mm/shmem: fix shmem folio swapoff hang

Shmem swapoff makes no progress: the index to indices is not incremented.
But "ret" is no longer a return value, so use folio_batch_count() instead.

Link: https://lkml.kernel.org/r/c32bee8a-f0aa-245-f94e-24dd271924fa@google.com
Fixes: da08e9b79323 ("mm/shmem: convert shmem_swapin_page() to shmem_swapin_folio()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 7f41a24..b8169be 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1164,7 +1164,6 @@ static int shmem_find_swap_entries(struct address_space *mapping,
        XA_STATE(xas, &mapping->i_pages, start);
        struct folio *folio;
        swp_entry_t entry;
-       unsigned int ret = 0;
 
        rcu_read_lock();
        xas_for_each(&xas, folio, ULONG_MAX) {
@@ -1178,7 +1177,7 @@ static int shmem_find_swap_entries(struct address_space *mapping,
                if (swp_type(entry) != type)
                        continue;
 
-               indices[ret] = xas.xa_index;
+               indices[folio_batch_count(fbatch)] = xas.xa_index;
                if (!folio_batch_add(fbatch, folio))
                        break;