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BUG: KCSAN: data-race in mb_mark_used / mb_update_avg_fragment_size

write to 0xffff8881018ce858 of 4 bytes by task 20181 on cpu 0:
 mb_mark_used+0x2f2/0xc50 fs/ext4/mballoc.c:1959
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_measure_extent fs/ext4/mballoc.c:2091 [inline]
 ext4_mb_complex_scan_group+0x55d/0x850 fs/ext4/mballoc.c:2365
 ext4_mb_regular_allocator+0x1a22/0x2520 fs/ext4/mballoc.c:2778
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5586
 ext4_ext_map_blocks+0x1579/0x1f10 fs/ext4/extents.c:4250
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:637
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4437
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4718
 vfs_fallocate+0x459/0x6a0 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 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 0xffff8881018ce858 of 4 bytes by task 19162 on cpu 1:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:838 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:815 [inline]
 mb_update_avg_fragment_size+0x161/0x260 fs/ext4/mballoc.c:863
 mb_free_blocks+0x9e4/0xb40 fs/ext4/mballoc.c:1860
 ext4_free_blocks+0x1448/0x1b80 fs/ext4/mballoc.c:6061
 ext4_remove_blocks+0x61a/0x800 fs/ext4/extents.c:2506
 ext4_ext_rm_leaf+0x684/0xd40 fs/ext4/extents.c:2672
 ext4_ext_remove_space+0x8d6/0x1290 fs/ext4/extents.c:2920
 ext4_ext_truncate+0xfe/0x170 fs/ext4/extents.c:4382
 ext4_truncate+0x76e/0xa80 fs/ext4/inode.c:4268
 ext4_evict_inode+0xa54/0xdb0 fs/ext4/inode.c:287
 evict+0x1c8/0x3c0 fs/inode.c:586
 iput_final fs/inode.c:1662 [inline]
 iput+0x430/0x580 fs/inode.c:1688
 dentry_unlink_inode+0x273/0x290 fs/dcache.c:376
 d_delete+0x78/0xe0 fs/dcache.c:2505
 vfs_rmdir+0x2e6/0x300 fs/namei.c:3984
 do_rmdir+0x15d/0x310 fs/namei.c:4032
 __do_sys_rmdir fs/namei.c:4051 [inline]
 __se_sys_rmdir fs/namei.c:4049 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:4049
 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: 0x0000000e -> 0x0000000d

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19162 Comm: syz-executor.3 Tainted: G        W         5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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