CIFS corrupts ext4 FS inside an image mounted on loop

I have a CIFS volume which contains an image file formatted with ext4 and mounted on loop. Sometimes the ext4 FS corrupt itself and the following lines shows in the logs:

Jan 30 04:00:02 server1 kernel: [817452.247111] CIFS: Attempting to mount //IP/FOLDER
Jan 30 04:00:08 server1 kernel: [817458.303566] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
Jan 30 04:27:22 server1 kernel: [819092.088384] loop0: page allocation failure: order:4, mode:0x40c00(GFP_NOIO|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0
Jan 30 04:27:22 server1 kernel: [819092.088424] CPU: 6 PID: 844940 Comm: loop0 Not tainted 5.4.0-137-generic #154-Ubuntu
Jan 30 04:27:22 server1 kernel: [819092.088426] Hardware name: vServer, BIOS 20171111 11/11/2017
Jan 30 04:27:22 server1 kernel: [819092.088435] Call Trace:
Jan 30 04:27:22 server1 kernel: [819092.088478]  dump_stack+0x6d/0x8b
Jan 30 04:27:22 server1 kernel: [819092.088484]  warn_alloc.cold+0x7b/0xdf
Jan 30 04:27:22 server1 kernel: [819092.088493]  __alloc_pages_slowpath+0xe6e/0xeb0
Jan 30 04:27:22 server1 kernel: [819092.088504]  ? get_page_from_freelist+0x195/0x3f0
Jan 30 04:27:22 server1 kernel: [819092.088509]  __alloc_pages_nodemask+0x2d0/0x320
Jan 30 04:27:22 server1 kernel: [819092.088515]  alloc_pages_current+0x87/0xe0
Jan 30 04:27:22 server1 kernel: [819092.088522]  kmalloc_order+0x1f/0x80
Jan 30 04:27:22 server1 kernel: [819092.088526]  kmalloc_order_trace+0x24/0xa0
Jan 30 04:27:22 server1 kernel: [819092.088531]  __kmalloc+0x22b/0x290
Jan 30 04:27:22 server1 kernel: [819092.088663]  crypt_message+0x378/0x870 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088669]  ? _get_random_bytes.part.0+0x52/0x190
Jan 30 04:27:22 server1 kernel: [819092.088714]  smb3_init_transform_rq+0x277/0x300 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088754]  smb_send_rqst+0xe9/0x1a0 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088794]  cifs_call_async+0x11e/0x270 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088835]  ? smb311_decode_neg_context+0x460/0x460 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088877]  smb2_async_writev+0x25e/0x500 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088883]  ? __mod_lruvec_state+0x44/0xf0
Jan 30 04:27:22 server1 kernel: [819092.088907]  ? cifs_echo_callback+0x70/0x70 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088942]  cifs_writepages+0x8d8/0xd80 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088975]  ? cifs_writepages+0x8d8/0xd80 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.088987]  do_writepages+0x43/0xd0
Jan 30 04:27:22 server1 kernel: [819092.088997]  __filemap_fdatawrite_range+0xd5/0x110
Jan 30 04:27:22 server1 kernel: [819092.089006]  file_write_and_wait_range+0x74/0xc0
Jan 30 04:27:22 server1 kernel: [819092.089055]  cifs_strict_fsync+0x3b/0x440 [cifs]
Jan 30 04:27:22 server1 kernel: [819092.089066]  vfs_fsync_range+0x49/0x80
Jan 30 04:27:22 server1 kernel: [819092.089072]  vfs_fsync+0x1c/0x20
Jan 30 04:27:22 server1 kernel: [819092.089077]  loop_queue_work+0x267/0xac0
Jan 30 04:27:22 server1 kernel: [819092.089091]  ? __switch_to+0x7f/0x470
Jan 30 04:27:22 server1 kernel: [819092.089095]  ? __switch_to_asm+0x42/0x80
Jan 30 04:27:22 server1 kernel: [819092.089097]  ? __switch_to_asm+0x5a/0x80
Jan 30 04:27:22 server1 kernel: [819092.089107]  kthread_worker_fn+0x79/0x1d0
Jan 30 04:27:22 server1 kernel: [819092.089112]  loop_kthread_worker_fn+0x1e/0x20
Jan 30 04:27:22 server1 kernel: [819092.089116]  kthread+0x104/0x140
Jan 30 04:27:22 server1 kernel: [819092.089120]  ? loop_info64_to_compat+0x210/0x210
Jan 30 04:27:22 server1 kernel: [819092.089124]  ? kthread_park+0x90/0x90
Jan 30 04:27:22 server1 kernel: [819092.089127]  ret_from_fork+0x1f/0x40
Jan 30 04:27:22 server1 kernel: [819092.089133] Mem-Info:
[...]
Jan 30 04:27:22 server1 kernel: [819092.089304] CIFS VFS: \\IP crypt_message: Failed to init sg
Jan 30 04:27:23 server1 kernel: [819093.523678] blk_update_request: I/O error, dev loop0, sector 524599896 op 0x1:(WRITE) flags 0x800 phys_seg 1 prio class 0
Jan 30 04:27:23 server1 kernel: [819093.546727] Aborting journal on device loop0-8.
Jan 30 04:27:27 server1 kernel: [819096.939360] EXT4-fs error (device loop0): ext4_journal_check_start:61: Detected aborted journal
Jan 30 04:27:27 server1 kernel: [819096.943587] EXT4-fs (loop0): Remounting filesystem read-only
Jan 30 04:27:27 server1 kernel: [819096.946172] EXT4-fs (loop0): ext4_writepages: jbd2_start: 4096 pages, ino 29231359; err -30

Is there a bug in the kernel or is the problem elsewhere?