================================================================== BUG: KCSAN: data-race in caching_thread / find_free_extent write to 0xffff88810d7ab4a4 of 4 bytes by task 7 on cpu 0: caching_thread+0x691/0x7c0 fs/btrfs/block-group.c:649 btrfs_work_helper+0x1e2/0x380 fs/btrfs/async-thread.c:318 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272 worker_thread+0x635/0xb90 kernel/workqueue.c:2418 kthread+0x1fa/0x220 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 read to 0xffff88810d7ab4a4 of 4 bytes by task 8452 on cpu 1: find_free_extent+0xf51/0x1a30 fs/btrfs/extent-tree.c:4224 btrfs_reserve_extent+0x118/0x2c0 fs/btrfs/extent-tree.c:4358 btrfs_alloc_tree_block+0x101/0x7f0 fs/btrfs/extent-tree.c:4757 alloc_tree_block_no_bg_flush fs/btrfs/ctree.c:989 [inline] __btrfs_cow_block+0x2ea/0xa40 fs/btrfs/ctree.c:1045 btrfs_cow_block+0x268/0x3b0 fs/btrfs/ctree.c:1497 commit_cowonly_roots+0x91/0x5d0 fs/btrfs/transaction.c:1186 btrfs_commit_transaction+0xaee/0x1910 fs/btrfs/transaction.c:2283 btrfs_commit_super+0x8f/0xa0 fs/btrfs/disk-io.c:3964 close_ctree+0x1af/0x49b fs/btrfs/disk-io.c:4028 btrfs_put_super+0x21/0x30 fs/btrfs/super.c:321 generic_shutdown_super+0xcd/0x1f0 fs/super.c:464 kill_anon_super+0x23/0x40 fs/super.c:1108 btrfs_kill_super+0x26/0x40 fs/btrfs/super.c:2263 deactivate_locked_super+0x6a/0xb0 fs/super.c:335 deactivate_super+0x85/0x90 fs/super.c:366 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125 task_work_run+0x8e/0x110 kernel/task_work.c:151 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:164 [inline] exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 8452 Comm: syz-executor.1 Not tainted 5.10.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================