[moderation] [v9fs?] KCSAN: data-race in p9_conn_cancel / p9_poll_workfn (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d025e2092e2 Merge tag 'erofs-for-6.9-rc2-fixes' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13141231180000
kernel config: https://syzkaller.appspot.com/x/.config?x=aa27611f143168c9
dashboard link: https://syzkaller.appspot.com/bug?extid=a789bed6117496300826
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [asma...@codewreck.org eri...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@crudebyte.com lu...@ionkov.net v9...@lists.linux.dev]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/25a7994bce97/disk-8d025e20.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd186f3a786f/vmlinux-8d025e20.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a958ca120141/bzImage-8d025e20.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a789be...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in p9_conn_cancel / p9_poll_workfn

write to 0xffff88813c87ec28 of 4 bytes by task 10042 on cpu 1:
p9_conn_cancel+0x89/0x400 net/9p/trans_fd.c:200
p9_read_work+0x771/0x8d0 net/9p/trans_fd.c:407
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
worker_thread+0x526/0x730 kernel/workqueue.c:3416
kthread+0x1d1/0x210 kernel/kthread.c:388
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

read to 0xffff88813c87ec28 of 4 bytes by task 3171 on cpu 0:
p9_poll_mux net/9p/trans_fd.c:626 [inline]
p9_poll_workfn+0xc0/0x420 net/9p/trans_fd.c:1178
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
worker_thread+0x526/0x730 kernel/workqueue.c:3416
kthread+0x1d1/0x210 kernel/kthread.c:388
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

value changed: 0x00000000 -> 0xfffffffb

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3171 Comm: kworker/0:4 Not tainted 6.9.0-rc1-syzkaller-00061-g8d025e2092e2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: events p9_poll_workfn
==================================================================


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