syzbot

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BUG: KCSAN: data-race in p9_conn_cancel / p9_poll_workfn

write to 0xffff888147602828 of 4 bytes by task 21669 on cpu 0:
 p9_conn_cancel+0x89/0x400 net/9p/trans_fd.c:200
 p9_write_work+0x3ac/0x740 net/9p/trans_fd.c:523
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read to 0xffff888147602828 of 4 bytes by task 21676 on cpu 1:
 p9_poll_mux net/9p/trans_fd.c:626 [inline]
 p9_poll_workfn+0xc0/0x410 net/9p/trans_fd.c:1167
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x00000000 -> 0xffffffea

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21676 Comm: kworker/1:11 Not tainted 6.6.0-rc2-syzkaller-00027-g5d2f53532ecc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Workqueue: events p9_poll_workfn
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