diff options
| -rw-r--r-- | mm/shmem.c | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 4ea6109a8043..cebbac97a221 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2253,7 +2253,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, struct folio *folio = NULL; bool skip_swapcache = false; swp_entry_t swap; - int error, nr_pages; + int error, nr_pages, order, split_order; VM_BUG_ON(!*foliop || !xa_is_value(*foliop)); swap = radix_to_swp_entry(*foliop); @@ -2272,10 +2272,9 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, /* Look it up and read it in.. */ folio = swap_cache_get_folio(swap, NULL, 0); + order = xa_get_order(&mapping->i_pages, index); if (!folio) { - int order = xa_get_order(&mapping->i_pages, index); bool fallback_order0 = false; - int split_order; /* Or update major stats only when swapin succeeds?? */ if (fault_type) { @@ -2339,6 +2338,29 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, error = -ENOMEM; goto failed; } + } else if (order != folio_order(folio)) { + /* + * Swap readahead may swap in order 0 folios into swapcache + * asynchronously, while the shmem mapping can still stores + * large swap entries. In such cases, we should split the + * large swap entry to prevent possible data corruption. + */ + split_order = shmem_split_large_entry(inode, index, swap, gfp); + if (split_order < 0) { + error = split_order; + goto failed; + } + + /* + * If the large swap entry has already been split, it is + * necessary to recalculate the new swap entry based on + * the old order alignment. + */ + if (split_order > 0) { + pgoff_t offset = index - round_down(index, 1 << split_order); + + swap = swp_entry(swp_type(swap), swp_offset(swap) + offset); + } } alloced: @@ -2346,7 +2368,8 @@ alloced: folio_lock(folio); if ((!skip_swapcache && !folio_test_swapcache(folio)) || folio->swap.val != swap.val || - !shmem_confirm_swap(mapping, index, swap)) { + !shmem_confirm_swap(mapping, index, swap) || + xa_get_order(&mapping->i_pages, index) != folio_order(folio)) { error = -EEXIST; goto unlock; } |