linux-kernel - Re: [PATCH] perf/x86/intel: Avoid unnecessary reallocations of memory allocated in cpu hotplug prepare state

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Message-ID: <20181218113119.GG15430@hirez.programming.kicks-ass.net>
Date:   Tue, 18 Dec 2018 12:31:19 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     zhe.he@...driver.com, acme@...nel.org, ak@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, bp@...en8.de, hpa@...or.com,
        jolsa@...nel.org, jolsa@...hat.com, kan.liang@...ux.intel.com,
        mingo@...hat.com, namhyung@...nel.org, tglx@...utronix.de,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH] perf/x86/intel: Avoid unnecessary reallocations of
 memory allocated in cpu hotplug prepare state

On Tue, Dec 18, 2018 at 12:16:37PM +0100, Sebastian Andrzej Siewior wrote:
> On 2018-12-18 12:02:09 [+0100], Peter Zijlstra wrote:
> > On Tue, Dec 18, 2018 at 06:30:33PM +0800, zhe.he@...driver.com wrote:
> > > Besides, in preempt-rt full mode, the freeing can happen in atomic context and
> > > thus cause the following BUG.
> > 
> > Hurm, I though we fixed all those long ago..
> > 
> > And no, the patch is horrible; that's what we have things like
> > x86_pmu::cpu_dead() for.
> 
> ehm, you say we keep memory allocation +free on CPU up/down?

Sure, why not?