linux-kernel - Re: [RFC v11][PATCH 05/13] Dump memory address space

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Date:	Thu, 18 Dec 2008 10:21:39 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Mike Waychison <mikew@...gle.com>
Cc:	Oren Laadan <orenl@...columbia.edu>, jeremy@...p.org,
	arnd@...db.de, linux-api@...r.kernel.org,
	containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Linux Torvalds <torvalds@...l.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC v11][PATCH 05/13] Dump memory address space

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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