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BUG: KCSAN: data-race in __ext4_journal_start_sb / jbd2_journal_commit_transaction

write to 0xffff8881448d9000 of 8 bytes by task 4812 on cpu 1:
 jbd2_journal_commit_transaction+0x228/0x3290 fs/jbd2/commit.c:443
 kjournald2+0x263/0x480 fs/jbd2/journal.c:213
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff8881448d9000 of 8 bytes by task 7995 on cpu 0:
 is_journal_aborted include/linux/jbd2.h:1647 [inline]
 ext4_journal_check_start fs/ext4/ext4_jbd2.c:82 [inline]
 __ext4_journal_start_sb+0xf2/0x310 fs/ext4/ext4_jbd2.c:98
 __ext4_journal_start fs/ext4/ext4_jbd2.h:320 [inline]
 ext4_dirty_inode+0x58/0xa0 fs/ext4/inode.c:5944
 __mark_inode_dirty+0x72/0x6f0 fs/fs-writeback.c:2274
 mark_inode_dirty include/linux/fs.h:2267 [inline]
 generic_write_end+0x166/0x240 fs/buffer.c:2203
 ext4_da_write_end+0x59b/0x760 fs/ext4/inode.c:3112
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3586
 ext4_buffered_write_iter+0x2e5/0x3e0 fs/ext4/file.c:269
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f9/0x7e0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7995 Comm: rs:main Q:Reg Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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