][ T28] INFO: lockdep is turned off. > > > [ 7934.022572][ T28] Kernel panic - not syncing: hung_task: blocked tasks > > > [ 7934.032039][ T28] CPU: 0 PID: 28 Comm: khungtaskd Tainted: G > > > W 5.10.0-rc3-next-20201110-00008-g8dc06700529d #3 > > > [ 7934.045586][ T28] Hardware name: linux,dummy-virt (DT) > > > [ 7934.053677][ T28] Call trace: > > > [ 7934.060276][ T28] dump_backtrace+0x0/0x420 > > > [ 7934.067635][ T28] show_stack+0x38/0xa0 > > > [ 7934.091277][ T28] dump_stack+0x1d4/0x278 > > > [ 7934.098878][ T28] panic+0x304/0x5d8 > > > [ 7934.114923][ T28] check_hung_uninterruptible_tasks+0x5e4/0x640 > > > [ 7934.123823][ T28] watchdog+0x138/0x160 > > > [ 7934.131561][ T28] kthread+0x23c/0x260 > > > [ 7934.138590][ T28] ret_from_fork+0x10/0x18 > > > [ 7934.146631][ T28] Kernel Offset: disabled > > > [ 7934.153749][ T28] CPU features: 0x0240002,20002004 > > > [ 7934.161476][ T28] Memory Limit: none > > > [ 7934.171272][ T28] ---[ end Kernel panic - not syncing: hung_task: > > > blocked tasks ]--- > > > > > > Cheers, > > > Anders > > > [1] https://people.linaro.org/~anders.roxell/output-next-20201105-test.log > > > [2] https://people.linaro.org/~anders.roxell/output-next-20201110-test.log > > > > Thanks for testing. The fact that it passes on next-20201105 but not > > on 20201110 is strange. If you boot with KFENCE disabled (boot param > > kfence.sample_interval=0), does it boot? > > This is my qemu cmdline with kfence.sample_interval=0 > $ qemu-system-aarch64 --enable-kvm -cpu cortex-a53 -kernel > Image-20201110-test -serial stdio -monitor none -nographic -m 2G -M > virt -fsdev local,id=root,path=/srv/kvm/tmp/stretch/arm64-test,security_model=none,writeout=immediate > -device virtio-rng-pci -device > virtio-9p-pci,fsdev=root,mount_tag=/dev/root -append "root=/dev/root > rootfstype=9p rootflags=trans=virtio console=ttyAMA0,38400n8 > earlycon=pl011,0x9000000 initcall_debug softlockup_panic=0 > security=none kpti=no kfence.sample_interval=0" > > This is the result, I managed to get to the prompt. see > https://people.linaro.org/~anders.roxell/output-next-20201110-test-2.log Hmm, you still have a ton of BUG: workqueue lockup - pool ... and other warnings in that log though that weren't there in next-20201105, so I do not trust the results until those are fixed. To me it looks like KFENCE's timer helps uncover a new problem, but trying to work around this new problem in KFENCE seems wrong for now. We need to understand why these "BUG: workqueue lockup" warnings are there. I Cc'd a bunch of folks in that other email that might be able to help. Thanks, -- Marco
