Hi, Tim,
Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> 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.
Best Regards,
Huang, Ying
> Thanks.
>
> Tim
>
>> + }
>> + /* fault page has been checked */
>> + count = 1;
>> + addr += PAGE_SIZE * swap_ra->direction;
>> + pte = swap_ra->ptes;
>> + if (swap_ra->direction < 0)
>> + pte += swap_ra->nr_pte - 1;
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