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Subject: Re: [PATCH v4] mm: cma: support sysfs
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Minchan Kim <minchan@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, joaodias@google.com,
        willy@infradead.org, david@redhat.com, surenb@google.com,
        John Hubbard <jhubbard@nvidia.com>,
        Nicolas Chauvet <kwizart@gmail.com>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <33ec18ef-8652-643a-1a53-ff7c3caf4399@gmail.com>
Date:   Fri, 19 Mar 2021 16:51:29 +0300
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19.03.2021 16:47, Greg Kroah-Hartman пишет:
> On Fri, Mar 19, 2021 at 04:45:21PM +0300, Dmitry Osipenko wrote:
>> 19.03.2021 16:42, Greg Kroah-Hartman пишет:
>>> On Fri, Mar 19, 2021 at 04:39:41PM +0300, Dmitry Osipenko wrote:
>>>> 19.03.2021 15:44, Dmitry Osipenko пишет:
>>>> ...
>>>>>>  #include <linux/debugfs.h>
>>>>>> +#include <linux/kobject.h>
>>>>>> +
>>>>>> +struct cma_stat {
>>>>>> +	spinlock_t lock;
>>>>>> +	/* the number of CMA page successful allocations */
>>>>>> +	unsigned long nr_pages_succeeded;
>>>>>> +	/* the number of CMA page allocation failures */
>>>>>> +	unsigned long nr_pages_failed;
>>>>>> +	struct kobject kobj;
>>>>>> +};
>>>>>>  
>>>>>>  struct cma {
>>>>>>  	unsigned long   base_pfn;
>>>>>> @@ -16,6 +26,9 @@ struct cma {
>>>>>>  	struct debugfs_u32_array dfs_bitmap;
>>>>>>  #endif
>>>>>>  	char name[CMA_MAX_NAME];
>>>>>> +#ifdef CONFIG_CMA_SYSFS
>>>>>> +	struct cma_stat	*stat;
>>>>>> +#endif
>>>>
>>>> What is the point of allocating stat dynamically?
>>>
>>> Because static kobjects make me cry.
>>>
>>
>> I meant that it's already a part of struct cma, it looks like the stat
>> could be embedded into struct cma and then kobj could be initialized
>> separately.
> 
> But that structure is statically allocated, so it can not be.  This has
> been discussed in the past threads for when this was reviewed if you are
> curious :)

Indeed, I missed that cma_areas[] is static, thank you.