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BUG: KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

write to 0xffff8881017fa6d8 of 4 bytes by task 16208 on cpu 1:
 mb_free_blocks+0x323/0xb40 fs/ext4/mballoc.c:1833
 ext4_trim_extent+0x2bc/0x410 fs/ext4/mballoc.c:6217
 ext4_trim_all_free+0x398/0x8a0 fs/ext4/mballoc.c:6274
 ext4_trim_fs+0x3f3/0x520 fs/ext4/mballoc.c:6380
 __ext4_ioctl fs/ext4/ioctl.c:1122 [inline]
 ext4_ioctl+0xf90/0x2100 fs/ext4/ioctl.c:1277
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/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

read to 0xffff8881017fa6d8 of 4 bytes by task 16206 on cpu 0:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:834 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:811 [inline]
 mb_update_avg_fragment_size+0x161/0x260 fs/ext4/mballoc.c:859
 mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1994
 ext4_trim_extent+0xb8/0x410 fs/ext4/mballoc.c:6213
 ext4_trim_all_free+0x398/0x8a0 fs/ext4/mballoc.c:6274
 ext4_trim_fs+0x3f3/0x520 fs/ext4/mballoc.c:6380
 __ext4_ioctl fs/ext4/ioctl.c:1122 [inline]
 ext4_ioctl+0xf90/0x2100 fs/ext4/ioctl.c:1277
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/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: 0x00000009 -> 0x0000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16206 Comm: syz-executor.3 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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