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BUG: KCSAN: data-race in start_this_handle / start_this_handle

write to 0xffff888144385870 of 8 bytes by task 22688 on cpu 1:
 jbd2_get_transaction fs/jbd2/transaction.c:125 [inline]
 start_this_handle+0xceb/0x1010 fs/jbd2/transaction.c:400
 jbd2__journal_start+0x1fc/0x3f0 fs/jbd2/transaction.c:503
 __ext4_journal_start_sb+0x154/0x310 fs/ext4/ext4_jbd2.c:105
 __ext4_new_inode+0xc57/0x3020 fs/ext4/ialloc.c:1076
 ext4_symlink+0x2c2/0x780 fs/ext4/namei.c:3336
 vfs_symlink+0x216/0x2d0 fs/namei.c:3962
 do_symlinkat+0xee/0x280 fs/namei.c:3989
 __do_sys_symlink fs/namei.c:4008 [inline]
 __se_sys_symlink fs/namei.c:4006 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4006
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888144385870 of 8 bytes by task 22675 on cpu 0:
 start_this_handle+0x1c1/0x1010 fs/jbd2/transaction.c:352
 jbd2__journal_start+0x1fc/0x3f0 fs/jbd2/transaction.c:503
 __ext4_journal_start_sb+0x154/0x310 fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start fs/ext4/ext4_jbd2.h:320 [inline]
 ext4_da_write_begin+0x46e/0xaa0 fs/ext4/inode.c:2997
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3408
 ext4_buffered_write_iter+0x2e5/0x3e0 fs/ext4/file.c:270
 ext4_file_write_iter+0x47a/0x1060 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f0/0x7e0 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+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22675 Comm: syz-executor.3 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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