Revert "mm: swap: check if swap backing device is congested or not"

Due to the change about how block layer detects congestion the
justification of commit 8fd2e0b505d1 ("mm: swap: check if swap backing
device is congested or not") doesn't stand anymore, so the commit could
be just reverted in order to solve the race reported by commit
2efa33fc7f6e ("mm/shmem: fix shmem_swapin() race with swapoff").  The
fix was reverted by the previous patch.

Link: https://lkml.kernel.org/r/20210810202936.2672-3-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/swap_state.c b/mm/swap_state.c
index c56aa9a..bc7cee6 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -628,13 +628,6 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
        if (!mask)
                goto skip;
 
-       /* Test swap type to make sure the dereference is safe */
-       if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) {
-               struct inode *inode = si->swap_file->f_mapping->host;
-               if (inode_read_congested(inode))
-                       goto skip;
-       }
-
        do_poll = false;
        /* Read a page_cluster sized and aligned cluster around offset. */
        start_offset = offset & ~mask;