linux-kernel - Re: [SPLAT 1/3] arm_pmu: Sleeping spinlocks down armpmu_alloc

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Message-ID: <20210810135453.roczkohgm2lzhg66@linutronix.de>
Date:   Tue, 10 Aug 2021 15:54:53 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [SPLAT 1/3] arm_pmu: Sleeping spinlocks down
 armpmu_alloc_atomic()

On 2021-08-10 14:41:25 [+0100], Valentin Schneider wrote:
> [    4.172817] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35

Would it work to allocate the memory upfront and invoke the HP callback
via smp_function_call()? That is implemented via the hp-callback. It is
invoked after all CPUs are up. There is one "memory allocation" per
"node". This does not change during runtime, right?

Sebastian