From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Subject: Re: [PATCH] Revert "x86: optimize page faults like all other achitectures and kill notifier cruft"
Date: Wed, 9 Jan 2008 20:07:13 +0100
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Cc: Ingo Molnar <mingo@elte.hu>, David Miller <davem@davemloft.net>,
       hch@lst.de, airlied@linux.ie, akpm@linux-foundation.org,
       torvalds@linux-foundation.org, pq@iki.fi, jbeulich@novell.com,
       linux-kernel@vger.kernel.org,
       Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
       Masami Hiramatsu <mhiramat@redhat.com>
References: <20080108192951.a4dc394f.akpm@linux-foundation.org> <20080109104149.GB8041@elte.hu> <20080109165254.GA4912@Krystal>
In-Reply-To: <20080109165254.GA4912@Krystal>
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> Probing vmalloc faults is _really_ tricky : it also implies that the
> handler (let's call it probe) connected to the probe point (marker or
> kprobe) should _never_ cause a vmalloc page fault, 

That is why vmalloc_sync_all() was invented. It might make sense
to just call that on kprobe registration.

But I agree the other problems makes it a bad idea.

I think the better solution is to keep the notifier, but make 
it cheaper (e.g. by using constant patching ...)

-Andi
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