On 01/27/2015 03:06 AM, Joonsoo Kim wrote:
> On Mon, Jan 26, 2015 at 09:26:04AM -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 | 60
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 58 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/cma_debug.c b/mm/cma_debug.c
>> index 3a25413..39c7116 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>
>
> dma-contiguous.h doesn't needed now.
Right.
>> +#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;
>
> How about keeping cma_mem_head on each cma area separately?
Good point, we're mixing allocations here.
>> static int cma_debugfs_get(void *data, u64 *val)
>> @@ -23,8 +36,48 @@ static int cma_debugfs_get(void *data, u64 *val)
>>
>> DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
>>
>> -static void cma_debugfs_add_one(struct cma *cma, int idx)
>> +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(struct cma *cma, int count)
>> {
>> + struct cma_mem *mem;
>> + struct page *p;
>> +
>> + mem = kzalloc(sizeof(*mem), GFP_KERNEL);
>> + if (!mem)
>> + return -ENOMEM;
>> +
>> + p = cma_alloc(cma, count, CONFIG_CMA_ALIGNMENT);
>> + if (!p) {
>> + kfree(mem);
>> + return -ENOMEM;
>> + }
>
> CONFIG_CMA_ALIGNMENT looks not good. It means just maximum aligment
> so it is odd to use this value in testing. Is there special meaning
> to use it here?
No good reason, I stole that from a different piece of code.
> Could we also get alignment parameter from user? Something like below.
>
> echo "4 1" > alloc
> 4 for number of pages
> 1 for alignment.
>
> If it is impossible, just 0 looks better than CONFIG_CMA_ALIGNMENT.
I'd rather keep it simple and use a single parameter for now.
Thanks,
Sasha
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