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BUG: KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks

write to 0xffff8881013dd6d4 of 4 bytes by task 1402 on cpu 0:
 mb_free_blocks+0x156/0xb40 fs/ext4/mballoc.c:1802
 ext4_free_data_in_buddy fs/ext4/mballoc.c:3662 [inline]
 ext4_process_freed_data+0x488/0x900 fs/ext4/mballoc.c:3713
 ext4_journal_commit_callback+0x83/0x1a0 fs/ext4/super.c:449
 jbd2_journal_commit_transaction+0x2b1f/0x3460 fs/jbd2/commit.c:1171
 kjournald2+0x263/0x480 fs/jbd2/journal.c:213
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff8881013dd6d4 of 4 bytes by task 5667 on cpu 1:
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2504 [inline]
 ext4_mb_regular_allocator+0xa97/0x24a0 fs/ext4/mballoc.c:2747
 ext4_mb_new_blocks+0x78c/0x1ee0 fs/ext4/mballoc.c:5586
 ext4_ext_map_blocks+0x1658/0x2120 fs/ext4/extents.c:4285
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 ext4_alloc_file_blocks+0x281/0x730 fs/ext4/extents.c:4472
 ext4_fallocate+0x2a7/0x540 fs/ext4/extents.c:4753
 vfs_fallocate+0x486/0x720 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+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000 -> 0x00000fff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5667 Comm: syz-executor.5 Not tainted 5.16.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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