linux-kernel - Re: kernel BUGs when removing largish files with the SLOB allocator

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Message-ID: <20060912210425.GG19707@waste.org>
Date:	Tue, 12 Sep 2006 16:04:25 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	David Howells <dhowells@...hat.com>
Cc:	Aubrey <aubreylee@...il.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	linux-kernel@...r.kernel.org, davidm@...pgear.com,
	gerg@...pgear.com
Subject: Re: kernel BUGs when removing largish files with the SLOB allocator

On Tue, Sep 12, 2006 at 09:56:46PM +0100, David Howells wrote:
> Matt Mackall <mpm@...enic.com> wrote:
> 
> > > > You just broke the bit that shrinks the arena.
> > > 
> > > How?  This is only called once when things are being initialised.  There can
> > > be no SLOB objects allocated prior to that point.
> > 
> > It's on a timer.
> 
> So what then?  The timer is still initialised:
> 
> 	void kmem_cache_init(void)
> 	{
> 	+#if 0
> 		void *p = slob_alloc(PAGE_SIZE, 0, PAGE_SIZE-1);
> 
> 		if (p)
> 			free_page((unsigned long)p);
> 	+#endif
> 
> 		mod_timer(&slob_timer, jiffies + HZ);
> 	}

"allocate a page from the slob arena"
"if successful, release it to the page allocator"
"re-arm timer"

The only tricky part is the timer points back to _this very function_.

-- 
Mathematics is the supreme nostalgia of our time.
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