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BUG: KCSAN: data-race in ext4_mb_good_group / mb_free_blocks

read-write to 0xffff888141721014 of 4 bytes by task 9736 on cpu 1:
 mb_free_blocks+0x13d/0xe00 fs/ext4/mballoc.c:1486
 ext4_free_blocks+0x13b2/0x1c80 fs/ext4/mballoc.c:5470
 ext4_remove_blocks+0x7d5/0x9e0 fs/ext4/extents.c:2498
 ext4_ext_rm_leaf+0x69e/0xe60 fs/ext4/extents.c:2664
 ext4_ext_remove_space+0x936/0x13e0 fs/ext4/extents.c:2912
 ext4_ext_truncate+0xf9/0x160 fs/ext4/extents.c:4370
 ext4_truncate+0x82b/0xbb0 fs/ext4/inode.c:4254
 ext4_evict_inode+0xa5e/0xe70 fs/ext4/inode.c:280
 evict+0x19f/0x470 fs/inode.c:578
 iput_final fs/inode.c:1654 [inline]
 iput+0x421/0x510 fs/inode.c:1680
 dentry_unlink_inode+0x1f3/0x210 fs/dcache.c:374
 __dentry_kill+0x28b/0x450 fs/dcache.c:579
 dentry_kill fs/dcache.c:692 [inline]
 dput+0x203/0x420 fs/dcache.c:878
 cleanup_mnt+0x265/0x2e0 fs/namespace.c:1117
 __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

read to 0xffff888141721014 of 4 bytes by task 17018 on cpu 0:
 ext4_mb_good_group+0x11c/0x350 fs/ext4/mballoc.c:2114
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2213 [inline]
 ext4_mb_regular_allocator+0xc6f/0x18a0 fs/ext4/mballoc.c:2409
 ext4_mb_new_blocks+0x6e8/0x1140 fs/ext4/mballoc.c:4997
 ext4_ext_map_blocks+0x15a0/0x1fc0 fs/ext4/extents.c:4238
 ext4_map_blocks+0x700/0xfc0 fs/ext4/inode.c:628
 ext4_getblk+0xb1/0x350 fs/ext4/inode.c:838
 ext4_bread+0x28/0x130 fs/ext4/inode.c:890
 ext4_append+0xd1/0x1b0 fs/ext4/namei.c:67
 ext4_init_new_dir+0x177/0x500 fs/ext4/namei.c:2764
 ext4_mkdir+0x319/0x730 fs/ext4/namei.c:2809
 vfs_mkdir+0x288/0x350 fs/namei.c:3650
 do_mkdirat+0x132/0x220 fs/namei.c:3673
 __do_sys_mkdir fs/namei.c:3689 [inline]
 __se_sys_mkdir fs/namei.c:3687 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3687
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17018 Comm: syz-executor.3 Not tainted 5.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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