syzbot

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BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff888104a1fbd8 of 8 bytes by task 6197 on cpu 0:
 fasync_remove_entry+0xcc/0x120 fs/fcntl.c:1005
 fasync_helper+0x97/0xc0 fs/fcntl.c:1104
 pipe_fasync+0xce/0x150 fs/pipe.c:756
 __fput+0x5e3/0x650 fs/file_table.c:465
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104a1fbd8 of 8 bytes by task 6192 on cpu 1:
 kill_fasync+0x22/0x170 fs/fcntl.c:1146
 anon_pipe_read+0x6a2/0x750 fs/pipe.c:402
 do_iter_readv_writev+0x499/0x540 fs/read_write.c:-1
 vfs_readv+0x1ea/0x690 fs/read_write.c:1018
 do_readv+0xe7/0x210 fs/read_write.c:1080
 __do_sys_readv fs/read_write.c:1165 [inline]
 __se_sys_readv fs/read_write.c:1162 [inline]
 __x64_sys_readv+0x45/0x50 fs/read_write.c:1162
 x64_sys_call+0x29f8/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:20
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811a325270 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6192 Comm: syz.4.901 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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