linux-kernel - Re: [PATCH] x86, percpu: revert commit fe8e0c25

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Message-ID: <20101026132548.GA14666@elte.hu>
Date:	Tue, 26 Oct 2010 15:25:48 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Tejun Heo <tj@...nel.org>
Cc:	torvalds@...l.org, Alexander van Heukelum <heukelum@...tmail.fm>,
	David Howells <dhowells@...hat.com>, akpm@...ux-foundation.org,
	linux-am33-list@...hat.com, linux-kernel@...r.kernel.org,
	Akira Takeuchi <takeuchi.akr@...panasonic.com>,
	Mark Salter <msalter@...hat.com>
Subject: Re: [PATCH] x86, percpu: revert commit fe8e0c25


* Tejun Heo <tj@...nel.org> wrote:

> Commit fe8e0c25 (x86, 32-bit: Align percpu area and irq stacks to THREAD_SIZE) 
> aligned PERCPU section to THREAD_SIZE which can be larger than PAGE_SIZE, 
> introduced DEFINE_PER_CPU_MULTIPAGE_ALIGNED() and used it to make irq stacks 
> aligned to THREAD_SIZE on x86_32.
> 
> This won't work.  The PERCPU output section is used as the template to prepare the 
> percpu area and the actual percpu area is _alwasy_ aligned to PAGE_SIZE whether 
> the source area is aligned to larger size or not.

The problem is, this will reintroduce a nasty boot crash which commit fe8e0c25 
fixed. Do you say that fe8e0c25 didnt have the alignment effect?

	Ingo
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