Re: [PATCH v2 09/20] mm, hugetlb: protect region tracking via newlyintroduced resv_map lock

[Joonsoo Kim]

On Wed, Aug 21, 2013 at 03:43:27PM +0530, Aneesh Kumar K.V wrote:

> >  static long region_chg(struct resv_map *resv, long f, long t)
> >  {
> >  	struct list_head *head = &resv->regions;
> > -	struct file_region *rg, *nrg;
> > +	struct file_region *rg, *nrg = NULL;
> >  	long chg = 0;
> >
> > +retry:
> > +	spin_lock(&resv->lock);
> >  	/* Locate the region we are before or in. */
> >  	list_for_each_entry(rg, head, link)
> >  		if (f <= rg->to)
> > @@ -202,15 +199,27 @@ static long region_chg(struct resv_map *resv, long f, long t)
> >  	 * Subtle, allocate a new region at the position but make it zero
> >  	 * size such that we can guarantee to record the reservation. */
> >  	if (&rg->link == head || t < rg->from) {
> > -		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
> > -		if (!nrg)
> > -			return -ENOMEM;
> > +		if (!nrg) {
> > +			nrg = kmalloc(sizeof(*nrg), GFP_NOWAIT);
> 
> Do we really need to have the GFP_NOWAIT allocation attempt. Why can't we simply say
> allocate and retry ? Or should resv->lock be a mutex ?
> 

Yes, your proposal that simply allocate and retry looks good to me.
I will change it.

Thanks.
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