rss MM_FILEPAGES statistics value issue in kernel memory remap_pfn_range function.

["xiaowen.liu@xxxxxxxxxxxxx" <xiaowen.liu@xxxxxxxxxxxxx>]

Hi majordomo,

 

Sorry to bother you.

 

I noticed that there are two functions provided to map memory to user space from kernel: remap_pfn_range and vm_insert_page.

There is one difference that vm_insert_page increase task rss MM_FILEPAGES value. But remap_pfn_range doesn’t.

The issue is the munmap function will call zap_pte_range to decrease task rss MM_FILEPAGES value.

So, the task rss MM_FILEPAGES value increase and decrease doesn’t match.

 

And there are many places in kernel driver call remap_pfn_range to map memory to user space.

 

I think remap_pfn_range should also increase task rss MM_FILEPAGES value.

 

If there is any misunderstanding, please correct me.

Thanks.

 

 

BestRegards,

Ivan.liu