On Sun, Nov 19, 2023 at 11:48 AM Kairui Song <ryncsn@xxxxxxxxx> wrote:
>
> From: Kairui Song <kasong@xxxxxxxxxxx>
>
> Move get_swap_device into swapin_readahead, simplify the code
> and prepare for follow up commits.
>
> For the later part in do_swap_page, using swp_swap_info directly is fine
> since in that context, the swap device is pinned by swapcache reference.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> ---
> mm/memory.c | 16 ++++------------
> mm/swap_state.c | 8 ++++++--
> mm/swapfile.c | 4 +++-
> 3 files changed, 13 insertions(+), 15 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 22af9f3e8c75..e399b37ef395 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3789,7 +3789,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> struct folio *swapcache = NULL, *folio = NULL;
> enum swap_cache_result cache_result;
> struct page *page;
> - struct swap_info_struct *si = NULL;
> rmap_t rmap_flags = RMAP_NONE;
> bool exclusive = false;
> swp_entry_t entry;
> @@ -3845,14 +3844,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> goto out;
> }
>
> - /* Prevent swapoff from happening to us. */
> - si = get_swap_device(entry);
> - if (unlikely(!si))
> - goto out;
> -
> page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
> vmf, &cache_result);
> - if (page) {
> + if (PTR_ERR(page) == -EBUSY) {
> + goto out;
> + } else if (page) {
As Matthew suggested, using ERR_PTR(-EBUSY).
you also don't need the else here. The goto already terminates the flow.
if (page == ERR_PTR(-EBUSY))
goto out;
if (page) {
Chris
