linux-kernel - Re: [PATCH] mm: Fix boot crash in mm

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Date:	Sun, 29 May 2011 10:19:44 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>, linux-mm@...ck.org
Subject: Re: [PATCH] mm: Fix boot crash in mm_alloc()

On Sun, May 29, 2011 at 9:22 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Or, in fact, we could just do something like the attached (UNTESTED!)

So I did warn you that it was untested.

It still is, but I walked through it a bit more, and I realized that
while I had gotten rid of the extra allocations of the
cpu_vm_mask_var, I hadn't gotten rid of the freeing.

So that patch would definitely not have worked very well with
CONFIG_CPUMASK_OFFSTACK.

And I noticed that I moved the cpu_vm_mask back in the wrong space, it
should likely be as close as possible to the mm_context_t, since the
main user is likely the task switching code that touches that anyway.

So here's a slightly updated patch.

STILL TOTALLY UNTESTED! The fixes were just from eyeballing it a bit
more, not from any actual testing.

                      Linus

View attachment "patch.diff" of type "text/x-patch" (4827 bytes)