On Tue, 10 Nov 2020 at 14:54, Marco Elver <elver@xxxxxxxxxx> wrote: > > On Tue, 10 Nov 2020 at 10:36, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > [...] > > > > On Tue, Nov 10, 2020 at 8:50 AM Anders Roxell <anders.roxell@xxxxxxxxxx> wrote: > [...] > > > > > When building an arm64 allmodconfig and booting up that in qemu I see > > > > > > > > > > [10011.092394][ T28] task:kworker/0:2 state:D stack:26896 pid: > > > > > 1840 ppid: 2 flags:0x00000428 > > > > > [10022.368093][ T28] Workqueue: events toggle_allocation_gate > > > > > [10024.827549][ T28] Call trace: > > > > > [10027.152494][ T28] __switch_to+0x1cc/0x1e0 > > > > > [10031.378073][ T28] __schedule+0x730/0x800 > > > > > [10032.164468][ T28] schedule+0xd8/0x160 > > > > > [10033.886807][ T28] toggle_allocation_gate+0x16c/0x220 > > > > > [10038.477987][ T28] process_one_work+0x5c0/0x980 > > > > > [10039.900075][ T28] worker_thread+0x428/0x720 > > > > > [10042.782911][ T28] kthread+0x23c/0x260 > > > > > [10043.171725][ T28] ret_from_fork+0x10/0x18 > > > > > [10046.227741][ T28] INFO: lockdep is turned off. > > > > > [10047.732220][ T28] Kernel panic - not syncing: hung_task: blocked tasks > > > > > [10047.741785][ T28] CPU: 0 PID: 28 Comm: khungtaskd Tainted: G > > > > > W 5.10.0-rc2-next-20201105-00006-g7af110e4d8ed #1 > > > > > [10047.755348][ T28] Hardware name: linux,dummy-virt (DT) > > > > > [10047.763476][ T28] Call trace: > > > > > [10047.769802][ T28] dump_backtrace+0x0/0x420 > > > > > [10047.777104][ T28] show_stack+0x38/0xa0 > > > > > [10047.784177][ T28] dump_stack+0x1d4/0x278 > > > > > [10047.791362][ T28] panic+0x304/0x5d8 > > > > > [10047.798202][ T28] check_hung_uninterruptible_tasks+0x5e4/0x640 > > > > > [10047.807056][ T28] watchdog+0x138/0x160 > > > > > [10047.814140][ T28] kthread+0x23c/0x260 > > > > > [10047.821130][ T28] ret_from_fork+0x10/0x18 > > > > > [10047.829181][ T28] Kernel Offset: disabled > > > > > [10047.836274][ T28] CPU features: 0x0240002,20002004 > > > > > [10047.844070][ T28] Memory Limit: none > > > > > [10047.853599][ T28] ---[ end Kernel panic - not syncing: hung_task: > > > > > blocked tasks ]--- > > > > > > > > > > if I build with KFENCE=n it boots up eventually, here's my .config file [2]. > > > > > > > > > > Any idea what may happen? > > > > > > > > > > it happens on next-20201109 also, but it takes longer until we get the > > > > > "Call trace:". > > > > > > > > > > Cheers, > > > > > Anders > > > > > [1] http://ix.io/2Ddv > > > > > [2] https://people.linaro.org/~anders.roxell/allmodconfig-next-20201105.config > [...] > > > oh I missed to say that this is the full boot log with the kernel > > > panic http://ix.io/2Ddv > > > > Thanks! > > The last messages before the hang are: > > > > [ 1367.791522][ T1] Running tests on all trace events: > > [ 1367.815307][ T1] Testing all events: > > > > I can imagine tracing somehow interferes with kfence. > > The reason is simply that that config on qemu is so slow (enabling > lockdep helped), and the test that is running doesn't result in > allocations for an extended time. Because of that our wait_event() > just stalls, as there are no allocations coming in. My guess is that > this scenario is unique to early boot, where we are not yet running > user space, paired with running a selftest that results in no > allocations for some time. > > Try and give that a spin: > https://lkml.kernel.org/r/20201110135320.3309507-1-elver@xxxxxxxxxx Thank you Marco. I'll give it a spin and reply to that thread if it works or not. Cheers, Anders
