[moderation] [v9fs?] KCSAN: data-race in p9_poll_workfn / p9_write_work (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0450d2083be6 Merge tag '6.10-rc-smb-fix' of git://git.samb..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13c0197c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=9cea9d6e22e152b5
dashboard link: https://syzkaller.appspot.com/bug?extid=b5b4f96f34012706c09e
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 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/04c015715988/disk-0450d208.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/93f908c0c5bd/vmlinux-0450d208.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ead896346b5c/bzImage-0450d208.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b5b4f9...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in p9_poll_workfn / p9_write_work

write to 0xffff88811621a89c of 4 bytes by task 3196 on cpu 1:
p9_write_work+0x42c/0x750 net/9p/trans_fd.c:498
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
worker_thread+0x526/0x730 kernel/workqueue.c:3393
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff88811621a89c of 4 bytes by task 23995 on cpu 0:
p9_poll_mux net/9p/trans_fd.c:646 [inline]
p9_poll_workfn+0x2bf/0x420 net/9p/trans_fd.c:1177
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
worker_thread+0x526/0x730 kernel/workqueue.c:3393
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000009 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23995 Comm: kworker/0:5 Not tainted 6.9.0-syzkaller-08995-g0450d2083be6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: events p9_poll_workfn
==================================================================


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