linux-kernel - Re: Q, slab, kmemleak

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Message-ID: <7595.1259724090@jrobl>
Date:	Wed, 02 Dec 2009 12:21:30 +0900
From:	hooanon05@...oo.co.jp
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: Q, slab, kmemleak_erase() and redzone? 


Pekka Enberg:
> No. The pointer returned by cpu_cache_get() is not changed by 
> cache_alloc_refill(). The contents of the array might change, yes. That 
> said, we should check if objp is NULL before calling kmemleak_erase(). 

To test whether objp is NULL or not is another issue.
'ac' is changed actually. You can confirm it by inserting 
	WARN_ON_ONCE(ac != cpu_cache_get(cachep));
after cache_alloc_refill() in ____cache_alloc().

And do you think these comments/code in cache_alloc_refill() are wrong?
{
	:::
	x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL);

	/* cache_grow can reenable interrupts, then ac could change. */
	ac = cpu_cache_get(cachep);
	:::
}


J. R. Okajima
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