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Date: Tue, 27 Nov 2001 19:38:22 +0100 (CET)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: <mingo@elte.hu>
To: Maneesh Soni <maneesh@in.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Rusty <rusty@rustcorp.com.au>
Subject: Re: smp_call_function & BH handlers
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On Tue, 27 Nov 2001, Maneesh Soni wrote:

> I am working with Dipankar on Read-Copy Update, and experimenting with
> smp_call_function(). We believed the comments for this routine and
> faced this problem. That's why this question came. I have not yet
> searched kernel sources for such places hence not sure whether there
> are really such places or not.

we had similar lockup problems before, eg. TLB flushes initiated from
IRQ/BH contexts - which is illegal now. Generally it's not safe to assume
that every CPU is responsive to synchronous events triggered from IRQ/BH
contexts. Every read_lock user is prone to this problem.

	Ingo

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