From: Domenico Andreoli <domenico.andreoli@xxxxxxxxx> It turns out that there is one use case for programs being able to write to swap devices, and that is the userspace hibernation code. Quick fix: disable the S_SWAPFILE check if hibernation is configured. Fixes: 1638045c3677 ("mm: set S_SWAPFILE on blockdev swap devices") Reported-by: Domenico Andreoli <domenico.andreoli@xxxxxxxxx> Reported-by: Marian Klein <mkleinsoft@xxxxxxxxx> Signed-off-by: Domenico Andreoli <domenico.andreoli@xxxxxxxxx> --- fs/block_dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) Index: b/fs/block_dev.c =================================================================== --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -2001,7 +2001,8 @@ ssize_t blkdev_write_iter(struct kiocb * if (bdev_read_only(I_BDEV(bd_inode))) return -EPERM; - if (IS_SWAPFILE(bd_inode)) + /* uswsusp needs to write to the swap */ + if (IS_SWAPFILE(bd_inode) && !IS_ENABLED(CONFIG_HIBERNATION)) return -ETXTBSY; if (!iov_iter_count(from))