Revert "mm/shmem: fix shmem_swapin() race with swapoff"

This reverts commit a533a21b692fc15a6aadfa827b29c7d9989109ca which is
commit 2efa33fc7f6ec94a3a538c1a264273c889be2b36 upstream.

It should not have been added to the stable trees, sorry about that.

Link: https://lore.kernel.org/r/YPVgaY6uw59Fqg5x@casper.infradead.org
Reported-by: From: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 96df61c..ae8adca 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1698,8 +1698,7 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
        struct address_space *mapping = inode->i_mapping;
        struct shmem_inode_info *info = SHMEM_I(inode);
        struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
-       struct swap_info_struct *si;
-       struct page *page = NULL;
+       struct page *page;
        swp_entry_t swap;
        int error;
 
@@ -1707,12 +1706,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
        swap = radix_to_swp_entry(*pagep);
        *pagep = NULL;
 
-       /* Prevent swapoff from happening to us. */
-       si = get_swap_device(swap);
-       if (!si) {
-               error = EINVAL;
-               goto failed;
-       }
        /* Look it up and read it in.. */
        page = lookup_swap_cache(swap, NULL, 0);
        if (!page) {
@@ -1774,8 +1767,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
        swap_free(swap);
 
        *pagep = page;
-       if (si)
-               put_swap_device(si);
        return 0;
 failed:
        if (!shmem_confirm_swap(mapping, index, swap))
@@ -1786,9 +1777,6 @@ unlock:
                put_page(page);
        }
 
-       if (si)
-               put_swap_device(si);
-
        return error;
 }