Re: [PATCH] IB/mlx4: Use vmalloc for WR buffers when needed

[Leon Romanovsky <leon-2ukJVAZIZ/Y@public.gmane.org>]

On Fri, Sep 25, 2015 at 08:51:22AM +0800, Wengang Wang wrote:
> Hi Or,
> 
> 在 2015年09月24日 19:57, Or Gerlitz 写道:
> >On Thu, Sep 24, 2015 at 1:49 PM, Wengang Wang <wen.gang.wang@oracle.com> wrote:
> >>@@ -786,8 +787,14 @@ static int create_qp_common(struct mlx4_ib_dev *dev, struct ib_pd *pd,
> >>                 if (err)
> >>                         goto err_mtt;
> >>
> >>-               qp->sq.wrid  = kmalloc(qp->sq.wqe_cnt * sizeof (u64), gfp);
> >>-               qp->rq.wrid  = kmalloc(qp->rq.wqe_cnt * sizeof (u64), gfp);
> >>+               qp->sq.wrid = kmalloc(qp->sq.wqe_cnt * sizeof(u64), gfp);
> >>+               if (!qp->sq.wrid)
> >>+                       qp->sq.wrid = __vmalloc(qp->sq.wqe_cnt * sizeof(u64),
> >>+                                               gfp, PAGE_KERNEL);
> >On other spots of mlx4, we're using vmalloc and not __vmalloc, any
> >pros/cons for going that way too here?
> 
> vmalloc is just using GFP_KERNEL | __GFP_HIGHMEM, we can't pass in the flag
> gfp with it.  We should respect orginal code which needs to pass the flag.
Additionally, I want to spot Or's attention on the following discussion
in MM-subsystem about kmalloc/vmalloc and general function to fallback
from one to another.

[1] [PATCH 2/7] mm: introduce kvmalloc and kvmalloc_node
https://lkml.org/lkml/2015/7/7/548
[2] [PATCH 0/7] mm: reliable memory allocation with kvmalloc
https://lkml.org/lkml/2015/7/7/545

> 
> thanks,
> wengang
> 
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