loop4: detected capacity change from 0 to 131456
==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

write to 0xffffffff8455f74c of 4 bytes by task 10961 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:559 [inline]
 pcpu_block_update_hint_free mm/percpu.c:994 [inline]
 pcpu_free_area+0x50c/0x5a0 mm/percpu.c:1254
 free_percpu+0x1d2/0x690 mm/percpu.c:2102
 ext4_mb_release+0x73e/0x770 fs/ext4/mballoc.c:3529
 ext4_put_super+0x2b4/0x8e0 fs/ext4/super.c:1188
 generic_shutdown_super+0xe1/0x230 fs/super.c:465
 kill_block_super+0x4a/0x90 fs/super.c:1395
 deactivate_locked_super+0x65/0xd0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x267/0x2d0 fs/namespace.c:1136
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1143
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8455f74c of 4 bytes by task 6033 on cpu 1:
 pcpu_alloc+0xa33/0x1200 mm/percpu.c:1835
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1894
 __percpu_counter_init+0x43/0x130 lib/percpu_counter.c:149
 ext4_es_register_shrinker+0xba/0x1f0 fs/ext4/extents_status.c:1643
 ext4_fill_super+0x4392/0x8010 fs/ext4/super.c:4723
 mount_bdev+0x1e8/0x290 fs/super.c:1368
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6632
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1498
 do_new_mount fs/namespace.c:2905 [inline]
 path_mount+0x11d4/0x1ce0 fs/namespace.c:3235
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6033 Comm: syz-executor.4 Tainted: G        W         5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
[EXT4 FS bs=1024, gc=1, bpg=8192, ipg=32, mo=a000c018, mo2=0006]
System zones: 1-2, 19-19, 35-38, 46-46
EXT4-fs (loop4): mounted filesystem without journal. Opts: ,errors=continue. Quota mode: none.
ext4 filesystem being mounted at /root/syzkaller-testdir215470347/syzkaller.7HGlxx/1684/file0 supports timestamps until 2038 (0x7fffffff)