linux-kernel - Re: [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

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Message-ID: <d822adcc-2a3c-1923-0d1d-4ecabd76a0e5@sony.com>
Date:   Sat, 17 Apr 2021 11:20:33 +0000
From:   <Peter.Enderborg@...y.com>
To:     <christian.koenig@....com>, <linux-kernel@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>, <sumit.semwal@...aro.org>,
        <adobriyan@...il.com>, <akpm@...ux-foundation.org>,
        <songmuchun@...edance.com>, <guro@...com>, <shakeelb@...gle.com>,
        <mhocko@...e.com>, <neilb@...e.de>, <samitolvanen@...gle.com>,
        <rppt@...nel.org>, <linux-media@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        <linaro-mm-sig@...ts.linaro.org>, <willy@...radead.org>
Subject: Re: [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

On 4/17/21 12:59 PM, Christian König wrote:
> Am 17.04.21 um 12:40 schrieb Peter Enderborg:
>> This adds a total used dma-buf memory. Details
>> can be found in debugfs, however it is not for everyone
>> and not always available. dma-buf are indirect allocated by
>> userspace. So with this value we can monitor and detect
>> userspace applications that have problems.
>>
>> Signed-off-by: Peter Enderborg <peter.enderborg@...y.com>
>
> Reviewed-by: Christian König <christian.koenig@....com>
>
> How do you want to upstream this?

I don't understand that question. The patch applies on Torvalds 5.12-rc7,
but I guess 5.13 is what we work on right now.

>
>> ---
>>   drivers/dma-buf/dma-buf.c | 13 +++++++++++++
>>   fs/proc/meminfo.c         |  5 ++++-
>>   include/linux/dma-buf.h   |  1 +
>>   3 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index f264b70c383e..197e5c45dd26 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -37,6 +37,7 @@ struct dma_buf_list {
>>   };
>>     static struct dma_buf_list db_list;
>> +static atomic_long_t dma_buf_global_allocated;
>>     static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
>>   {
>> @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry)
>>       if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
>>           dma_resv_fini(dmabuf->resv);
>>   +    atomic_long_sub(dmabuf->size, &dma_buf_global_allocated);
>>       module_put(dmabuf->owner);
>>       kfree(dmabuf->name);
>>       kfree(dmabuf);
>> @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>>       mutex_lock(&db_list.lock);
>>       list_add(&dmabuf->list_node, &db_list.head);
>>       mutex_unlock(&db_list.lock);
>> +    atomic_long_add(dmabuf->size, &dma_buf_global_allocated);
>>         return dmabuf;
>>   @@ -1346,6 +1349,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
>>   }
>>   EXPORT_SYMBOL_GPL(dma_buf_vunmap);
>>   +/**
>> + * dma_buf_allocated_pages - Return the used nr of pages
>> + * allocated for dma-buf
>> + */
>> +long dma_buf_allocated_pages(void)
>> +{
>> +    return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT;
>> +}
>> +EXPORT_SYMBOL_GPL(dma_buf_allocated_pages);
>> +
>>   #ifdef CONFIG_DEBUG_FS
>>   static int dma_buf_debug_show(struct seq_file *s, void *unused)
>>   {
>> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
>> index 6fa761c9cc78..ccc7c40c8db7 100644
>> --- a/fs/proc/meminfo.c
>> +++ b/fs/proc/meminfo.c
>> @@ -16,6 +16,7 @@
>>   #ifdef CONFIG_CMA
>>   #include <linux/cma.h>
>>   #endif
>> +#include <linux/dma-buf.h>
>>   #include <asm/page.h>
>>   #include "internal.h"
>>   @@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>>       show_val_kb(m, "CmaFree:        ",
>>               global_zone_page_state(NR_FREE_CMA_PAGES));
>>   #endif
>> -
>> +#ifdef CONFIG_DMA_SHARED_BUFFER
>> +    show_val_kb(m, "DmaBufTotal:    ", dma_buf_allocated_pages());
>> +#endif
>>       hugetlb_report_meminfo(m);
>>         arch_report_meminfo(m);
>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
>> index efdc56b9d95f..5b05816bd2cd 100644
>> --- a/include/linux/dma-buf.h
>> +++ b/include/linux/dma-buf.h
>> @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
>>            unsigned long);
>>   int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
>>   void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
>> +long dma_buf_allocated_pages(void);
>>   #endif /* __DMA_BUF_H__ */
>