On Thu, Apr 08, 2021 at 04:43:21PM -0700, Axel Rasmussen wrote:
[...]
> @@ -1820,16 +1821,27 @@ static int shmem_getpage_gfp(struct inode *inode,
> pgoff_t index,
>
> page = pagecache_get_page(mapping, index,
> FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0);
> - if (xa_is_value(page)) {
> + swapped = xa_is_value(page);
> + if (swapped) {
> error = shmem_swapin_page(inode, index, &page,
> sgp, gfp, vma, fault_type);
> if (error == -EEXIST)
> goto repeat;
> -
> *pagep = page;
> - return error;
> + if (error)
> + return error;
> }
>
> + if (page && vma && userfaultfd_minor(vma)) {
> + unlock_page(page);
> + put_page(page);
> + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
> + return 0;
> + }
If we need to consider swapping for UFFDIO_CONTINUE later (as Hugh pointed out
previously, which looks the right thing to do), it's indeed a bit awkward to
swapin here. Maybe move this chunk to right after pagecache_get_page()
returns? Then no need to touch the rest.
> +
> + if (swapped)
> + return 0;
> +
> if (page)
> hindex = page->index;
> if (page && sgp == SGP_WRITE)
> --
> 2.31.1.295.g9ea45b61b8-goog
>
--
Peter Xu
