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BUG: KCSAN: data-race in ext4_mb_regular_allocator / mb_mark_used

write to 0xffff88821aab2014 of 4 bytes by task 8866 on cpu 0:
 mb_mark_used+0x135/0xba0 fs/ext4/mballoc.c:1637
 ext4_mb_use_best_found+0x102/0x2f0 fs/ext4/mballoc.c:1708
 ext4_mb_measure_extent fs/ext4/mballoc.c:1827 [inline]
 ext4_mb_complex_scan_group+0x345/0x820 fs/ext4/mballoc.c:2058
 ext4_mb_regular_allocator+0xc4a/0xf90 fs/ext4/mballoc.c:2328
 ext4_mb_new_blocks+0x304/0xcf0 fs/ext4/mballoc.c:4721
 ext4_ext_map_blocks+0x164e/0x20c0 fs/ext4/extents.c:4244
 ext4_map_blocks+0x6a6/0xf60 fs/ext4/inode.c:626
 ext4_getblk+0x67/0x2c0 fs/ext4/inode.c:833
 ext4_bread+0x3a/0x190 fs/ext4/inode.c:883
 ext4_append+0xda/0x1c0 fs/ext4/namei.c:67
 ext4_init_new_dir fs/ext4/namei.c:2757 [inline]
 ext4_mkdir+0x480/0xc00 fs/ext4/namei.c:2802
 vfs_mkdir+0x288/0x370 fs/namei.c:3641
 do_mkdirat+0x132/0x220 fs/namei.c:3664
 __do_sys_mkdir fs/namei.c:3680 [inline]
 __se_sys_mkdir fs/namei.c:3678 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3678
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88821aab2014 of 4 bytes by task 31018 on cpu 1:
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2186 [inline]
 ext4_mb_regular_allocator+0x67e/0xf90 fs/ext4/mballoc.c:2297
 ext4_mb_new_blocks+0x304/0xcf0 fs/ext4/mballoc.c:4721
 ext4_ext_map_blocks+0x164e/0x20c0 fs/ext4/extents.c:4244
 ext4_map_blocks+0x6a6/0xf60 fs/ext4/inode.c:626
 ext4_getblk+0x67/0x2c0 fs/ext4/inode.c:833
 ext4_bread+0x3a/0x190 fs/ext4/inode.c:883
 ext4_append+0xda/0x1c0 fs/ext4/namei.c:67
 ext4_init_new_dir fs/ext4/namei.c:2757 [inline]
 ext4_mkdir+0x480/0xc00 fs/ext4/namei.c:2802
 vfs_mkdir+0x288/0x370 fs/namei.c:3641
 do_mkdirat+0x132/0x220 fs/namei.c:3664
 __do_sys_mkdir fs/namei.c:3680 [inline]
 __se_sys_mkdir fs/namei.c:3678 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3678
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31018 Comm: syz-executor.1 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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