Re: [PATCH] Revert "mm, swap: avoid redundant swap device pinning"

On Mon, Nov 10, 2025 at 7:37 PM Kairui Song ryncsn@gmail.com wrote:

diff --git a/mm/swap_state.c b/mm/swap_state.c index 3f85a1c4cfd9..4cca4865627f 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -747,6 +747,7 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask,

    blk_start_plug(&plug);
    for (addr = start; addr < end; ilx++, addr += PAGE_SIZE) {

•           struct swap_info_struct *si = NULL;
            leaf_entry_t entry;
  
            if (!pte++) {
  

@@ -761,8 +762,12 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask, continue; pte_unmap(pte); pte = NULL;

•           if (swp_type(entry) != swp_type(targ_entry))
  

•                   si = get_swap_device(entry);
  

Oops I missed a NULL check here.

            folio = __read_swap_cache_async(entry, gfp_mask, mpol, ilx,
                                            &page_allocated, false);

•           if (si)
  

•                   put_swap_device(si);
            if (!folio)
                    continue;
            if (page_allocated) {
  
  

I'll post a patch if it looks ok.