[02/10] Revert "mm: swap: check if swap backing device is congested or not"

Commit Message

Andrew Morton Aug. 20, 2021, 2:04 a.m. UTC

From: Yang Shi <[e-mail]>
Subject: 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/[e-mail]
Signed-off-by: Yang Shi <[e-mail]>
Suggested-by: Hugh Dickins <[e-mail]>
Acked-by: Hugh Dickins <[e-mail]>
Cc: "Huang, Ying" <[e-mail]>
Cc: Miaohe Lin <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Minchan Kim <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/swap_state.c |    7 -------
 1 file changed, 7 deletions(-)

Patch

--- a/mm/swap_state.c~revert-mm-swap-check-if-swap-backing-device-is-congested-or-not
+++ a/mm/swap_state.c
@@ -628,13 +628,6 @@  struct page *swap_cluster_readahead(swp_
 	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;