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BUG: KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

write to 0xffff888101790494 of 4 bytes by task 6511 on cpu 0:
 mb_free_blocks+0x156/0xb40 fs/ext4/mballoc.c:1798
 ext4_free_blocks+0x1418/0x1b50 fs/ext4/mballoc.c:5989
 ext4_remove_blocks+0x61a/0x800 fs/ext4/extents.c:2502
 ext4_ext_rm_leaf+0x670/0xd20 fs/ext4/extents.c:2668
 ext4_ext_remove_space+0x901/0x1300 fs/ext4/extents.c:2916
 ext4_ext_truncate+0xfe/0x170 fs/ext4/extents.c:4377
 ext4_truncate+0x76e/0xa80 fs/ext4/inode.c:4262
 ext4_setattr+0xacc/0xec0 fs/ext4/inode.c:5504
 notify_change+0x8a3/0xa80 fs/attr.c:398
 do_truncate+0xe8/0x130 fs/open.c:64
 handle_truncate fs/namei.c:3030 [inline]
 do_open fs/namei.c:3378 [inline]
 path_openat+0x19b2/0x1f20 fs/namei.c:3507
 do_filp_open+0xe9/0x200 fs/namei.c:3534
 do_sys_openat2+0xa3/0x250 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_creat fs/open.c:1294 [inline]
 __se_sys_creat fs/open.c:1288 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1288
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101790494 of 4 bytes by task 6512 on cpu 1:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:835 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:811 [inline]
 mb_update_avg_fragment_size+0x184/0x260 fs/ext4/mballoc.c:859
 mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1994
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2015
 ext4_mb_find_by_goal+0x5c3/0x890 fs/ext4/mballoc.c:2227
 ext4_mb_regular_allocator+0x11c/0x2520 fs/ext4/mballoc.c:2636
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5515
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4712
 vfs_fallocate+0x463/0x660 fs/open.c:311
 file_ioctl fs/ioctl.c:497 [inline]
 do_vfs_ioctl+0x1322/0x1410 fs/ioctl.c:1048
 __do_sys_ioctl fs/ioctl.c:1067 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000006fd -> 0x000007fe

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6512 Comm: syz-executor.4 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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