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BUG: KCSAN: data-race in mb_mark_used / mb_update_avg_fragment_size

write to 0xffff8881010d99d4 of 4 bytes by task 5506 on cpu 1:
 mb_mark_used+0x13b/0xc50 fs/ext4/mballoc.c:1947
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_measure_extent fs/ext4/mballoc.c:2135 [inline]
 ext4_mb_complex_scan_group+0x359/0x880 fs/ext4/mballoc.c:2365
 ext4_mb_regular_allocator+0x1a32/0x2530 fs/ext4/mballoc.c:2778
 ext4_mb_new_blocks+0x792/0x1fc0 fs/ext4/mballoc.c:5586
 ext4_ext_map_blocks+0x15ed/0x1ff0 fs/ext4/extents.c:4250
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 mpage_map_one_extent+0x10d/0x360 fs/ext4/inode.c:2401
 mpage_map_and_submit_extent fs/ext4/inode.c:2454 [inline]
 ext4_writepages+0xc5a/0x1d70 fs/ext4/inode.c:2806
 do_writepages+0x26b/0x3c0 mm/page-writeback.c:2364
 __writeback_single_inode+0x80/0x440 fs/fs-writeback.c:1616
 writeback_sb_inodes+0x563/0xd30 fs/fs-writeback.c:1881
 wb_writeback+0x27d/0x6d0 fs/fs-writeback.c:2053
 wb_do_writeback+0x101/0x530 fs/fs-writeback.c:2196
 wb_workfn+0xc8/0x540 fs/fs-writeback.c:2237
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffff8881010d99d4 of 4 bytes by task 12969 on cpu 0:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:839 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:815 [inline]
 mb_update_avg_fragment_size+0x184/0x260 fs/ext4/mballoc.c:863
 mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1998
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_try_best_found+0x234/0x3d0 fs/ext4/mballoc.c:2185
 ext4_mb_regular_allocator+0x22cd/0x2530 fs/ext4/mballoc.c:2797
 ext4_mb_new_blocks+0x792/0x1fc0 fs/ext4/mballoc.c:5586
 ext4_ext_map_blocks+0x15ed/0x1ff0 fs/ext4/extents.c:4250
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 ext4_alloc_file_blocks+0x281/0x730 fs/ext4/extents.c:4437
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4718
 vfs_fallocate+0x459/0x6a0 fs/open.c:307
 do_vfs_ioctl+0x13c6/0x14c0 fs/ioctl.c:853
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000163 -> 0x00000160

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12969 Comm: syz-executor.2 Not tainted 5.15.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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