netdev - Re: Question about memory leak detector giving false positive report for net/core/flow.c

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Message-ID: <20110927165807.GM14237@e102109-lin.cambridge.arm.com>
Date:	Tue, 27 Sep 2011 17:58:07 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Huajun Li <huajun.li.lee@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	netdev <netdev@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: Question about memory leak detector giving false positive
 report for net/core/flow.c

On Tue, Sep 27, 2011 at 06:55:18AM +0100, Eric Dumazet wrote:
> Yes, it was not a patch, but the general idea for Catalin ;)
> 
> You hit the fact that same zone (embedded percpu space) is now in a
> mixed state.
> 
> In current kernels, the embedded percpu zone is already known by
> kmemleak, but with a large granularity. kmemleak is not aware of
> individual allocations/freeing in this large zone.
> 
> Once kmemleak and percpu allocator are cooperating, we might find more
> kmemleaks. Right now, kmemleak can find pointers in percpu chunks that
> are not anymore reachable (they were freed), and therefore doesnt warn
> of possible memory leaks.

Thanks for suggestions. I need to understand the percpu code a bit
better as it looks that kmemleak is told about some memory blocks twice.

-- 
Catalin
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