On Mon, 2017-03-20 at 10:47 +0800, Huang, Ying wrote: > Hi, Tim, > > Tim Chen <[email protected]> writes: > > > > > On Tue, Mar 14, 2017 at 05:25:29PM +0800, Huang, Ying wrote: > > > > > > +struct page *do_swap_page_readahead(struct vm_fault *vmf, > > > + struct vma_swap_readahead *swap_ra, > > > + swp_entry_t fentry, > > > + struct page *fpage) > > > +{ > > > + struct blk_plug plug; > > > + struct vm_area_struct *vma = vmf->vma; > > > + struct page *page; > > > + unsigned long addr; > > > + pte_t *pte, pentry; > > > + gfp_t gfp_mask; > > > + swp_entry_t entry; > > > + int i, alloc = 0, count; > > > + bool page_allocated; > > > + > > > + addr = vmf->address & PAGE_MASK; > > > + blk_start_plug(&plug); > > > + if (!fpage) { > > > + fpage = __read_swap_cache_async(fentry, GFP_HIGHUSER_MOVABLE, > > > + vma, addr, &page_allocated); > > > + if (!fpage) { > > > + blk_finish_plug(&plug); > > > + return NULL; > > > + } > > > + if (page_allocated) { > > > + alloc++; > > > + swap_readpage(fpage); > > > + } > > Do you need to add here a put_page as there's a get_page > > in __read-swap_cache_async? > I don't call put_page() here because the page will be mapped to process > page table. > > > > > put_page(fpage); > > > > I think there is no put_page on the returned page when you return from > > do_swap_page_readahead. > In the original swapin_readahead(), the read_swap_cache_async() will be > called for the fault swap entry again in the end of the function, and > pug_page() is not called there. >
I missed the second call to read_swap_cache_async in swapin_readahead. You're right that we should keep the reference on the faulted page and not call put_page on fpage here. Thanks. Tim
