linux-kernel - [PATCH 5.13 104/156] Revert "mm/shmem: fix shmem

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Date:   Thu, 22 Jul 2021 18:31:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "From: Matthew Wilcox" <willy@...radead.org>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Ying Huang <ying.huang@...el.com>, Alex Shi <alexs@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Dennis Zhou <dennis@...nel.org>,
        Hugh Dickins <hughd@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Michal Hocko <mhocko@...e.com>,
        Minchan Kim <minchan@...nel.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Wei Yang <richard.weiyang@...il.com>,
        Yang Shi <shy828301@...il.com>, Yu Zhao <yuzhao@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 104/156] Revert "mm/shmem: fix shmem_swapin() race with swapoff"

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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@...radead.org>
Cc: Miaohe Lin <linmiaohe@...wei.com>
Cc: Ying Huang <ying.huang@...el.com>
Cc: Alex Shi <alexs@...nel.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Dennis Zhou <dennis@...nel.org>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Wei Yang <richard.weiyang@...il.com>
Cc: Yang Shi <shy828301@...il.com>
Cc: Yu Zhao <yuzhao@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Sasha Levin <sashal@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/shmem.c |   14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1696,8 +1696,7 @@ static int shmem_swapin_page(struct inod
 	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;
 
@@ -1705,12 +1704,6 @@ static int shmem_swapin_page(struct inod
 	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 inod
 	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 @@ unlock:
 		put_page(page);
 	}
 
-	if (si)
-		put_swap_device(si);
-
 	return error;
 }