linux-kernel - Re: [REVIEW] NVM Express driver

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Message-ID: <m24o79cmv4.fsf@firstfloor.org>
Date:	Fri, 11 Mar 2011 14:29:19 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	Matthew Wilcox <willy@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [REVIEW] NVM Express driver

Matthew Wilcox <willy@...ux.intel.com> writes:
> +
> +static struct nvme_queue *get_nvmeq(struct nvme_ns *ns)
> +{
> +	int qid, cpu = get_cpu();
> +	if (cpu < ns->dev->queue_count)
> +		qid = cpu + 1;
> +	else
> +		qid = (cpu % rounddown_pow_of_two(ns->dev->queue_count))
> + 1;

This will be likely a full divide, better use a mask.

> +	nprps = DIV_ROUND_UP(length, PAGE_SIZE);
> +	npages = DIV_ROUND_UP(8 * nprps, PAGE_SIZE);
> +	prps = kmalloc(sizeof(*prps) + sizeof(__le64 *) * npages, GFP_ATOMIC);
> +	prp_page = 0;
> +	if (nprps <= (256 / 8)) {
> +		pool = dev->prp_small_pool;
> +		prps->npages = 0;


Unchecked GFP_ATOMIC allocation? That will oops soon.
Besides GFP_ATOMIC a very risky thing to do on a low memory situation,
which can trigger writeouts.


> +	} else {
> +		pool = dev->prp_page_pool;
> +		prps->npages = npages;
> +	}
> +
> +	prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
> +	prps->list[prp_page++] = prp_list;

And another one.


Didn't read all of it.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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