From: Marco Elver <elver@google.com>
To: Anders Roxell <anders.roxell@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>, Jann Horn <jannh@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH] kfence: Avoid stalling work queue task without allocations
Date: Wed, 11 Nov 2020 16:22:20 +0100 [thread overview]
Message-ID: <CANpmjNMBUR-gxDbq5ip4J38PwRHbwOk=zoG5ScVuF6aW326mxQ@mail.gmail.com> (raw)
In-Reply-To: <CADYN=9LtdW3Bs29VSq2ygnNcb3ub_UBLj8tZg5ff5Zvojr5FWg@mail.gmail.com>
On Wed, 11 Nov 2020 at 16:01, Anders Roxell <anders.roxell@linaro.org> wrote:
>
> On Wed, 11 Nov 2020 at 09:29, Marco Elver <elver@google.com> wrote:
> >
> > On Wed, 11 Nov 2020 at 00:23, Anders Roxell <anders.roxell@linaro.org> 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
prev parent reply other threads:[~2020-11-11 15:22 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 13:53 [PATCH] kfence: Avoid stalling work queue task without allocations Marco Elver
2020-11-10 14:25 ` Dmitry Vyukov
2020-11-10 14:53 ` Marco Elver
2020-11-10 23:23 ` Anders Roxell
2020-11-11 8:29 ` Marco Elver
2020-11-11 13:38 ` Marco Elver
2020-11-11 18:05 ` Steven Rostedt
2020-11-11 18:23 ` Paul E. McKenney
2020-11-11 18:34 ` Marco Elver
2020-11-11 19:21 ` Paul E. McKenney
2020-11-11 20:21 ` Marco Elver
2020-11-12 0:11 ` Paul E. McKenney
2020-11-12 12:49 ` Marco Elver
2020-11-12 16:14 ` Marco Elver
2020-11-12 17:54 ` Paul E. McKenney
2020-11-12 18:12 ` Marco Elver
2020-11-12 20:00 ` Paul E. McKenney
2020-11-13 11:06 ` Marco Elver
2020-11-13 17:20 ` Paul E. McKenney
2020-11-13 17:57 ` Paul E. McKenney
2020-11-17 10:52 ` Marco Elver
2020-11-17 18:29 ` Paul E. McKenney
2020-11-18 22:56 ` Marco Elver
2020-11-18 23:38 ` Paul E. McKenney
2020-11-19 12:53 ` Marco Elver
2020-11-19 15:14 ` Paul E. McKenney
2020-11-19 17:02 ` Marco Elver
2020-11-19 18:48 ` Paul E. McKenney
2020-11-19 19:38 ` linux-next: stall warnings and deadlock on Arm64 (was: [PATCH] kfence: Avoid stalling...) Marco Elver
2020-11-19 21:35 ` Paul E. McKenney
2020-11-19 22:53 ` Will Deacon
2020-11-20 10:30 ` Mark Rutland
2020-11-20 14:03 ` Marco Elver
2020-11-23 19:32 ` Mark Rutland
2020-11-24 14:03 ` Marco Elver
2020-11-24 15:01 ` Paul E. McKenney
2020-11-24 19:43 ` Mark Rutland
2020-11-24 20:32 ` Steven Rostedt
2020-11-24 19:30 ` Mark Rutland
2020-11-25 9:45 ` Marco Elver
2020-11-25 10:28 ` Mark Rutland
2020-11-20 14:19 ` Marco Elver
2020-11-20 14:39 ` Paul E. McKenney
2020-11-20 15:22 ` Mark Rutland
2020-11-20 17:38 ` Paul E. McKenney
2020-11-20 18:02 ` Mark Rutland
2020-11-20 18:57 ` Paul E. McKenney
2020-11-20 15:26 ` Steven Rostedt
2020-11-20 18:17 ` Marco Elver
2020-11-20 18:57 ` Steven Rostedt
2020-11-20 19:16 ` Steven Rostedt
2020-11-20 19:22 ` Marco Elver
2020-11-20 19:27 ` [PATCH] kfence: Avoid stalling work queue task without allocations Steven Rostedt
2020-11-23 15:27 ` Marco Elver
2020-11-23 16:28 ` Steven Rostedt
2020-11-23 16:36 ` Steven Rostedt
2020-11-23 18:53 ` Marco Elver
2020-11-23 18:42 ` Steven Rostedt
2020-11-24 2:59 ` Boqun Feng
2020-11-24 3:44 ` Paul E. McKenney
2020-11-11 18:21 ` Paul E. McKenney
2020-11-11 15:01 ` Anders Roxell
2020-11-11 15:22 ` Marco Elver [this message]
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