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BUG: KCSAN: data-race in mm_update_next_owner / stop_this_handle

write to 0xffff88810252302c of 4 bytes by task 8374 on cpu 1:
 memalloc_nofs_restore include/linux/sched/mm.h:258 [inline]
 stop_this_handle+0x2ae/0x2f0 fs/jbd2/transaction.c:744
 jbd2_journal_stop+0x573/0x6d0 fs/jbd2/transaction.c:1907
 __ext4_journal_stop+0x99/0x110 fs/ext4/ext4_jbd2.c:127
 ext4_dirty_inode+0xba/0xc0 fs/ext4/inode.c:5957
 __mark_inode_dirty+0x72/0x6b0 fs/fs-writeback.c:2262
 generic_update_time fs/inode.c:1763 [inline]
 update_time fs/inode.c:1776 [inline]
 file_update_time+0x3ac/0x3f0 fs/inode.c:1991
 ext4_page_mkwrite+0x141/0xf40 fs/ext4/inode.c:6075
 do_page_mkwrite mm/memory.c:2714 [inline]
 wp_page_shared+0x2a7/0x7c0 mm/memory.c:3045
 do_wp_page+0x681/0x6d0 mm/memory.c:3138
 handle_pte_fault mm/memory.c:4405 [inline]
 __handle_mm_fault mm/memory.c:4522 [inline]
 handle_mm_fault+0x144d/0x1810 mm/memory.c:4620
 do_user_addr_fault+0x43e/0x830 arch/x86/mm/fault.c:1393
 handle_page_fault arch/x86/mm/fault.c:1450 [inline]
 exc_page_fault+0x94/0x2a0 arch/x86/mm/fault.c:1506
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:580

read to 0xffff88810252302c of 4 bytes by task 17339 on cpu 0:
 mm_update_next_owner+0x1d9/0x4e0 kernel/exit.c:388
 exit_mm+0x337/0x430 kernel/exit.c:500
 do_exit+0x41f/0x1690 kernel/exit.c:812
 do_group_exit+0x17d/0x180 kernel/exit.c:922
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:933
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:931
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:931
 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: 17339 Comm: syz-executor.1 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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