From b1e1ef345433fb03742003677ddfb980d148092b Mon Sep 17 00:00:00 2001
From: Yang Shi <shy828301@gmail.com>
Date: Thu, 19 Aug 2021 19:04:05 -0700
Subject: [PATCH] Revert "mm/shmem: fix shmem_swapin() race with swapoff"
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"), so the
fix commit could be just reverted as well.
And that fix is also kind of buggy as discussed by [1] and [2].
[1] https://lore.kernel.org/linux-mm/24187e5e-069-9f3f-cefe-39ac70783753@google.com/
[2] https://lore.kernel.org/linux-mm/e82380b9-3ad4-4a52-be50-6d45c7f2b5da@google.com/
Link: https://lkml.kernel.org/r/20210810202936.2672-2-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: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/shmem.c | 14 +-------------
1 file changed, 1 insertion(+), 13 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 70d9ce294bb49..dacda7463d549 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1696,8 +1696,7 @@ 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 : NULL;
- struct swap_info_struct *si;
- struct page *page = NULL;
+ struct page *page;
swp_entry_t swap;
int error;
@@ -1705,12 +1704,6 @@ 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) {
@@ -1772,8 +1765,6 @@ 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))
@@ -1784,9 +1775,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
put_page(page);
}
- if (si)
- put_swap_device(si);
-
return error;
}
--
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