linux-kernel - Re: [PATCH v2][RESEND] perf, x86: Fix multi-segment problem of perf_event_intel

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Message-ID: <20150901113939.GS19282@twins.programming.kicks-ass.net>
Date:	Tue, 1 Sep 2015 13:39:39 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Taku Izumi <izumi.taku@...fujitsu.com>,
	linux-kernel@...r.kernel.org, mingo@...hat.com, acme@...nel.org,
	hpa@...or.com, x86@...nel.org, jolsa@...hat.com
Subject: Re: [PATCH v2][RESEND] perf, x86: Fix multi-segment problem of
 perf_event_intel_uncore

On Tue, Sep 01, 2015 at 01:31:47PM +0200, Ingo Molnar wrote:
> 
> * Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > +struct __find_pci2phy(int segment)
> > +{
> > +	struct pci2phy_map *map;
> > +
> > +	lockdep_assert_held(&pci2phy_map_lock);
> > +
> > +	list_for_each_entry(map, &pci2phy_map_head, list) {
> > +		if (map->segment == segment)
> > +			return map;
> > +	}
> > +
> > +	map = kmalloc(sizeof(struct pci2phy_map), GFP_ATOMIC);
> 
> I really don't think we should be adding new GFP_ATOMIC allocations whenever it 
> can be avoided.

I tend to agree, it makes the whole thing rather fragile...
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