syzbot

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BUG: KCSAN: data-race in __fput / setattr_copy

write to 0xffff88811d4f14d8 of 2 bytes by task 13364 on cpu 0:
 setattr_copy+0x199/0x4a0 fs/attr.c:344
 shmem_setattr+0x5be/0x7c0 mm/shmem.c:1357
 notify_change+0x872/0x8f0 fs/attr.c:546
 chmod_common+0x141/0x270 fs/open.c:647
 do_fchmodat+0xa4/0x150 fs/open.c:694
 __do_sys_chmod fs/open.c:718 [inline]
 __se_sys_chmod fs/open.c:716 [inline]
 __x64_sys_chmod+0x38/0x50 fs/open.c:716
 x64_sys_call+0x2aaf/0x3000 arch/x86/include/generated/asm/syscalls_64.h:91
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811d4f14d8 of 2 bytes by task 13396 on cpu 1:
 __fput+0x2b9/0x650 fs/file_table.c:469
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0x1f7/0x6f0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x1d3/0x2a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x41c0 -> 0x435e

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13396 Comm: syz.4.2293 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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