Messages in this thread | | | Date | Thu, 09 Nov 2023 15:43:10 +0000 | From | jeff.xie@linux ... | Subject | Re: [RFC][PATCH 3/4] filemap: implement filemap allocate post callback for page_owner |
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November 9, 2023 at 10:09 PM, "Matthew Wilcox" <willy@infradead.org> wrote:
> > On Thu, Nov 09, 2023 at 11:25:20AM +0800, Jeff Xie wrote: > > > > > +static int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk, > > + void *data, char *kbuf, size_t count) > > +{ > > + int ret; > > + int mapcount; > > + dev_t s_dev; > > + struct inode *inode; > > + struct vm_area_struct *vma; > > + struct mm_struct *mm; > > + unsigned long virtual_start = 0x0; > > + unsigned long virtual_end = 0x0; > > + struct address_space *mapping = data; > > > > This is just folio->mapping.
Thanks, I need to know more about struct folio ;-)
> > > > > + mapcount = folio_mapcount(folio); > > + if (mapcount && tsk && tsk->mm) { > > + mm = tsk->mm; > > + VMA_ITERATOR(vmi, mm, 0); > > + mmap_read_lock(mm); > > + for_each_vma(vmi, vma) { > > + if (page_mapped_in_vma(&folio->page, vma)) { > > + virtual_start = vma_address(&folio->page, vma); > > + virtual_end = virtual_start + folio_nr_pages(folio) * PAGE_SIZE; > > + break; > > + } > > + } > > + mmap_read_unlock(mm); > > + } > > > > Why not just walk the rmap directly to find out where it's mapped in > any process instead of the one which allocated it?
Since the page_owner's result only shows which PID allocated this page, we only need to obtain the address space of the corresponding process for that PID.
-- Jeff Xie
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