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BUG: KCSAN: data-race in p9_conn_cancel / p9_fd_request

write to 0xffff888136659428 of 4 bytes by task 4048 on cpu 0:
 p9_conn_cancel+0x89/0x440 net/9p/trans_fd.c:200
 p9_poll_mux net/9p/trans_fd.c:632 [inline]
 p9_poll_workfn+0x15c/0x420 net/9p/trans_fd.c:1167
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

read to 0xffff888136659428 of 4 bytes by task 30956 on cpu 1:
 p9_fd_request+0x2c/0x2b0 net/9p/trans_fd.c:674
 p9_client_rpc+0x1c4/0x6e0 net/9p/client.c:697
 p9_client_version+0xa4/0x310
 p9_client_create+0x61b/0x7a0 net/9p/client.c:1026
 v9fs_session_init+0x100/0xcf0 fs/9p/v9fs.c:407
 v9fs_mount+0x78/0x660 fs/9p/vfs_super.c:125
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x49/0x190 fs/super.c:1489
 do_new_mount+0x200/0x650 fs/namespace.c:3145
 path_mount+0x4aa/0xb70 fs/namespace.c:3475
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3674
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0xffffff98

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30956 Comm: syz-executor.5 Tainted: G        W          6.2.0-rc2-syzkaller-00282-g0a71553536d2-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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