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BUG: KCSAN: data-race in __jbd2_journal_drop_transaction / start_this_handle

write to 0xffff888102aa5878 of 8 bytes by task 18431 on cpu 1:
 jbd2_get_transaction fs/jbd2/transaction.c:125 [inline]
 start_this_handle+0xf1b/0x1250 fs/jbd2/transaction.c:416
 jbd2__journal_start+0x1fc/0x3b0 fs/jbd2/transaction.c:525
 __ext4_journal_start_sb+0x159/0x2d0 fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_dirty_inode+0x58/0xa0 fs/ext4/inode.c:5905
 __mark_inode_dirty+0x77/0x6a0 fs/fs-writeback.c:2398
 generic_update_time fs/inode.c:1776 [inline]
 update_time fs/inode.c:1789 [inline]
 file_update_time+0x3b5/0x3f0 fs/inode.c:2005
 ext4_page_mkwrite+0x11a/0xec0 fs/ext4/inode.c:6026
 do_page_mkwrite mm/memory.c:2870 [inline]
 do_shared_fault mm/memory.c:4237 [inline]
 do_fault mm/memory.c:4305 [inline]
 handle_pte_fault mm/memory.c:4559 [inline]
 __handle_mm_fault mm/memory.c:4694 [inline]
 handle_mm_fault+0xd9c/0x1580 mm/memory.c:4792
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1485 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1541
 asm_exc_page_fault+0x1e/0x30

read to 0xffff888102aa5878 of 8 bytes by task 345 on cpu 0:
 __jbd2_journal_drop_transaction+0x1f0/0x2c0 fs/jbd2/checkpoint.c:803
 __jbd2_journal_remove_checkpoint+0x2d5/0x370 fs/jbd2/checkpoint.c:734
 jbd2_journal_commit_transaction+0x246e/0x3430 fs/jbd2/commit.c:1019
 kjournald2+0x268/0x490 fs/jbd2/journal.c:213
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

value changed: 0x0000000000000000 -> 0xffff8881370cda00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 345 Comm: jbd2/sda1-8 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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