Subject: Re: [RFC v11][PATCH 05/13] Dump memory address space
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Mike Waychison <mikew@google.com>
Cc: Oren Laadan <orenl@cs.columbia.edu>, jeremy@goop.org, arnd@arndb.de,
        linux-api@vger.kernel.org, containers@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Linux Torvalds <torvalds@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@elte.hu>
In-Reply-To: <494A9350.1060309@google.com>
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	 <4949B4ED.9060805@google.com> <494A2F94.2090800@cs.columbia.edu>
	 <494A9350.1060309@google.com>
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Date: Thu, 18 Dec 2008 10:21:39 -0800
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On Thu, 2008-12-18 at 10:15 -0800, Mike Waychison wrote:
> 
> >>> +    pgarr = kzalloc(sizeof(*pgarr), GFP_KERNEL);
> >>> +    if (!pgarr)
> >>> +        return NULL;
> >>> +
> >>> +    pgarr->vaddrs = kmalloc(CR_PGARR_TOTAL * sizeof(unsigned
> long),
> >> You used PAGE_SIZE / sizeof(void *) above.   Why not
> __get_free_page()?
> > 
> > Hahaha .. well, it's a guaranteed method to keep Dave Hansen from
> > barking about not using kmalloc ...
> > 
> > Personally I prefer __get_free_page() here, but not enough to keep
> > arguing with him. Let me know when the two of you settle it :)
> 
> Alright, I just wasn't sure if it had been considered.

__get_free_page() sucks.  It doesn't do cool stuff like redzoning when
you have slab debugging turned on.  :)

I would personally suggest never using __get_free_page() unless you
truly need a *PAGE*.  That's an aligned, and PAGE_SIZE chunk.  If you
don't need alignment, or don't literally need a 'struct page', don't use
it.

-- Dave

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