linux-kernel - Re: Make sure we populate the initroot filesystem late enough

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Message-ID: <20070226065943.GA3037@holomorphy.com>
Date:	Sun, 25 Feb 2007 22:59:43 -0800
From:	William Lee Irwin III <wli@...omorphy.com>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linuxppc-dev@...abs.org, john stultz <johnstul@...ibm.com>
Subject: Re: Make sure we populate the initroot filesystem late enough

On Sun, Feb 25, 2007 at 11:01:06PM -0500, David Woodhouse wrote:
> Yeah, I did that before giving up on it for the day and going in search
> of dinner. It changes the failure mode to a BUG() in
> cache_free_debugcheck(), at line 2876 of mm/slab.c
> It smells like the pages weren't actually reserved in the first place
> and we were blithely allocating them. The only problem with that theory
> is that the initrd doesn't seem to be getting corrupted -- and if we
> were handing out its pages like that then surely _something_ would have
> scribbled on it before we tried to read it.
> When I head back in tomorrow morning I'll instrument free_initrd_mem()
> to check that the PageReserved bit was actually set on each page, before
> clearing it. And I'll make the page allocation routines check whether
> they're giving out pages between initrd_start and initrd_end, etc.

Another few things to try would be inserting checks in page_alloc.c for
pages in that specific range before some flag set in free_initrd_mem()
is set, and (conflicting with that, though easily reconciled) unmapping
initrd memory in free_initrd_mem() instead of freeing it.


-- wli
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