loop1: detected capacity change from 0 to 530
==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

write to 0xffffffff8454374c of 4 bytes by task 17296 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:559 [inline]
 pcpu_block_update_hint_free mm/percpu.c:994 [inline]
 pcpu_free_area+0x531/0x5e0 mm/percpu.c:1254
 free_percpu+0x1d2/0x690 mm/percpu.c:2102
 perf_trace_event_unreg+0x193/0x1d0 kernel/trace/trace_event_perf.c:175
 perf_trace_destroy+0x59/0x70 kernel/trace/trace_event_perf.c:243
 tp_perf_event_destroy+0x11/0x20 kernel/events/core.c:9587
 _free_event+0x7db/0x9a0 kernel/events/core.c:4863
 put_event kernel/events/core.c:4957 [inline]
 perf_event_release_kernel+0x98c/0xa00 kernel/events/core.c:5072
 perf_release+0x21/0x30 kernel/events/core.c:5082
 __fput+0x25b/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:140
 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+0x151/0x170 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+0x40/0x50 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff8454374c of 4 bytes by task 17257 on cpu 0:
 pcpu_alloc+0x9d6/0x1170 mm/percpu.c:1835
 __alloc_percpu+0x20/0x30 mm/percpu.c:1907
 __percpu_init_rwsem+0x15/0x80 kernel/locking/percpu-rwsem.c:15
 alloc_super+0x13e/0x520 fs/super.c:235
 sget+0x1a5/0x400 fs/super.c:613
 mount_bdev+0xd3/0x290 fs/super.c:1340
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6605
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2903 [inline]
 path_mount+0x11d6/0x1ce0 fs/namespace.c:3233
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17257 Comm: syz-executor.1 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs: failed to create workqueue
EXT4-fs (loop1): mount failed