Message-ID: <1368435991.19924.35.camel@pasglop>
Subject: Re: [RFC PATCH v3 2/5] powerpc: Exception hooks for context
 tracking subsystem
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, paulus@samba.org,
        michael@ellerman.id.au
Date: Mon, 13 May 2013 19:06:31 +1000
In-Reply-To: <1368434680.2618.33.camel@ThinkPad-T5421>
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On Mon, 2013-05-13 at 16:44 +0800, Li Zhong wrote:
> Yes, the above and hash_page() are two C functions for a same exception.
> And the exception hooks enable RCU usage in those C codes. But for asm
> codes, I think we could assume that there would be no RCU usage there,
> so we don't need wrap them in the hooks.

hash_page() won't start a new RCU, at least not in its current incarnation,
the only thing I can see it ever doing would be to take some RCU read locks one
day (it doesn't today).

low_hash_fault() is a different beast. It will typically kill things, thus
involving sending signals etc... RCU might well be involved.

Cheers,
Ben.


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