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BUG: KCSAN: data-race in start_this_handle / start_this_handle

write to 0xffff8881442cf070 of 8 bytes by task 22284 on cpu 0:
 jbd2_get_transaction syzkaller/managers/upstream-kcsan-gce/kernel/fs/jbd2/transaction.c:125 [inline]
 start_this_handle+0xceb/0x1010 syzkaller/managers/upstream-kcsan-gce/kernel/fs/jbd2/transaction.c:400
 jbd2__journal_start+0x1fc/0x3f0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/jbd2/transaction.c:503
 __ext4_journal_start_sb+0x154/0x310 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/ext4_jbd2.h:320 [inline]
 ext4_handle_inode_extension+0x103/0x550 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:326
 ext4_dio_write_iter syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:558 [inline]
 ext4_file_write_iter+0xeaa/0x1060 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:662
 call_write_iter syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x2cb/0x360 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:740
 do_iter_write+0x112/0x4c0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:907
 iter_file_splice_write+0x41a/0x770 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:686
 do_splice_from syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:888
 do_splice_direct+0xf5/0x170 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1257
 __do_sys_sendfile64 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1304
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881442cf070 of 8 bytes by task 22289 on cpu 1:
 start_this_handle+0x1c1/0x1010 syzkaller/managers/upstream-kcsan-gce/kernel/fs/jbd2/transaction.c:352
 jbd2__journal_start+0x1fc/0x3f0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/jbd2/transaction.c:503
 __ext4_journal_start_sb+0x154/0x310 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/ext4_jbd2.h:320 [inline]
 ext4_dio_write_iter syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:533 [inline]
 ext4_file_write_iter+0xd5c/0x1060 syzkaller/managers/upstream-kcsan-gce/kernel/fs/ext4/file.c:662
 call_write_iter syzkaller/managers/upstream-kcsan-gce/kernel/./include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x2cb/0x360 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:740
 do_iter_write+0x112/0x4c0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:907
 iter_file_splice_write+0x41a/0x770 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:686
 do_splice_from syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:888
 do_splice_direct+0xf5/0x170 syzkaller/managers/upstream-kcsan-gce/kernel/fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1257
 __do_sys_sendfile64 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 syzkaller/managers/upstream-kcsan-gce/kernel/fs/read_write.c:1304
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22289 Comm: syz-executor.1 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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