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BUG: KCSAN: data-race in mb_mark_used / mb_update_avg_fragment_size

write to 0xffff8881010c8b54 of 4 bytes by task 749 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_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_zero_range+0x348/0xa80 fs/ext4/extents.c:4550
 ext4_fallocate+0x226/0x4d0 fs/ext4/extents.c:4687
 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 0xffff8881010c8b54 of 4 bytes by task 773 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_free_blocks+0x9e4/0xb40 fs/ext4/mballoc.c:1860
 ext4_free_blocks+0x14ea/0x1c20 fs/ext4/mballoc.c:6061
 ext4_free_branches+0x320/0x440 fs/ext4/indirect.c:1075
 ext4_ind_truncate+0x807/0x8c0 fs/ext4/indirect.c:1193
 ext4_truncate+0x756/0xa80 fs/ext4/inode.c:4270
 ext4_truncate_failed_write fs/ext4/truncate.h:22 [inline]
 ext4_handle_inode_extension fs/ext4/file.c:358 [inline]
 ext4_dio_write_iter fs/ext4/file.c:574 [inline]
 ext4_file_write_iter+0xf77/0x11f0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2163 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:729
 do_iter_write+0x192/0x5c0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x202/0x3c0 fs/read_write.c:1025
 __do_sys_pwritev fs/read_write.c:1072 [inline]
 __se_sys_pwritev fs/read_write.c:1067 [inline]
 __x64_sys_pwritev+0x54/0x60 fs/read_write.c:1067
 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: 0x00000234 -> 0x0000022d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 773 Comm: syz-executor.2 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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