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Date: Mon, 19 Feb 2007 10:58:08 +0200 (EET) From: Pekka J Enberg <penberg@...helsinki.fi> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, mcr@...delman.ca, clameter@....com Subject: Re: [PATCH] slab: ensure cache_alloc_refill terminates On Mon, 19 Feb 2007, KAMEZAWA Hiroyuki wrote: > From my experience, this infinite loop in cache_alloc_refill() is caused by > double-free, always...(I'm sorry if my knowledge around the slab is too old.) Well, I don't know what exactly caused slabp->inuse (could be cachep->num too, although sounds unlikely) to corrupt for Michael. But yeah, freeing an object twice obviously corrupts slabp->inuse too. On Mon, 19 Feb 2007, KAMEZAWA Hiroyuki wrote: > And it looks this additional check can caught the problem but maybe no help for > fixing problem...How about adding printk like this ? > == > if (unlikely(slabp->inuse >= cachep->num)) { > printk("A problem is detected on slab %s\n", cachep->name);//this information is useful. > printk("please use DEBUG_SLAB kernel for detecting what happens."); > BUG(); > } I don't think cachep->name is enough to debug the problem and as soon as you turn on CONFIG_SLAB_DEBUG double-frees should show up in verify_redzone_free with nice debugging info. So, I'd prefer we keep the simple BUG_ON and simply ask people to turn on debugging if they hit it. Pekka - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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