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Date: Tue, 17 Aug 2010 14:53:31 +1000 From: Paul Mackerras <paulus@...ba.org> To: Frederic Weisbecker <fweisbec@...il.com> Cc: LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Arnaldo Carvalho de Melo <acme@...hat.com>, Stephane Eranian <eranian@...gle.com>, Will Deacon <will.deacon@....com>, Paul Mundt <lethal@...ux-sh.org>, David Miller <davem@...emloft.net>, Borislav Petkov <bp@...64.org> Subject: Re: [RFC PATCH 5/6 v4] perf: Fix race in callchains On Tue, Aug 17, 2010 at 03:34:06AM +0200, Frederic Weisbecker wrote: > Now that software events don't have interrupt disabled anymore in > the event path, callchains can nest on any context. So seperating > nmi and others contexts in two buffers has become racy. > > Fix this by providing one buffer per nesting level. Given the size > of the callchain entries (2040 bytes * 4), we now need to allocate > them dynamically. > > v2: Fixed put_callchain_entry call after recursion. > Fix the type of the recursion, it must be an array. > > v3: Use a manual pr cpu allocation (temporary solution until NMIs > can safely access vmalloc'ed memory). It would be nice to make these allocations node-local. Also, I see that we're allocating 4 buffers per cpu on powerpc when we strictly only need 3, but I don't suppose that really matters. Paul. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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