Re: [PATCH 1/3] IB/ehca: Replace vmalloc with kmalloc

From: michael
Date: Wed Apr 22 2009 - 12:32:01 EST


Hi,

Stefan Roscher wrote:
In case of large queue pairs there is the possibillity of allocation failures due to memory fragmentationo with kmalloc().To ensure the memory is allocated even
if kmalloc() can not find chunks which are big enough, we try to allocate the memory
with vmalloc().

Signed-off-by: Stefan Roscher <stefan.roscher@xxxxxxxxxx>
---

On Tuesday 21 April 2009 07:34:30 pm Roland Dreier wrote:
> + queue->queue_pages = kmalloc(nr_of_pages * sizeof(void *), GFP_KERNEL);

How big might this buffer be? Any chance of allocation failure due to
memory fragmentation?

- R.
Hey Roland, yes you are right and here is the patch to circumvent the described problem.
It will apply on top of the patchset.
regards Stefan

I don't take the point, if it is not import use the vmalloc. Why you try with a kmalloc
alloc first? and why do not use kzalloc?
drivers/infiniband/hw/ehca/ipz_pt_fn.c | 17 +++++++++++++----
1 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/ehca/ipz_pt_fn.c b/drivers/infiniband/hw/ehca/ipz_pt_fn.c
index a260559..1227c59 100644
--- a/drivers/infiniband/hw/ehca/ipz_pt_fn.c
+++ b/drivers/infiniband/hw/ehca/ipz_pt_fn.c
@@ -222,8 +222,11 @@ int ipz_queue_ctor(struct ehca_pd *pd, struct ipz_queue *queue,
/* allocate queue page pointers */
queue->queue_pages = kmalloc(nr_of_pages * sizeof(void *), GFP_KERNEL);
if (!queue->queue_pages) {
- ehca_gen_err("Couldn't allocate queue page list");
- return 0;
+ queue->queue_pages = vmalloc(nr_of_pages * sizeof(void *));
+ if (!queue->queue_pages) {
+ ehca_gen_err("Couldn't allocate queue page list");
+ return 0;
+ }
}
memset(queue->queue_pages, 0, nr_of_pages * sizeof(void *));
@@ -240,7 +243,10 @@ int ipz_queue_ctor(struct ehca_pd *pd, struct ipz_queue *queue,
ipz_queue_ctor_exit0:
ehca_gen_err("Couldn't alloc pages queue=%p "
"nr_of_pages=%x", queue, nr_of_pages);
- kfree(queue->queue_pages);
+ if (is_vmalloc_addr(queue->queue_pages))
+ vfree(queue->queue_pages);
+ else
+ kfree(queue->queue_pages);
return 0;
}
@@ -262,7 +268,10 @@ int ipz_queue_dtor(struct ehca_pd *pd, struct ipz_queue *queue)
free_page((unsigned long)queue->queue_pages[i]);
}
- kfree(queue->queue_pages);
+ if (is_vmalloc_addr(queue->queue_pages))
+ vfree(queue->queue_pages);
+ else
+ kfree(queue->queue_pages);
return 1;
}

Regards Michael
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