On 05/18/2018 10:45 PM, Matthew Wilcox wrote: > From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > > For diagnosing various performance and memory-leak problems, it is helpful > to be able to distinguish pages which are in use as VMalloc pages. > Unfortunately, we cannot use the page_type field in struct page, as > this is in use for mapcount by some drivers which map vmalloced pages > to userspace. > > Use a special page->mapping value to distinguish VMalloc pages from > other kinds of pages. Also record a pointer to the vm_struct and the > offset within the area in struct page to help reconstruct exactly what > this page is being used for. > This seems useless. page->vm_area and page->vm_offset are never used. There are no follow up patches which use this new information 'For diagnosing various performance and memory-leak problems', and no explanation how is it can be used in current form. Also, this patch breaks code like this: if (mapping = page_mapping(page)) // access mapping
