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authorMiaohe Lin2021-06-28 19:36:57 -0700
committerLinus Torvalds2021-06-29 10:53:49 -0700
commit2efa33fc7f6ec94a3a538c1a264273c889be2b36 (patch)
tree157a2f728b920ea9b66548012371f74e2ad590cd /mm/shmem.c
parent5c046235a826370d528a29c44e0ce05f9685d8b4 (diff)
mm/shmem: fix shmem_swapin() race with swapoff
When I was investigating the swap code, I found the below possible race window: CPU 1 CPU 2 ----- ----- shmem_swapin swap_cluster_readahead if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) { swapoff .. si->swap_file = NULL; .. struct inode *inode = si->swap_file->f_mapping->host;[oops!] Close this race window by using get/put_swap_device() to guard against concurrent swapoff. Link: https://lkml.kernel.org/r/20210426123316.806267-5-linmiaohe@huawei.com Fixes: 8fd2e0b505d1 ("mm: swap: check if swap backing device is congested or not") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alex Shi <alexs@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <shy828301@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 5d46611cba8d..53f21016608e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1696,7 +1696,8 @@ 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 page *page;
+ struct swap_info_struct *si;
+ struct page *page = NULL;
swp_entry_t swap;
int error;
@@ -1704,6 +1705,12 @@ 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) {
@@ -1765,6 +1772,8 @@ 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))
@@ -1775,6 +1784,9 @@ unlock:
put_page(page);
}
+ if (si)
+ put_swap_device(si);
+
return error;
}