syzbot

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BUG: KCSAN: data-race in do_coredump / mm_update_next_owner

write to 0xffff888090734024 of 4 bytes by task 18956 on cpu 0:
 freezer_do_not_count include/linux/freezer.h:109 [inline]
 coredump_wait fs/coredump.c:456 [inline]
 do_coredump+0x736/0x1fb6 fs/coredump.c:617
 get_signal+0xa7e/0x1290 kernel/signal.c:2728
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x190/0x1c0 arch/x86/entry/common.c:195
 swapgs_restore_regs_and_return_to_usermode+0x0/0x40

read to 0xffff888090734024 of 4 bytes by task 19082 on cpu 1:
 mm_update_next_owner+0x376/0x5a0 kernel/exit.c:389
 exit_mm kernel/exit.c:484 [inline]
 do_exit+0x638/0x1880 kernel/exit.c:788
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 __do_sys_exit_group kernel/exit.c:910 [inline]
 __se_sys_exit_group kernel/exit.c:908 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:908
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19082 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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