On 01/22/2015 03:26 AM, Joonsoo Kim wrote:
> On Tue, Jan 20, 2015 at 12:38:32PM -0500, Sasha Levin wrote:
>> Provides a userspace interface to trigger a CMA allocation.
>>
>> Usage:
>>
>> echo [pages] > alloc
>>
>> This would provide testing/fuzzing access to the CMA allocation paths.
>>
>> Signed-off-by: Sasha Levin <sasha.le...@oracle.com>
>> ---
>> mm/cma_debug.c | 58
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 58 insertions(+)
>>
>> diff --git a/mm/cma_debug.c b/mm/cma_debug.c
>> index 3a25413..eda0a41 100644
>> --- a/mm/cma_debug.c
>> +++ b/mm/cma_debug.c
>> @@ -7,9 +7,22 @@
>>
>> #include <linux/debugfs.h>
>> #include <linux/cma.h>
>> +#include <linux/list.h>
>> +#include <linux/kernel.h>
>> +#include <linux/dma-contiguous.h>
>> +#include <linux/slab.h>
>>
>> #include "cma.h"
>>
>> +struct cma_mem {
>> + struct hlist_node node;
>> + struct page *p;
>> + unsigned long n;
>> +};
>> +
>> +static HLIST_HEAD(cma_mem_head);
>> +static DEFINE_SPINLOCK(cma_mem_head_lock);
>> +
>> static struct dentry *cma_debugfs_root;
>>
>> static int cma_debugfs_get(void *data, u64 *val)
>> @@ -44,6 +57,48 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
>> debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap,
>> u32s);
>> }
>>
>> +static void cma_add_to_cma_mem_list(struct cma_mem *mem)
>> +{
>> + spin_lock(&cma_mem_head_lock);
>> + hlist_add_head(&mem->node, &cma_mem_head);
>> + spin_unlock(&cma_mem_head_lock);
>> +}
>> +
>> +static int cma_alloc_mem(int count)
>> +{
>> + struct cma_mem *mem;
>> + struct page *p;
>> +
>> + mem = kzalloc(sizeof(*mem), GFP_KERNEL);
>> + if (!mem)
>> + return -ENOMEM;
>> +
>> + p = cma_alloc(dma_contiguous_default_area, count, CONFIG_CMA_ALIGNMENT);
>> + if (!p) {
>> + pr_info("CMA: Allocation failed.\n");
>> + kfree(mem);
>> + return -ENOMEM;
>> + }
>
> Hello,
>
> I'm glad to see this patchset. I had similar one privately. :)
> Without this kind of facility, testing CMA is really hard.
>
> Anyway, dma_contiguous_default_area is defined only in CONFIG_DMA_CMA.
> So, it would cause build break.
>
> And, I think that it is better for this tester to have an ability to
> allocate pages on specific CMA reserved region. It could be easily
> achieved by moving 'alloc' registration to cma_debugfs_add_one(). Is
> there any reason not to do that?
Agreed, that would make more sense.
>> +
>> + pr_info("CMA: Allocated %d pages at %p\n", count, p);
>
> I don't think this output is needed. If CONFIG_CMA_DEBUG is enabled,
> cma_alloc() print similar output.
I didn't see any other output (and I have CONFIG_CMA_DEBUG set), which
is why I've added this pr_info().
Thanks,
Sasha
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