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Date:   Mon, 26 Feb 2018 13:05:36 +0000
From:   Mark Rutland <mark.rutland@arm.com>
To:     Mark Salter <msalter@redhat.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf: arm_pmu_acpi: Fix armpmu_alloc call from invalid
 context
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On Thu, Feb 08, 2018 at 12:58:20PM -0500, Mark Salter wrote:
> On Thu, 2018-02-08 at 17:54 +0000, Mark Rutland wrote:
> > Hi Mark,
> > 
> > On Thu, Feb 08, 2018 at 12:45:04PM -0500, Mark Salter wrote:
> > > When booting an arm64 debug kernel with ACPI, I see:
> > > 
> > >    BUG: sleeping function called from invalid context at mm/slab.h:420
> > >    in_atomic(): 0, irqs_disabled(): 128, pid: 12, name: cpuhp/0
> > >    1 lock held by cpuhp/0/12:
> > >     #0:  (cpuhp_state-up){+.+.}, at: [<0000000057aa0dae>] cpuhp_thread_fun+0x13c/0x258
> > >    irq event stamp: 28
> > >    hardirqs last  enabled at (27): [<000000000b861658>] _raw_spin_unlock_irq+0x38/0x58
> > >    hardirqs last disabled at (28): [<000000006231cfb1>] cpuhp_thread_fun+0xd0/0x258
> > >    softirqs last  enabled at (0): [<0000000054d9737a>] copy_process.isra.32.part.33+0x450/0x1480
> > >    softirqs last disabled at (0): [<          (null)>]           (null)
> > >    CPU: 0 PID: 12 Comm: cpuhp/0 Not tainted 4.15.0+ #18
> > >    Hardware name: AppliedMicro X-Gene Mustang Board/X-Gene Mustang Board, BIOS 3.06.25 Oct 17 2016
> > >    Call trace:
> > >     dump_backtrace+0x0/0x188
> > >     show_stack+0x24/0x2c
> > >     dump_stack+0xa4/0xe0
> > >     ___might_sleep+0x208/0x234
> > >     __might_sleep+0x58/0x8c
> > >     kmem_cache_alloc_trace+0x248/0x3e0
> > >     armpmu_alloc+0x38/0x1a8
> > >     arm_pmu_acpi_cpu_starting+0x11c/0x15c
> > >     cpuhp_invoke_callback+0x120/0x100c
> > >     cpuhp_thread_fun+0xe8/0x258
> > >     smpboot_thread_fn+0x170/0x268
> > >     kthread+0x110/0x13c
> > >     ret_from_fork+0x10/0x18
> > 
> > I have patches to address this:
> > 
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2018-February/557838.html
> > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/acpi-pmu-lockdep
> 
> Awesome, I completely missed that. Thanks.

As a heads-up, these were merged in v4.16-rc3.

Mark.