syzbot

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BUG: KCSAN: data-race in pipe_poll / pipe_resize_ring

write to 0xffff88811b1c8418 of 4 bytes by task 3994 on cpu 0:
 pipe_resize_ring+0x2c3/0x350 fs/pipe.c:1347
 pipe_set_size fs/pipe.c:1398 [inline]
 pipe_fcntl+0x2e3/0x350 fs/pipe.c:1439
 do_fcntl+0x667/0xdf0 fs/fcntl.c:543
 __do_sys_fcntl fs/fcntl.c:591 [inline]
 __se_sys_fcntl+0xb1/0x120 fs/fcntl.c:576
 __x64_sys_fcntl+0x43/0x50 fs/fcntl.c:576
 x64_sys_call+0x29a0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:73
 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

read to 0xffff88811b1c8418 of 4 bytes by task 27866 on cpu 1:
 pipe_poll+0x1ea/0x250 fs/pipe.c:694
 vfs_poll include/linux/poll.h:82 [inline]
 p9_fd_poll net/9p/trans_fd.c:240 [inline]
 p9_read_work+0x715/0x8a0 net/9p/trans_fd.c:398
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000010 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27866 Comm: kworker/1:8 Not tainted 6.17.0-rc1-syzkaller-00199-gdfd4b508c8c6 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events p9_read_work
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