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BUG: KCSAN: data-race in mb_mark_used / mb_update_avg_fragment_size

write to 0xffff88810108e018 of 4 bytes by task 22039 on cpu 1:
 mb_mark_used+0x2f2/0xc50
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_complex_scan_group+0x57d/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
 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
 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+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810108e018 of 4 bytes by task 22041 on cpu 0:
 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_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1998
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
 ext4_mb_simple_scan_group+0x253/0x3a0 fs/ext4/mballoc.c:2297
 ext4_mb_regular_allocator+0x1984/0x2530 fs/ext4/mballoc.c:2773
 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
 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+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000002 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22041 Comm: syz-executor.4 Not tainted 5.15.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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